As someone who often wonders about the quality of the air we're breathing in – primarily down to the fact we live on a busy high street – when I was offered the chance to test the Aranet4 HOME monitor, I was more than happy to give it a try.

While I have a carbon monoxide detector, and use an air purifier in the main living space, I was interested to just how clean my air was, how humidity was affecting my home, and if there were any problems in particular rooms.

Everywhere is single-glazed and the only means of ventilation are opening the windows – which at the front of the property open onto the street – and extractor fans in bathrooms. I dry my washing indoors, and am a frequent dehumidifier user, so it's no surprise I've been wondering what the air in my home is really like.

Buy the Aranet4 HOME monitor today

How the Aranet4 HOME monitor works

The Aranet4 HOME is a small, screen-based indoor air quality monitor that tracks CO₂ temperature, humidity and air pressure in real time.

It provides lab-grade CO₂ measurements using a NDIR (non-dispersive infrared) sensor, and the CO₂ levels are measured in parts per million (ppm). CO2 levels are commonly used as an indicator of ventilation effectiveness, with rising levels generally suggesting insufficient air exchange – or in other words, stale air being present.

While it's impossible for no C02 to be present given it's in the air we breathe out, good home ventilation naturally keeps air flowing, and therefore reduces the amount of CO2 that is present.

According to the makers of the Aranet4 HOME monitor, a well ventilated indoors should register around 400 – 800 ppm. 800 – 1200 ppm indicates moderately raised levels, while anything above 1200ppm would suggest poor and insufficient ventilation.

The reasons levels matter is because breathing poor quality air can have a number of implications. As well as reducing your cognitive abilities (particularly concerning if you have a home office, or a multi-generational household), higher levels can also increase the risk of airborne infections circulating.

In addition to the CO2 readings, temperature readings are taken so you can check if your home is at the recommended levels throughout the year, particularly helpful in winter when the minimum house temperature should be 18°C to help prevent mould and damp.

Humidity levels are taken as this is usually a key concern for homeowners due to high humidity again being associated with related moisture build-up problems. And, the one reading that I didn't realise also contributed so much to your home's health is the atmospheric pressure number.

Imbalances in pressure can impact a number of conditions in your home. In the winter, negative pressure – when the levels inside are lower compared to outside – can lead to cold air and pollutants being drawn inside. This can impact energy bills and could change your air quality.

Positive pressure – when it's higher inside than out – can then push dry air out and pull warm, moist air inside, pushing it into your home or even into cavity walls rising interstitial condensation.

How to read the results

In terms of how you read the results, while the on-screen display is clear and simple to read, the monitor also connects with the Aranet app via bluetooth and also lets you pull up graphs to compare the results over time.

The front of the monitor – or the app screen shows all four readings on a constant basis, and they are updated to a time setting of your choice. Mine updates every 5 minutes.

Subscription free, it's designed to give you clear indicators when air quality drops and ventilation is needed. This is achieved in two ways. Firstly the bar on the monitor display moves between the red, yellow and green strips to show where your CO2 levels sit, but you can also activate a buzzer which will alarm if your levels exceed 1400 ppm. This can also be adjusted to a lower amount via the app.

The constant humidity display is particularly handy during the winter months when you might be wondering if you need to partake in some house burping in order to prevent condensation and mould building up in your home. Or, if like me, you have more moisture than normal due to drying clothes indoors.

And, if you don't have a smart thermostat installed, the temperature function will identify if your house is getting too hot or too cold, potentially helping you to be more energy-efficient as a result.

Atmospheric pressure, is also clear and can again be seen in an easy-to-read graph, which, like the other figures, can be set to show daily, weekly or custom date readings.

Setting up the Aranet4 HOME monitor

The Aranet4 HOME arrived in small box, and at first glance was pretty unassuming. It looked more industrial in appearance than I was expecting, but given its compact size – 70 x 70 x 24mm and only 104g in weight – it's discreet enough that you wouldn't really notice if it was on display. Plus, as it can also be wall-mounted, it could also be located somewhere that wasn't in full view.

Once opened, a guide is inside with a QR code that when scanned leads you to the set-up instructions. All that you physically need to do is remove the stickers on the front of the monitor and add batteries to the rear. These are provided, but even replacing them when they run out won't be expensive as they are standard AA batteries. I don't know about you, but I always have some floating around in my kitchen drawers, and often stock up on bulk packs such as this pack of 40 AA Amazon Basic alkaline batteries as my sons always seem to need them for gaming controllers.

Once the batteries were in, I scanned the QR code which led me to this clear, simple guidance regarding the next steps. It was an easily scrollable PDF on mobile (also available via the website) which explained what the display showed, how to configure settings on the monitor if you didn't want to connect via the app, or how to get the app to connect your monitor using bluetooth.

Set-up, including pairing to the app took around 6 minutes in total, which meant that from unboxing to getting real-time results took less than 10 minutes. Not bad for a piece of kit that could be boosting the well-being of my family, and the health of my home.

How I've tested the Aranet4 HOME monitor

One of the things I've liked the most about testing the Aranet4 HOME monitor is just how easy it is to move it around my home. I've used it in my bedroom, my ensuite bathroom, my son's bedroom and the main open plan kitchen, dining and living room area in order to see how each room differs from the other.

In each room, I've placed it on a shelf or unit where I can easily see it, but it's the app I've checked the most when I want to see just what's going on with the air. And, while I'm only monitoring the results of one Aranet4 HOME monitor, you can add more to your network, name them using the room where they are located, and then toggle through each different set of readings. Something that could be handy in a larger home, or if you want to keep an eye on your basement ventilation for example.

What results have I seen to date?

The temperature in my home is less of a concern for me as despite the single glazing, using the window shutter tip that's helped me stay warm in winter and cooler in summer means we're never really cold. I've set my Hive smart thermostat to manage heat output through the day, and using the Dreo Smart Whole Room Heater tops up a room if I don't need to boost all of the radiators. Then, last summer, when it got particularly hot, the Meaco Fan 10" Sefte Pedestal Air Circulator helped keep me cool.

So, when reviewing the Aranet4 HOME monitor, I've been more interested in the CO2 levels and humidity, although the atmospheric pressure reading shows imbalances that I need to keep an eye on as well. Ideally as it should match the outdoor level, the line needs to be more consistent than it currently is.

1. CO2 levels and readings

While the buzzer has never gone off on the Aranet4 HOME monitor to indicate the CO2 levels are above 1400ppm in a room, it has crept into the mid, and even high range more times than I thought it would.

I've only noticed this on the monitor screen once as I don't spend my whole day looking at it. But, the appeal of this monitor for me is the fact it I can check everything on an app when I want to.

While I've not spotted any obvious patterns yet in terms of why the CO2 rises sometimes, I suspect over time I may as I continue to trial it around my home. As I've only got one monitor, I have had to note the times and dates when it is moved into a different room to try and establish where the problem may be, but for the purposes of reviewing the product that's fine. If I was considering them on a permanent basis, more monitors named to each room would certainly be a more sensible solution.

As we're moving into the warmer weather with windows being opened more frequently, I would hope to see less yellow and more green readings on the graph results but only time will tell.

2. Humidity levels

Overall, given the weather continues to be changeable and I continue to dry washing indoors as I have no outdoor space, I'm pleased with the humidity levels in the property. Most experts say that normal humidity levels in a house should be in the 40-60% range and so far, the monitor has only registered one day when it exceeded those numbers.

While I already use the DeLonghi DEX212F 12L Tasciugo AriaDry Dehumidifer to help dry laundry, I also have the MeacoDry ABC 12L dehumidifier in my bedroom and it's made me question whether I should maybe still be using this a little more to prevent any condensation until the warmer weather has fully arrived as it's only in bedrooms we are still noticing the odd appearance of window condensation.

As I have sash windows, I don't have trickle vents that could help with some natural air flow to avoid this. So for now, it's back to some house burping and a few more dehumidifier sessions to keep the air cool and fresh.

Final verdict

So, has the Aranet4 HOME monitor made me feel more comfortable about the air in my home? Overall, the answer would certainly be yes. It's raised a few questions regarding CO2 levels, but given I live in an older, listed property on a high street I'm not surprised that the air isn't as clean and fresh as it could be in a new home, where building regulation rules around ventilation would alleviate these issues.

The humidity readings have reassured me that I'm managing this fairly effectively, but that there's always room for improvement. It's easy to assume that once winter is over you don't need to worry, but I think I do need to pay more attention while the weather is still so unpredictable. And, as mentioned, the atmospheric pressure has made me realise just how much there is to keep an eye on with home air quality.

In terms of the negatives, I'd say the first is that the appearance of the monitor is less appealing than it could be for a product that's meant for a home. What's perhaps more frustrating is that there is a solution in the form of a sticker set that can be applied to the front of the monitor. They have space so that the display is clear, but cover the internal workings. But, the problem is they aren't yet available in the UK.

And then of course there's the price. It's not cheap, and a quick internet search pulls up considerably lower priced alternatives such as this Air Quality Monitor from Amazon that appears to do much the same job. That said, without investigating it or testing it, it's impossible to compare.

However, the Aranet4 HOME monitor has been developed alongside a range of professional products designed for the workplace and far bigger settings than a home. It's this expertise that has been used on the home products that make me more confident it's reading the air to a higher standard than other options. Plus, with a range of additional sensors available, it would be easy to create a whole home system to give you total control over your home.

If I'd invested in a hefty home renovation of an older property, adding these throughout the home would probably be an investment I'd consider. Monitoring the results could help give advance warning if there were problems with excess moisture from damp for example. If a building survey had noted radon below ground, you could also add a radon monitor to check if levels were problematic.

Would I buy one for a brand new home? It's unlikely unless I started to have concerns that the levels of ventilation weren't up to standard, but, it's good to know that high-level monitoring is available for a residential setting if needed.

And, if I was to buy them, I'd certainly want stickers to make them look that little bit more aesthetic.

Green mould is a familiar issue in many UK homes, especially during colder months when condensation levels rise. It often appears in corners, around windows, or tucked behind furniture, and while it may not seem as serious as dreaded black mould, it’s still a clear sign that excess damp is present. Although it isn’t usually dangerous, prolonged exposure can irritate airways and trigger symptoms for those with asthma or allergies.

Like other types of mould, green mould forms when warm, moisture-laden air meets cold surfaces. Poor ventilation, uneven heating, and gaps in insulation can all create the right conditions for spores to settle and grow.

Thankfully, green mould is usually a symptom rather than a structural problem. In this guide, we’ll show you how to identify the source of excess moisture, remove the mould safely and effectively, and put the right preventative measures in place – so it stays gone.

What is green mould and how can you identify it?

Green mould isn’t one single species but a broad term for several fungi that appear green due to the colour of their spores. As Jess Thomas, director of Drainage Central, explains: “Green mould is a type of fungus, but it is not one particular type of mould. Usually, green mould is Aspergillus, Penicillium or Cladosporium."

"It occurs in places where there are high levels of moisture and organic matter, such as bathrooms, kitchens, windowsills, walls and even food," says Jess. "Unlike black mould, which is associated with water damage, green mould can grow in a wider range of places and is fuzzy or powdery instead of slimy and wet.”

However, according to Michael Zohouri, founder of Pyramid Eco, "the colour is less important than the cause. Whether it looks green, black or even slightly pink in some cases, mould is always a sign of excess moisture. Greener variations tend to show up more clearly on walls and fabrics, which is why people notice it."

What causes green mould on internal walls?

When it comes to green mould on walls, moisture / damp is almost always at the root of the problem. In the UK, our cooler temperatures and frequent rainfall make condensation a common culprit, particularly during autumn and winter.

Mark Irving, expert at Build & Plumb, explains that a build-up of excess moisture inside the home creates the ideal conditions for mould spores to settle and spread. "From everyday activities such as cooking and showering to hidden leaks and insulation gaps, there are several reasons why green patches might start appearing on your walls":

• Condensation from cooking, showering and drying clothes indoors.
• Poor ventilation, including ineffective extractor fans and closed trickle vents.
• Rising damp, often linked to a failed damp-proof course.
• Penetrating damp, caused by damaged guttering, leaking pipes or faulty pointing.
• Poor heating and insulation, particularly where cold spots allow moisture to settle on surfaces.

Condensation or damp problem – how can you tell?

It’s crucial to establish whether green mould is being caused by everyday condensation or a more serious structural damp issue, as the best way to treat and remove the mould will depend entirely on the underlying source.

According to Mark Irving, mould caused by everyday condensation tends to form in predictable places, such as corners of rooms, around window reveals or behind furniture positioned against external walls. It's often worse during the colder months, when warm indoor air meets cooler surfaces and moisture settles.

More serious damp issues, however, usually leave additional clues. Penetrating damp may show itself through blistered paint, damaged plaster or staining that corresponds with external defects such as faulty guttering or cracked pointing. Rising damp often creates tide marks along the lower portion of walls, accompanied by peeling wallpaper or deteriorating skirting boards.

Mould linked to structural moisture problems is typically more persistent, forming in larger patches and often accompanied by visible water marks or ongoing damp patches. If mould returns quickly after cleaning – even after steps have been taken to improve air quality and airflow – it may indicate that the issue runs deeper than simple condensation and warrants further investigation.

Is green mould dangerous?

“Whilst not all mould exposure can lead to illnesses, indoor growth should still be considered a potential health concern," cautions Mark Irving. "As mould reproduces, if inhaled, the spores can irritate the respiratory system. Even short-term exposure can cause symptoms such as coughing and wheezing. Those with recurring health issues, such as asthma sufferers or those with weakened immune systems, will be particularly vulnerable.”

Green mould isn’t typically toxic in itself, but that doesn’t mean it should be ignored. Over time, living with it and sleeping in the same room can increase exposure to airborne spores and potentially aggravate respiratory issues.

How to get rid of green mould on walls

The fast DIY method of removing green mould

Small areas of green mould (under 1m²) can often be treated on a DIY basis. Here's how the experts recommend cleaning it on your own:

• Ventilate the room by opening windows and close internal doors to limit spread.
• Wear gloves and a mask.
• Lightly mist the area with a specialist mould spray or a solution of white vinegar and water, and leave to sit for the specified amount of time before wiping.
• Use a damp cloth and avoid aggressive scrubbing.
• Dispose of cloths in a sealed bag.

A word of warning: “Wiping or disturbing mould can release spores into the air, especially if you disturb the mould when it is dry,” warns Jess Thomas “You should never dry scrub or dry brush mould. When cleaning mould, ensure that you are wearing the proper protective equipment such as a mask, goggles and gloves.”

Shop mould removal products

Longer term solutions

“The long-term solution is always moisture control,” says Michael Zohouri. “Mould is just the symptom. The real issue is that something in the house is staying damp for too long.”

He advises tackling leaks as a priority. “The first thing is to deal with any leaks straight away. Even a small drip under a sink or a slow pipe leak inside a wall can create the right conditions for mould to keep returning.

Ventilation, he adds, is just as important. “Use your extractor fans every single time you shower or cook, and make sure they are actually venting outside rather than into a loft space.”

Maintaining a steady ambient temperature through the colder months can also make a big difference. “When walls get very cold, condensation forms much more easily.”

Finally, he points to a common but often overlooked issue: furniture placement. “Something I see all the time is furniture pushed tight against external walls. Leaving a small gap behind wardrobes and sofas allows air to circulate. That can stop mould forming quietly out of sight.”

FAQs

Will green mould go away on its own?

Sadly, no. Mould won’t simply disappear once it’s made itself at home. While a spell of drier weather or improved heating might make it look less obvious, the spores remain and if moisture levels rise again, it will quickly return. The only way to get rid of it properly is to tackle both the visible growth and the source of the damp that’s feeding it.

Where is green mould most likely to appear?

"Bathrooms and kitchens are obvious mould hotspots because of steam," says Michael Zohouri, founder of Pyramid Eco. "Basements are also common, especially if they are cool and slightly damp."

"Mould on window frames is another frequent location, as warm indoor air hits the cold glass and surrounding plaster, and condensation forms. Over time, mould can grow on seals and paintwork," Michael adds.

But bedrooms are actually one of the biggest problem areas. "People keep doors and windows closed overnight, and breathing alone releases moisture. If that room has a cold external wall and limited airflow, mould can form quite quickly."

Is it safe to sleep in a room with green mould?

“Although you can technically sleep in a room where green mould is present, it is not recommended due to the health risks associated with prolonged exposure to mould,” warns Jess Thomas.

Bedrooms are spaces where we spend hours at a time, often with doors and windows closed. Repeated exposure to airborne spores – particularly overnight – can aggravate asthma and other respiratory conditions. If mould is visible in a bedroom, it’s best dealt with promptly.

Can you paint over green mould?

Painting over mould might seem like a quick fix, but it rarely solves the problem. If the underlying moisture hasn’t been addressed, the mould will simply grow back through the new paint. Before redecorating, the area should be thoroughly cleaned and fully dried, and any ventilation or damp issues resolved. Anti-mould paint can help in high-moisture areas such as bathrooms, but they’re a preventative measure, not a cure.

When should you call for professional help?

If green mould keeps staging a comeback – or has spread beyond a small, manageable patch – it may be time to call in the professionals. A qualified surveyor or damp specialist can dig a little deeper to uncover what’s really going on, whether that’s a hidden leak, insulation gap or persistent condensation issue. Simply scrubbing away what you can see might tidy things up for now, but unless the moisture source is tackled, it’s likely to be a short-lived victory.

How can you tell if it's green mould or mildew?

Telling green mould vs mildew apart can be tricky, as both thrive in damp conditions. Mildew is usually lighter in colour – white, grey or pale yellow – and tends to sit on the surface, making it easier to wipe away. Green mould is typically darker, often green-grey or almost black indoors, and can look fuzzy or velvety, spreading more quickly if moisture persists. Outside, green growth on walls is often algae rather than mould, appearing brighter and more slimy due to rain and shade rather than indoor humidity.

If you suspect excess moisture is behind green mould on your walls, it could be worth investing in one of the best dehumidifiers and brushing up on how to test for mould and how to treat damp properly to prevent it returning.

Bathrooms are one room in the house that really need to offer a consistently comfortable environment – after all, you are likely to spend much of your time in this space in a state of partial or total undress. Not the place for sub-zero temperatures.

You might think you are doing all the right things – installing one of the best bathroom extractor fans, fitting correctly sized heated towel rails and radiators or even an underfloor heating system – yet if you are still finding yourself shivering when you step out of the shower, something is not right.

It might surprise you to learn that your extractor fan could be the culprit here – we spoke to the experts to explain why this might be and how to put a stop to this icy issue once and for all.

Can bathroom extractor fans make a room feel colder?

Many people have never considered that their extractor fan might be interfering with their bathroom heating, causing their room to feel chilly yet, according to the experts, this is a far more common problem than you might think.

"Extractor fans play an important role in controlling moisture, but if they're not correctly specified or set up then they can make a much bigger impact on heat loss than homeowners may realise," explains Ryan Marshall, director of Marshall Clean Heat and Power. "Bathrooms are usually small, highly heated spaces, so even a modest extraction rate can replace warm air with cold air very quickly – especially in colder months."

Martyn Fowler, founder of Elite Renewables, elaborates. "The fan changes how air behaves in a controlled space. When an extractor fan runs, it creates negative pressure in the bathroom. That means air has to come from somewhere to replace what’s being pulled out.

"If the door is open, it might pull warm air from the rest of the house," continues Martyn. "If the door is closed and the room is sealed, it can draw in colder air through gaps in the building envelope, such as trickle vents or even the fan duct itself if there’s no backdraught damper."

There are actually several reasons why bathroom extractor fans might end up causing more problems than they solve – we're here to reveal them.

1. Fans that are left to run for too long

Bathrooms can become steamy places meaning the temptation can be to leave your extractor fan running at full blast long after it has been used in order to dispose of all that damp, hot, muggy air – but this could be a big mistake.

"One of the most common issues we see is fans running for longer than necessary," reveals Ryan Marshall. "Long overrun times or continuous-run models can remove more warm air than your heating system can comfortably replace, which leaves the room feeling noticeably colder."

"The most common issue is fans that run constantly or stay on far longer than they need to," agrees Michael Zohouri, founder of Pyramid Eco. "If the fan keeps pulling air out after the moisture has cleared, you’re just removing warm air and replacing it with cold from other parts of the house."

The solution: "Start by checking how the fan is controlled," says Michael. "If it’s wired to the light switch, think about upgrading to a humidity-sensing model. These only run when moisture levels are high and switch off when things are dry again. So you don’t lose any heat just because someone forgot to turn it off."

2. Faulty or missing backdraught damper

All extractor fans used for bathroom ventilation should be fitted with a backdraught shutter, a valve that opens when the fan is running to let stale air out but that should then automatically close when the fan is not in use.

"It’s really important that the fan has a proper backdraught shutter that seals fully when the fan is off," explains Martyn Fowler. "Without that, the duct can act as a pathway for cold air to move back into the bathroom."

"If the fan hasn’t got a working backdraught damper, or if the ducting around it isn’t sealed properly, cold air can come back in from outside," adds Michael Zohouri. "Sometimes you’ll actually feel the chill coming straight through the fan."

The solution: Take a look and check that the backdraught flap is working and sealing properly when the fan is off.

"Insulated ductwork and a good-quality non‑return valve will make a big difference by preventing cold air being pulled or blown back into the bathroom when the fan isn’t operating," says Ryan Marshall.

3. Choosing a fan that's too powerful

Choosing an extractor fan that is not specified correctly for the size of you bathroom can cause all kinds of problems, heat loss included – if it is not powerful enough it won't pull the stale air and steam out properly, but if it is too powerful you could find yourself wasting both heat and energy.

"One of the most common issues is excessive air extraction – if a fan is too powerful for the room size, it can pull warm air out faster than it’s replaced, creating a noticeable chill," explains Ruth MacEachern, product manager at ventilation specialists EnviroVent.

"Bigger isn’t always better," agrees Michael Zohouri. "If the fan is rated for a much larger room it will pull out too much air too quickly and take the heat along with the steam."

The solution: Choose an extractor fan with the correct extraction rate for your bathroom's size. Calculate its volume by multiplying it length by its width by its height (L x W x H). It is advisable to have at least four air changes per hour so you would then multiply the figure you got by four. This would give you the required extraction rate of your fan in m³/h.

Shop our favourite bathroom extractor fans

4. Bad extractor fan positioning

It is no good just sticking your extractor fan in any old position within your bathroom layout – while you might not want it ruining your bathroom design ideas, you really need to give some thought to its location if you don't want it to be the cause of post-bath shivering.

"Layout matters," states Martyn Fowler. "If the extractor is positioned directly above the shower or bath and runs for long periods, it can strip warm air very quickly and cause a noticeable drop in temperature."

The solution: "In compact bathrooms, drawing air from a higher corner or slightly away from the shower can still remove moisture effectively, but in a more controlled way," advises Martyn.

5. Speed settings are being overlooked

Running your extractor fan flat out in a quest to beat mould in the bathroom is not the best method of getting the most out of it – just another way in which it could make your bathroom feel cold.

"Fan speed plays a key role," says Martyn Fowler. "Many newer models offer variable speed settings, which makes a big difference in smaller bathrooms. Instead of running flat out all the time, the fan can operate at a lower rate for background ventilation and only ramp up when steam levels rise. That reduces how much warm air is removed and helps keep the room temperature more stable."

The solution: Choose an extractor fan with variable speeds and that responds to the moisture levels in your space.

"A humidity-controlled fan works on demand," explains Martyn Fowler. "It switches on when moisture levels rise, and switches off once the air has dried out. That means you’re removing steam when it’s needed, but you’re not continuously pulling warm air out of the room once the job is done."

6. Uninsulated fan ducting

It is crucial, if you want to maintain a comfortable temperature in your bathroom, that you check the way your extractor fan is ducted to outside. It is also really important to ensure that the ducting you use is insulated.

"Poorly sealed ducting or gaps around the fan housing can allow cold air to enter from outside," explains Ruth MacEachern.

The solution: "Make sure your ducting runs properly to an outside wall or roof vent, and that it’s insulated if it goes through a cold loft," advises Michael Zohouri. "That stops condensation forming in the duct and helps prevent cold air from being pulled in."

7. Drawing fresh air from a cold spot

Along with checking that ducting seals are intact and that insulation has been considered, do think about how the source of your fresh air could be affecting bathroom temperatures.

"When a fan pulls humid air out, it has to be replaced from somewhere else in the property," picks up Ryan Marshall. "If that 'make-up' air is being drawn from unheated areas, such as hallways, loft voids or through draught points, the temperature drop can be significant, especially in older or less airtight homes."

The solution: Along with making sure your fresh air is not coming from an unheated area, and addressing draught proofing throughout your home, Michael Zohouri has another solution.

"Keep the door closed when the fan is running," he says. "This allows the fan to draw air from under the door rather than from the rest of the house."

FAQs

Do bathrooms need extractor fans?

If you are renovating a bathroom that currently has no extractor fan, you may well be keen to avoid any extra disruption – but is an extractor fan a legal requirement?

The UK Building Regulations state that bathrooms must have some form of ventilation, although this can be provided in the form of either an extractor fan or an openable window. However, in the case of new builds, bathrooms are required to be fitted with mechanical ventilation (due to them being more airtight).

Even if you are not building a new house, it is still highly recommended to fit an extractor fan. Opening a window for prolonged periods in the depths of winter to deal with humid, stale air is impractical, plus mechanical ventilation is a great way to avoid issues with damp or mould arising.

If you have found damp in the bathroom you should not only address your ventilation methods, but also be on the lookout for leaks in pipework or behind tiles. If you can, opening windows for a few minutes every day will help too.

Finding mould in your loft can be pretty alarming, especially if this is a space you rely on to store precious belongings or items such as Christmas decorations or out of season clothing – things you really don't want to pull out and find covered in the stuff.

While there are plenty of mould removal tricks you can employ to deal with the issue in the short term, it is really important to discover the root of the problem if you want to ensure it doesn't become a recurring issue that could, eventually, lead to serious damage, not just to the items you keep up there, but also to the structure of your home.

The good news is that there are steps you can take to resolve mould in the loft and, with the help of some top experts in the field, we're here to to explain exactly what they are.

Why does mould appear in lofts?

It might be reassuring to know that mould in lofts is actually quite common, caused by a number of things, although there tends to be one main culprit: poor loft ventilation.

"In most cases, warm, humid air from the living areas below rises and enters the loft through gaps in the ceiling, around the light fittings or through poorly sealed hatches" explains HVAC and ventilation expert David Miloshev from Fantastic Services. "When that warm air meets the colder surfaces of the roof timbers or underlay, the moisture condenses, creating the perfect environment for mould spores to thrive.

"Insufficient ventilation is a key factor," continues David. "If the loft lacks adequate air movement from soffit, eaves or ridge vents, the moisture becomes trapped and remains in contact with those cold surfaces for long periods."

"Mould in lofts is nearly always caused by trapped moisture and poor ventilation," agrees Michael Zohouri, founder of Pyramid Eco. "Warm, moist air from bathrooms and kitchens rises into the loft. If there’s nowhere for that air to escape, it condenses on cold surfaces such as roof timbers and insulation. It's much more noticeable in the winter because the loft is cold and the temperature difference increases condensation. It creates the perfect environment for mould to grow."

Why do some homes suffer from mould in the loft more than others?

Not all homeowners experience the problem of mould in their loft. This is not just down to them having better home ventilation measures in place. In some cases, the way in which people live in their homes can exacerbate the problem.

"In some homes, the issue is made worse by bathroom extractor fans or tumble dryer vents discharging moist air directly into the loft instead of outside," reveals David Miloshev. "Poor insulation, or insulation that’s been pushed right up to the eaves can also restrict airflow and exacerbate the problem."

How can you prevent mould in the loft?

Thankfully there are preventative measures you can take to put a stop to mould forming in your loft.

"Preventing mould in loft spaces requires controlling the moisture levels and ensuring proper ventilation throughout the area," explains David Miloshev. "The first step is to stop warm, humid air from the living spaces below from entering the loft. This can be achieved by sealing any gaps around the light fittings, ceiling hatches and any service penetrations, and ensuring loft and roof insulation is correctly installed without blocking airflow from soffit or eaves vents.

"Ventilation itself is critical," continues David. "Soffit vents, ridge vents or additional roof vents should allow a continuous flow of air that carries moisture out of the loft. Any appliances that produce moisture, such as bathroom extractor fans or tumble dryers, should be correctly ducted to the outside instead of discharging into the loft.

"It’s also important to maintain a temperature in the loft that minimises condensation," adds David. "This can be supported by ensuring insulation is adequate but not obstructing airflow. Finally, regular inspections are also useful. Checking for blocked vents, signs of leaks or condensation buildup for early intervention before mould can establish itself."

What should you do if you find mould in your loft?

If you have noticed any mould in your loft, what should you first steps be?

"First you need to stop the source of moisture," says Michael Zohouri. "That might be a ventilation issue, a leaking roof tile, or an extractor fan that’s not vented properly. Once the area is dry and the airflow is working as it should, you can treat the mould."

"If you find mould in a loft, the first step is to identify and address the underlying cause instead of just removing the visible growth," picks up David Miloshev. "Start by inspecting the space for sources of moisture, such as roof leaks, blocked or inadequate ventilation or warm, humid air escaping from the rooms below. Once the source is identified, it should be corrected. Repair any leaks, unblock or install proper ventilation and make sure to look into how to insulate a loft correctly to allow airflow.

How do you remove mould in a loft?

Of course even once you have found the cause of your mould and put measures in place to prevent it from returning, you still need investigate how to remove mould from walls and the space in general once it has taken up residence.

"If the mould is only in a small area and caught early, you can clean it yourself," says Michael Zohouri. "White vinegar works well as a natural mould remover. Spray it directly onto the surface, leave it for an hour, then scrub with a cloth and wipe the area dry. There are also specialist mould treatments available from DIY shops if you prefer a ready-made solution. Always wear gloves and a mask while cleaning, and avoid dry brushing as that can release mould spores into the air."

"Large or persistent infestations will require professional remediation, particularly if the mould has penetrated the insulation or roof timbers," advises David Miloshev. "After cleaning, monitor the loft over time to make sure that moisture levels are controlled and the ventilation is functioning correctly. Failure to fix the source of the problem will almost always result in the mould returning."

Shop mould removal essentials

FAQs

Is mould in the loft dangerous?

Mould can pose a serious health risk if left untreated in a home, particularly if any of the residents suffer from skin or respiratory problems. But how about when it is up in the loft?

"Mould in lofts can be hazardous, although the level of risk depends on the type of mould, the extent of the infestation and the exposure of occupants," explains David Miloshev. "Many loft moulds release spores into the air, which can enter the living spaces through gaps or ventilation, potentially causing allergic reactions, respiratory irritation or exacerbating conditions such as asthma. Prolonged exposure to certain types of mould, particularly black mould, can be more serious and can lead to persistent respiratory issues, skin irritation or other health problems.

"The affected structural materials themselves are usually not immediately in danger, but mould can weaken timber over time if left untreated, especially if it’s combined with ongoing moisture issues," continues David. "The primary concern is controlling the moisture and preventing the spores from spreading into the home. Anyone cleaning mould should take precautions with protective equipment to minimise inhalation or contact."

If you have found mould in your loft you might be wondering where else in your home it might be lurking. Our guide on hidden mould hotspots is a must-read to ensure you're not missing anything.

Condensation can be a nuisance in the winter, and if left unchecked, it can develop into more serious problems, such as mould growth, property damage, and health issues.

While the best dehumidifiers are an obvious solution, many come with a hefty price tag, so it’s no surprise that people look for more affordable alternatives – or ones they already have in their cupboards – like a cooling fan, for example.

To find out whether this could work, or if it will simply spread the moisture around the window, I chatted with some air quality experts to hear their thoughts and tested it myself in my condensation-prone kitchen. Keep reading to find out what happened.

Can you get rid of condensation with a cooling fan?

Since my kitchen windows steam up almost every day in winter, I was eager to try this condensation hack after seeing it online. The next time I noticed the windows had misted up, I grabbed my trusty fan and placed it next to the glass – and, to my delight, the condensation quickly began to evaporate.

However, after speaking with Chris Michael, founder of Meaco, it seemed there was more going on than met the eye, and this wasn't a quick fix to my problem.

"A cooling fan won’t remove condensation," he explains. "You need a dehumidifier to extract moisture (water vapour) from the air."

It turns out that all a cooling fan will do is move the condensation around your window, rather than tackling the root cause of the issue (which is excess moisture in the air). If I wanted to stop window condensation from forming, using a dehumidifier or extractor fan would be a better solution.

In fact, if you live in a house with mould problems, you might make the situation worse – spreading the spores around your room. The best way to solve condensation is by ensuring your home has sufficient ventilation, controlling the humidity to a normal level, upgrading your insulation, and considering positive input ventilation.

The surface may appear to dry faster, but this doesn’t reduce the total moisture in the air. Instead, the moisture will simply redistribute elsewhere in the room, potentially settling on other surfaces and leaving you in the same situation you started with.

Laura Bradbury, Head of eCommerce at Vonhaus, adds, “Fans don’t remove moisture, but they can help reduce condensation when used alongside a dehumidifier or with proper ventilation. A fan with a strong airflow, such as a tower or pedestal fan, can help circulate air around windows and walls where condensation tends to build up. The goal is to keep the air moving and reduce cold spots where moisture collects.”

Michael tells me that there is one other thing a cooling fan could be handy with – and that's drying your laundry. "When used in conjunction with a dehumidifier, it can dry laundry in half the time without adding any real cost. This means that clothes can be dried in under two hours."

Our top dehumidifier picks

After testing this condensation hack on my windows, I hope it will save you from wasting time – or worse, making the problem bigger than it already is!

If you're struggling with condensation on your toilet cisterns, we've put together a helpful guide on how to deal with it and prevent it from happening in the first place. Or, if you're interested in finding the best extractor fans, our team of experts has rounded up their top picks.

Although you may know the answer to what are trickle vents, you may still wonder if that little flow of air really makes a difference to your home ventilation. Or, perhaps you feel it's a bit of an inconvenient eyesore that lets your heating flows out and an annoying draught come in.

But the reality is we do need them – albeit not in all homes – and in some cases there are potentially serious consequences if you don't have them.

So just what powers do these little strips of slatted plastic have, why doesn't every home in the UK need them and what happens if you should have them but you don't?

What are trickle vents?

In terms of their practical appearance, trickle vents are usually found at the top of your window or door frame.

“They are small openings built into window or door frames that allow a continuous flow of fresh air into a building, even when the windows are securely closed," explains Anthony Threlfall, head of marketing at Everest.

That said, while the most common version is found in the frame and has a plastic cover that can be opened or closed, there are in fact three types of trickle vents says Anthony:

• Through-frame or through-sash vents: The most common type, integrated directly into the window frame or sash
• Over-frame vents: Fitted above the window frame, often used when through-frame vents aren't possible
• Glazed-in vents: Positioned in the glazed area of the window, though this type may detract from aesthetics and is less commonly chosen

Why do we need trickle vents?

Anyone who's ever found a mould hotspot in their home, or become frustrated with a sweating toilet will understand the importance of home ventilation.

We generate a lot of moisture within our homes through daily routines such as cooking, washing, drying clothes and even breathing. This causes the humidity levels inside to rise. Once this humid air reaches a cold surface, it forms water droplets which turn into condensation.

If you don't deal with this problem, over time it can lead to more serious problems with mould and damp. But, with good home ventilation which extracts the air and replaces it with clean, fresh air from outside, the risk is reduced.

However, while good extraction and measures such as house burping can allow bursts of fresh air in, they are reliant on you remembering to do so, which is where the benefits of trickle vents start to reveal themself.

“Trickle vents help improve ventilation by allowing a “trickle” of air to circulate, preventing indoor air from becoming stagnant while reducing moisture build-up from the air that can cause mould," says Anthony Threlfall.

And while it's common to associate damp and mould with older properties, "they are just as important in modern houses which are designed to be more airtight,” confirms Anthony.

Trickle vents and building regulations

Of course, as well as their ability to improve air flow around the home, there's also bigger problem if you don't have trickle vents. They are part of the building regulations standards covering ventilation, meaning if you don't have them in your home, you could be breaking the rules.

“As of 15 June 2022, Building Regulations in England and Wales mandate that trickle ventilation must be fitted on all replacement windows and doors in habitable rooms," warns Anthony Threlfall.

"This includes bedrooms, living rooms, kitchens, and bathrooms - but excludes hallways and stairwells. Scotland already had similar requirements in place prior to this."

So, while trickle vents may only be providing background ventilation, it's considered an integral part of the rules when building a house. Although, as we'll cover next, not all homes are required to have them.

Do all homes need them?

Despite their obvious value, there are some situations when trickle vents may not be needed, and those where they should be installed – but they aren't.

“Certain scenarios may make trickle vents unnecessary or undesirable. Homes with mechanical heat recovery systems or continuous extract ventilation systems, for instance, typically do not require them to meet Building Regulations.

“On top of this, listed or historic buildings may be exempt from having trickle vents to preserve the property’s aesthetic. However, other forms of background ventilation would need to be provided to meet regulations," explains Anthony Threlfall.

Other scenarios when you may not spot trickle vents in place include:

• Older window installations: Windows and doors fitted before the 2022 regulation change may not include them
• Installer oversight or miscommunication: Some installers may not inform customers about the requirement - but, this is a legal requirement and can impact the sale of your property if you do not comply

Pros and cons of having trickle vents

When it comes to the pros and cons of having trickle vents, it's important not to underestimate just how powerful these little strips are. While they may only be a small cog in the big wheel of home ventilation, the consequences of poor air flow are big.

Issues with damp and mould may only seem like surface problems, but in fact run deeper. Untreated mould can lead to heath issues in the young, elderly and those with chronic conditions or respiratory problems.

Damp can lead to structural problems with roofs, walls and floors, and even though trickle vents may be small, that regular airflow will all contribute to a healthier and safer home.

Plus, one positive to trickle vents you may not have considered is how they can help with your home security costs, says Anthony Threlfall.

"Trickle vents allow for ventilation without compromising the security of your home. Some windows do have night latches, but these are not secure – they are an open window and would potentially not be accepted by insurance companies if you left your windows on the latch and were broken into."

Are there any downsides to having trickle vents?

That said, there are always two sides to every story and some of the potential downsides of trickle vents, according to Anthony Threlfall, could be considered as:

• Noise intrusion: It's worth noting that adding trickle vents to windows can impact any noise reduction measures you have on your windows. Since they create small openings, external noise can enter more easily
• Potential draughts: If left open during cold weather, trickle vents can create draughts in the room, but as mentioned, you can close them during the colder months
• Cleaning: The vents can accumulate dirt, so it’s important to keep them clean

Using trickle vents

“Although the vent itself can also be closed, they are designed to be left open all the time for continual ventilation, ensuring a gentle, uninterrupted flow of fresh air," advises Anthony Threlfall.

"This discreet, yet effective, ventilation helps expel moisture and airborne pollutants, preserving the purity and comfort of your home," he says, all while you carry on with your life.

"However, for optimal use, consider combining trickle vents with other forms of ventilation, such as the best extractor fans for bathrooms, and making sure your kitchen ventilation system is fully comprehensive," he advises.

FAQs

Should trickle vents be closed in winter?

“While trickle vents can technically be closed, it’s advisable to keep trickle vents open in winter to prevent damp and condensation," says Anthony Threlfall. "If you do close them due to cold draughts, ensure regular ventilation by opening windows for short intervals to maintain healthy air circulation.”

Do they affect the type of window covering you can have?

“Generally, trickle vents shouldn’t interfere with most window coverings like blinds or curtains. However, bulky or close-fitting fittings may partially obstruct the airflow and reduce their effectiveness," warns Anthony Threlfall.

"For instance, as they are typically located at the top of the window frame, coverings that sit flush against, or over this area, like certain roman blinds, perfect fit blinds, or full-height shutters, might restrict airflow if not positioned carefully.”

Do trickle vent stop condensation completely?

“Trickle vents help reduce the likelihood of condensation by allowing moist air to escape and fresh air to circulate. However, in homes with excessive moisture production (for example from cooking, showers, or drying clothes indoors), additional ventilation measures may be required to fully prevent condensation," advises Anthony Threlfall.

Are there any alternatives to trickle vents?

Alternatives to trickle vents include mechanical ventilation with heat recovery systems for continuous airflow while saving energy, continuous extraction systems, particularly in kitchens and bathrooms, and ventilation fans for more targeted airflow.

"However, while these systems provide effective ventilation, they are typically more expensive and require additional installation considerations compared to trickle vents,” says Anthony Threlfall.

You may also want to consider roof vent tiles, particularly if you are undertaking a loft conversion and want to avoid loft condensation or mould in your loft.

Can you retrofit trickle vents?

“Yes, trickle vents can be retrofitted into existing window frames," says Anthony Threlfall, "but the process can be complex. It involves drilling holes into the frame, which requires precision to avoid damaging the structure.

"At Everest, we recommend installing new windows with integrated trickle vents for optimal performance and a seamless finish," he says.

Good home ventilation also means getting the ambient temperature in your home right, but if you're keen to explore more ways of ventilating your home, make sure you have the right natural ventilation in place, and discover if you can potentially retrofit MVHR into an existing home.

EDITOR’S NOTE: An earlier version of this article included a quote from a purported expert whose credentials we have not been able to verify. The quote has been removed. We regret this lapse in our verification process and have updated our internal protocols to reduce the risk of recurrence.

While it's becoming more common for an MVHR (mechanical ventilation and heat recovery) system to be included in a new, self build project, the option to retrofit MVHR is less popular.

But, with an increasing focus on the need for our homes to be airtight and energy efficient, including an MVHR set up in your home renovation plans shouldn't be dismissed.

While it's not as easy as in a new build, it is feasible and can still reap rewards. Find out what's involved, how to get it right, and when you should consider other options instead.

Potential issues with an MVHR retrofit

"Retrofitting MVHR into an existing home can be technically challenging, but it is certainly achievable with the right planning and expertise," says Russell Smith, managing director and co-founder of Ecofurb.

"In older or occupied properties, space constraints, structural limitations, and the need for minimal disruption can complicate the process," he explains.

"Existing homes with solid timber joists, new steel beams and some vaulted ceiling can make finding the routes for the MVHR ducts very tricky," confirms David Hill, managing director of Carbon Legacy Ltd.

However, there are a number of different factors that can impact how easy the job of installing MVHR is.

"It largely depends on the property's layout, existing ventilation systems, and the level of airtightness. Homes undergoing significant renovation or whole house retrofits offer the best opportunity for MVHR integration, as ductwork can be concealed within floors, ceilings, or walls more easily," explains Russell.

"But, with tailored design, careful coordination, and skilled installation, MVHR can be successfully implemented, delivering improved indoor air quality and energy efficiency," he confirms.

How to make a retrofit easier

While installing MVHR in a new build means it can be fitted at the right time, without facing solid walls, existing ceilings or limited space, to retrofit MVHR requires more work upfront say the experts.

"There are several measures that can make MVHR installation in existing homes easier and more effective," confirms Russell Smith. "Early stage planning is always crucial as considering MVHR at the outset of any retrofit or home renovation project allows for better integration of duct routes and unit placement."

"The more extensive the renovation then the more likely you are of finding solutions to duct routes," adds David Hill. "It's also, worth noting, bungalows with existing lofts are perfect as all the duct work and the unit can go in the loft."

"Be prepared to have numerous discussions both before and during installation with the client, architect, engineer and other trades as well," says David. "Plus, installing ducts as early as possible in the renovation, and accepting that more ceilings or floors may have to come up to accommodate ducts and vents, will all ease the process.

"Also make sure you ask your installers to be as transparent and honest as possible, and make sure they talk you through each stage of an install, agree every duct route and compromise you will need to make to get the ducts and ceiling vents where they need to go," he adds.

"Engaging experienced designers and installers who understand the specific challenges of retrofit projects is key to ensuring a smooth and successful installation," agrees Russell.

As well as creating service voids from existing spaces, there are also a number of different techniques the experts employ when undertaking a retrofit MVHR scheme that can help disguise the install and avoid using up valuable space.

"Using compact or decentralised MVHR units in homes with limited space can also simplify installation, says Russell, "and additionally, improving the home's airtightness before or during the retrofit ensures the MVHR system operates efficiently.

"One common approach is to create service voids behind fitted furniture such as wardrobes, kitchen units, or bathroom cabinetry, allowing ductwork to be hidden without major structural work," he suggests.

"Boxing in ducts along the tops of walls or running them through existing bulkheads or chimney voids is another effective strategy. Flexible or semi rigid ducting can also be used in tight spaces where rigid ducts wouldn’t fit easily," he adds.

"In essence, smart design and a bit of creativity can go a long way in making MVHR retrofits both practical and unobtrusive," says Russell.

MVHR retrofit costs

The costs for an MVHR system in a new-build can vary depending on how sophisticated you want your system to me. Homes with MVHR that is in line with Passivhaus ventilation standards will naturally find themselves paying more than homeowners who opt for something more economical.

But, when it comes to an MVHR retrofit, it's likely to be more expensive again.

"Costs will depend on the complexity of the system and the size of the house and vary between £8k and £20k for large houses with 2 units," says David Hill.

"Increased costs are primarily due to the additional labour and design complexities involved in adapting the system to an existing structure," explains Russell Smith. "Costs typically include not just the MVHR unit and ducting, but also the time required to plan routes, make structural adjustments, and carry out a careful, often bespoke installation.

"That said, the expense can be offset when MVHR is incorporated into a broader whole house retrofit, particularly one that includes improvements to airtightness and insulation," he says.

Is my home suitable to retrofit MVHR?

Although each home will need to be assessed on an individual basis, Russell Smith and David Hill share some examples of homes that have successfully been retrofitted with MVHR.

Mid-terrace Victorian property upgraded with MVHR

"One notable example or a project is a mid terrace Victorian property undergoing a deep retrofit to improve energy performance and comfort," says Russell. "The house presented typical challenges – solid walls, limited service voids, and the need to preserve the building’s character.

"We took a whole house approach, improving airtightness and insulation levels first, which made the MVHR system viable and more effective. Ducting was carefully routed through the loft and dropped down through built in wardrobes and boxing in corners of rooms.

"We coordinated closely with joiners and builders to create hidden routes behind new fitted furniture and ceiling voids. The result was a discreet, efficient system that provided excellent ventilation and heat recovery without compromising the home’s aesthetics. It was a complex job, but it demonstrated how thoughtful planning and collaboration can make MVHR retrofits a success."

Sustainable design principles required whole house renovation

David Hill shares a recent scheme where the homeowners were keen to do all they could to create their future dream home in terms of sustainable design based on proven technologies.

"As well as installing a ground source heat pump for space heating and hot water, solar panels and a Tesla Powerwall 2 to generate free electricity, the owners wanted to retrofit MVHR to provide a healthy home and reduce running costs," explains David.

To make the retrofit possible and effective, a number of different techniques were employed," says David, including:

• small areas of dropped ceilings
• hiding vertical ducts in the back of built-in wardrobes
• increasing the size of soil & vent boxing to conceal ducts
• oversizing of timber studs to again hide vertical ducts
• accepting longer duct runs than normal to work with existing floor joist runs
• getting the engineer to accept some holes in steel beams in difficult locations

When a retrofit MVHR might not be feasible

While MVHR can be retrofitted into many types of homes, there are certain situations where it may not be the most suitable solution.

"Homes that are particularly leaky or poorly insulated, such as older properties without substantial fabric upgrades, may not benefit fully from MVHR, as the system relies on a good level of airtightness to work efficiently," warns Russell Smith.

"In these cases, natural ventilation and extract only ventilation might be more appropriate until the building fabric is improved. Similarly, properties with very limited space for ducting, such as some flats or listed buildings with strict conservation requirements, can pose significant practical and regulatory challenges.

"However, even in these scenarios, decentralised MVHR or hybrid systems may offer a workable alternative. Ultimately, it’s not so much that MVHR should be avoided entirely, but that its feasibility depends on the home’s condition, constraints, and the scope of the retrofit," says Russell.

FAQs

Are there alternatives to a retrofit MVHR system?

"Yes, there are alternative measures that can help achieve similar outcomes to MVHR, particularly in homes where full system installation isn’t practical," says Russell.

"One option is to improve natural ventilation by adding trickle vents and using strategically placed core vents to encourage cross ventilation. For more controlled solutions, demand controlled extract ventilation (DMEV) or continuous mechanical extract systems can help remove stale, moist air from kitchens and bathrooms while maintaining reasonable air quality.

"These systems are often simpler to install and less invasive than MVHR. Pairing them with airtightness improvements and high performance windows can significantly enhance indoor air quality and reduce heat loss," he says.

"While these alternatives don’t offer the same heat recovery benefits as MVHR, they can still contribute to a healthier, more energy efficient home when used as part of an integrated retrofit strategy."

"If you were not looking at carrying out major renovation works but still want to improve your air quality to reduce mould, humidity and co2 levels then whole room or even two room through the wall solutions are an option," adds David Hill

"They tend to be cheaper to install than whole house MVHR but the downside would be that it’s not a fully filtered system and it doesn’t have the power of MVHR to extract from larger rooms."

Is a retrofit MVHR worth the disruption?

"While the upfront investment may seem high, the long term benefits, such as improved indoor air quality, reduced heating demand, and protection of building fabric, can make it a cost effective component of a comprehensive energy efficiency upgrade," says Russell Smith.

"If you want humidity kept at below 50%, CO2 levels below 500 ppm, pollen and allergens kept to a minimum, and a system that is barely noticeable in use, powerful enough for a whole house and adapts to house conditions, then MVHR is absolutely the way to go," agrees David Hill.

Still looking to understand why you might go to the expense and disruption of retrofitting MVHR? Find out how installing MVHR completely stopped condensation in Homebuilding & Renovation's energy expert David Hilton's home, and while there aren't many, also make sure you are fully aware of the few disadvantages of MVHR.

A Positive Input Ventilation (PIV) unit causing damp in your home can be confusing. After all, the purpose of PIV is to reduce moisture, improve air quality and prevent mould and condensation. So why does damp sometimes still appear?

In many cases, the issue comes down to installation, airflow balance, or how suitable the home is for this type of system. Below, we explain the most common reasons a PIV system may contribute to damp and what you can do to resolve it.

Why can a PIV unit cause damp?

When correctly installed and used in a suitable property, a PIV system should help reduce damp rather than create it. Problems usually arise when air movement through the home is restricted or poorly managed.

PIV unit types work by gently introducing filtered fresh air, typically from the loft, and pushing stale, moisture-laden air towards the outside of the building. Ideally, this moist air escapes through background ventilation such as trickle vents, wall vents or natural leakage points.

If there is nowhere for the air to exit, moisture can become trapped around colder surfaces such as external walls and windows. This can lead to condensation forming, which may eventually result in damp patches or mould growth.

Another issue occurs when moist air is forced through gaps, cracks or penetrations in walls instead of being vented outdoors. In homes with insulated walls, this moisture can become trapped within the building fabric, increasing the risk of interstitial condensation and hidden damp problems.

Ways to stop a PIV unit causing damp

If a PIV system is contributing to damp, it’s important to act quickly.

The first step is ensuring that air can circulate freely throughout the home and escape to the outside. Without adequate exit routes, moisture will remain indoors.

In older homes, air often escapes naturally through gaps and cracks in the structure. While not energy efficient, this reduces the risk of moisture becoming trapped. Newer, well-insulated homes are much more airtight, which means planned ventilation becomes essential.

To address the problem, you may need to:

• Seal unnecessary gaps and cracks in walls and ceilings
• Install trickle vents in windows
• Add dedicated wall vents where needed

At the same time, it’s important to prevent moist air from circulating into unwanted spaces such as lofts or cupboards. Loft ventilation, service penetrations and cupboard doors can help ensure moist air exits the home rather than condensing elsewhere.

If damp problems persist, a professional assessment can determine whether your home is suitable for a PIV system or whether an alternative, such as Mechanical Ventilation with Heat Recovery (MVHR), would be more effective - particularly in modern, airtight properties.

Try these PIV units and accessories to ventilate your home

Will a PIV unit stop loft condensation?

A PIV unit alone will not solve loft condensation if the loft itself is poorly ventilated.

Because most PIV systems draw air from the loft, that space must have adequate ventilation. Without it, moist air can build up and condense on cold roof timbers and surfaces.

Installing eaves vents or roof ventilation can improve airflow in the loft. Combined with the continuous movement of air created by a PIV system, this can significantly reduce condensation problems.

Do PIV units work if windows and doors are closed?

PIV units do not rely on windows or doors being open, but air must still be able to move freely through the home.

To allow this:

• Internal doors should have small gaps at the bottom
• Windows should be fitted with trickle vents

If air cannot travel from the centre of the house to the outside, moisture may become trapped indoors, reducing the effectiveness of the system and increasing the risk of damp.

FAQs

Is a PIV unit better than a dehumidifier?

Both systems aim to reduce moisture, but they work differently. PIV units improve whole-house ventilation and air quality, running continuously with minimal maintenance. Even the best dehumidifiers are only more suitable for tackling high moisture levels in specific rooms and require manual emptying or drainage.

Does PIV make your house cold?

Because a PIV system introduces fresh air, there may be a slight cooling effect. In well-insulated homes, this is usually minimal. If cold air becomes an issue in winter, a PIV unit with an integrated heater can gently warm the air before it circulates.

Can you turn off a PIV unit?

While it is possible to turn off a PIV unit, doing so reduces its effectiveness. These systems are designed to run continuously. More advanced models use sensors to adjust airflow automatically, maintaining efficiency throughout the year without manual intervention.

Positive Input Ventilation is just one part of an effective home ventilation strategy. In areas such as kitchens and bathrooms, local extraction - such as a properly sized extractor fan - may still be required to manage moisture at its source.

EDITOR’S NOTE: An earlier version of this article included a quote from a purported expert whose credentials we have not been able to verify. The quote has been removed. We regret this lapse in our verification process and have updated our internal protocols to reduce the risk of recurrence.

A conservatory is the perfect place to relax and take in garden views, but when summer rolls around, these spaces can quickly feel more like a sweltering greenhouse than a tranquil retreat. All that beautiful glazing might flood the space with natural light, but it also traps heat, making it tricky to keep temperatures comfortable when the mercury rises.

Thankfully, you don’t have to abandon these rooms entirely when the sun’s out. Whether you have a traditional or modern conservatory design, there are plenty of ways to keep a conservatory cool without sacrificing that bright, airy feel. From ventilation tricks that maximise airflow to smart blinds and cooling floors, a few clever updates can make all the difference.

How to keep a conservatory cool in warm weather

Without the right cooling measures in place, your conservatory can quickly become uncomfortable during the warmer months. Below, we’ve rounded up expert-backed ways to stop your conservatory from overheating, so you can enjoy it all summer long.

1. Improve ventilation 

One of the simplest and most effective ways to keep a conservatory cool is with natural ventilation. Instead of relying on mechanical cooling, maximising the room's airflow helps fresh air circulate while pushing out excess heat.

"To ensure a comfortable conservatory year-round, it’s essential to incorporate sufficient ventilation to account for the warmer summer months," explains Lisa Morton, director of Vale Garden Houses. "We advise clients to integrate ventilation in two key areas: the side frames and roof space. This helps to create a natural circulation of fresh air, drawing in cooler air at a lower level and allowing warmer air to escape from above, which will prove invaluable throughout the hot summer months."

Allowing cooler air to enter at a lower level while warm air escapes through roof vents, helps you to maintain a much fresher conservatory without the need for costly cooling systems.

2. Install thermal blinds for shade

Once heat gets trapped inside a conservatory, it can be tough to shift, so the best approach is to stop it from building up in the first place. The right window treatments make all the difference, keeping harsh sunlight out while still allowing soft, natural light to filter through.

"Good quality window treatments such as lined curtains and blinds are worth the investment," explains Debbie Leigh, design manager at ILIV. "They offer temperature control and privacy year-round. Blackout and thermal linings also help to keep a conservatory cool in summer by blocking out unwanted light."

For a flexible option, thermal-lined roller blinds reflect heat away while letting you adjust the light levels throughout the day. Pleated blinds, with their specialist reflective fabric, are another great pick, bouncing the sun’s rays straight back out. If you prefer an unobstructed view, solar-control window film – such as this heat reflective window film from Amazon – can help reduce heat and glare without covering up the glass.

Top Tip: To get the most out of your conservatory blinds, close them before the midday sun hits. Letting the sun stream in early might seem appealing, but once the heat builds up, it’s much harder to cool the space down. Keeping the blinds drawn during the hottest hours of the day will help keep your conservatory feeling fresh and cool.

Shop conservatory blinds

3. Upgrade your glazing to keep the heat out

If your conservatory feels more like a greenhouse on even moderately sunny days, outdated glazing could be the cause. Older conservatories, especially those with single-glazed or untreated glass, trap heat far more effectively than they let it escape. Upgrading to modern, energy-efficient glazing can make a huge difference, helping to keep your space cool in summer and cosy in winter.

One of the best options is solar control glass, which reflects excess heat while still allowing plenty of natural light to flood into your home. If a full glazing upgrade isn’t in your conservatory conversion budget, UV-coated window film is a great alternative, as it works to reduce glare and heat absorption without blocking your view. And if you’re planning a new conservatory, double or even triple glazing is well worth considering, helping to maintain a comfortable temperature all year round.

4. Choose Conservatory Flooring Wisely 

While ventilation, glazing and blinds are all fairly obvious ways to cool down a conservatory, flooring plays a surprisingly big role in keeping these rooms comfortable. Certain flooring materials absorb and trap heat, causing a space to feel hot and stuffy, while others help to regulate temperature naturally.

"Conservatory flooring needs very careful consideration as it’s expensive to replace if you get it wrong," says Mervyn Montgomery, joint-founder and managing director of Hampton Conservatories. "Conservatories are a sun trap, and although modern conservatory designs use new technologies and building techniques to maintain a cool ambient temperature inside, the choice of flooring can make a big difference. Opting for a naturally cooling material, like porcelain tiles, can reduce the risk of the floors heating to an unmanageable level."

Natural stone, such as limestone or slate tiles, is another great option, as these types of floors stay cool underfoot, even on the hottest days.

5. Use Fans or Air Coolers to Circulate Air

Sometimes, even with the best ventilation and shading in place, a conservatory can still feel warm and stuffy. That’s where the best fans can make all the difference. A tower or pedestal fan will help move air around, preventing warm pockets from settling, while a ceiling fan (if your conservatory has the height for one) can draw hot air up and out of the space.

If your conservatory still holds onto the heat in the evenings, positioning a fan near an open window can help draw in cooler air from outside, giving the space a much-needed break from the day’s warmth.

6. Style Your Conservatory Interiors for a Cooler Feel

Your conservatory interiors can have a bigger impact on temperature than you might expect. Heavy, dark fabrics absorb heat, making the space feel warmer and stuffier, while light, breathable materials like cotton and linen help create a fresh, airy feel.

When considering furniture, rattan and wicker are great options, as they allow air to circulate, keeping the space naturally cooler than solid wood or upholstered pieces. Even houseplants can lend a helping hand. Peace lilies, areca palms, and rubber plants not only look fantastic in conservatories and sunrooms, but also help regulate humidity, releasing moisture into the air to create a more comfortable atmosphere.

7. Upgrade or Replace Your Conservatory Roof

If you’ve tried all of the above techniques and your conservatory still overheats in summer, the problem may be the roof itself. Older polycarbonate and single-glazed roofs trap heat during the day but lose it quickly when the temperature drops. Swapping to a tiled, solid, or hybrid roof can provide better conservatory roof insulation, helping to maintain a more consistent temperature inside.

“Even with modern technologies and methods to reduce excessive sunlight and inconvenient glare, you may still want to opt for a solid conservatory roof design," says Mervyn Montgomery from Hampton Conservatories. "These designs allow for additional shading during the summer months and a cosier feel during the winter."

If a full conservatory roof replacement isn’t an option, insulated roof panels can be retrofitted to reduce temperature fluctuations without the need for any major renovation work.

If you also struggle with a chilly conservatory during the colder months, it's worth noting that thermal blinds and high quality glazing can also help heat a conservatory in winter.

Condensation, damp and mould are all unwanted intruders in your home and Positive Input Ventilation is one way to help combat the issue. The right PIV unit type will help push clean air through your home and get rid of the old stale air. It’s this process that helps reduce the chances of mould and damp making an appearance.

Positive Input Ventilation can be installed in any home, but which type you choose will depend on the property you live in. Here ventilation experts reveal the different types of PIV units available on the market and which one will work best for your home.

PIV unit options

(PIV) Positive Input Ventilation units while performing the same task are available in different types. These are typically used in different property types to get the best performance. Here, Thomas Oldham, Co-Founder, UK Construction Blog gives a quick overview of the different options.

Loft-mounted units

The most common type, installed in the loft space to draw in fresh air from outside and filter it before distribution throughout the property.

Wall-mounted units

Designed for properties without lofts, such as flats. These are fitted directly to an external wall.

Heater PIV units

Include built-in heating elements that warm incoming air during colder months, preventing cold draughts.

Loft units are among the most commonly used PIV options. Positive Input Ventilation (PIV) units are typically installed in the loft, with the diffuser mounted on the ceiling directly below. This setup simplifies installation, allows the system to use fresh air drawn in from roof vents, and helps keep noise and clutter to a minimum.

While basic loft PIV units are popular, many systems come with integrated heaters to warm the air before it circulates, reducing cold draughts in winter. Some models also include sensors to automatically adjust the heater based on air temperature, improving efficiency. More advanced units may feature hygrometers that adjust airflow according to humidity levels, ensuring optimal performance.

The cost of PIV units varies depending on features. Basic loft units typically range from £200 to £300, while models with heaters, sensors, or central control panels can cost between £400 and £1,200.

For homes without loft space, wall-mounted PIV units are a practical alternative. These units operate similarly to loft systems but draw fresh air from outside. They are best positioned on an external wall to minimize the amount of ducting required. Prices for wall-mounted PIV units generally range from £150 to £500, with compact, quiet-running models with integrated heaters at the higher end of the scale.

Try these PIV units to ventilate your home

How to look after PIV units

PIV units are generally pretty simple to look after and costs are minimal as Oldham shares, “One of the most significant advantages of PIV systems is their minimal maintenance requirements compared to dehumidifiers and air conditioners. They are fully autonomous systems requiring virtually no maintenance.”

The only maintenance is a regular service as Oldham continues, “Regular servicing involves filter replacements every three to five years, depending on installation location and environmental factors.”

And, the cost is negligible, “These filters typically cost £20-£40,” adding, “With service visits ranging from £80-£150 if professionally replaced.” Replacing a filter is a task that you can take on yourself, just remember to get the right filters for your PIV unit.

Can I install a PIV unit myself?

Installing a PIV unit can be tackled on a DIY basis, but if you have never done it before there is a lot that can be missed. Ideally you want to call in a professional as Oldham shares, “Whilst PIV units can technically be installed on a DIY basis, professional installation is strongly recommended.”

He goes on to say, “This is because components need installation in hard-to-reach locations such as lofts, systems require connection to mains electricity, which must be done by competent installers.”

A poorly or incorrectly installed PIV unit will prevent a property from appreciating the full benefits.

No-one wants condensation in the home and the right ventilation helps make sure its doesn’t take over and lead to mould and damp issues. Check out our building regulations Part F to see how regulations can affect a remodel and what your minimum house temperature should be.

EDITOR’S NOTE: An earlier version of this article included a quote from a purported expert whose credentials we have not been able to verify. The quote has been removed. We regret this lapse in our verification process and have updated our internal protocols to reduce the risk of recurrence.

If you're considering building a kitchen extension, you may be wondering if your kitchen extension ventilation needs a different approach to the measures you'd take for a standard kitchen.

Perhaps you're asking if you need different types of ventilation or can you use similar products? Or, if you're taking an open-plan approach to your kitchen extension does this change things?

We asked extension experts for their recommendations for getting your kitchen extension ventilation right, and here's what they have to say.

1. Why does a kitchen extension need ventilation?

The reality is you need ventilation throughout your whole house which means when designing an extension for any purpose, you will need to take into account any additional ventilation needs and requirements. However, in the case of your kitchen extension ideas, the need is even greater.

"All extensions will need some passive or natural ventilation," confirms Daniel McMurtry, sales manager at Simply Loft, "but as kitchens are prone to moisture from cooking, dedicated active ventilation such as cooker hood extraction, and natural ventilation, is vital."

2. Is kitchen extension ventilation different?

Kitchen ventilation for any room where you cook involves making sure you have a number of ventilation requirements in place in order to combat mould, moisture and odours. Natural ventilation and the best kitchen extractor fans should all form part of your final design, but how does this differ from kitchen extension ventilation?

"Both are covered by the same regulations, which is Part ‘F’ of the UK building regulations," advises Daniel McMurty, "however the size of the kitchen extension in relation to the existing property, the amount of glazing, and the number of people likely to use the space will have an impact on the ventilation needs."

"Kitchen extension ventilation can differ to standard kitchen ventilation due to the specific characteristics and potential challenges associated with extensions," agrees Gregory Smith, property expert at Price Your Job. "Extensions are usually larger in size and have spaces with altered layouts which could create a less natural airflow. This may result in the need for more robust mechanical ventilations.

"If you are extending your kitchen, you could also be looking to cook more or engage in more intensive styles of cooking," he suggests. "This could lead to higher levels of cooking fumes, steam, or odours, demanding more powerful ventilation.

"As a result, the building regulations for extensions may impose stricter ventilation requirements to ensure compliance," says Gregory. "Newer extensions can have different air tightness properties and this can increase the risk of condensation if ventilation is inadequate, so it is important to add the appropriate levels of ventilation as needed."

Opting for a kitchen extension with a lot of glass such as an orangery kitchen extension could also make overheating potentially an issue, which is why regardless of the type of extension you are adding, it's important to make sure your kitchen extension ventilation is taken into account by both your architect and kitchen designer when planning and designing the new heart of your home.

3. Types of kitchen extension ventilation

Ventilating your kitchen extension well is achieved by combining a number of different types of ventilation.

"A combination of mechanical extraction, trickle vents which are small vents in window frames, purge ventilation such as opening windows or skylights, and positive input ventilation that pushes fresh air into a building can all be used in combination to satisfy your kitchen extension ventilation needs," says Daniel McMurty.

"You will first of all need an extractor fan or range hood," explains Gregory Smith. "This will directly remove cooking fumes, grease and steam from above the hob or range. It’s important to ensure the extractor fan’s capacity is appropriate for the size of the kitchen and the type of cooking that you do. Powerful cooking styles such as grilling or frying will require a higher capacity.

"Natural ventilation is also important," he confirms. "Make sure there are large, openable windows. These will allow fresh air to circulate and help remove odours and steam. Also make sure there are doors leading to the outside or other well-ventilated areas as these will also contribute to natural airflow.

On the rare occasion you can't vent externally (unlikely with a kitchen extension being newly built and having external walls), "choose a recirculation/filter cooker hood system which will remove oily particles from the air and create a circulation of air," says Daniel, "but combine it with purge ventilation or PIV to help remove excess moisture from the room." Natural house cooling ideas can all help too, which could involve using more window shading than you'd originally planned as one example.

Alternatively, if you are extending a terraced house with a rear extension but the kitchen will be located in your existing home meaning there isn't direct access to an external wall, choose an extractor system that can be ducted through the ceiling or walls to the closest external wall.

These extractor fans will provide mechanical ventilation in your extension

4. How to design kitchen extension ventilation

When finalising the design for your kitchen extension ventilation, there are a number of ways in which you can ensure your kitchen layout ideas and ventilation work together to get the best end results.

First on the list is thinking about where your external vents or ducts will be running. "Position cooker hood extractors to allow the shortest possible ducting run to the outside," says Daniel McMurty. "The shorter the ducting the more effective the ventilation.

"A longer run will require a more powerful extractor which will generate more noise and typically use more power," he explains.

"You should prioritise ducted extractor fans that vent directly outside as this is the most efficient method for removing cooking fumes," says Gregory Smith. "Position the hob and extractor fan as close as possible to an external wall to reduce the ducting distance and use the recommended duct diameter for your extractor fan to ensure adequate airflow.

"Make sure to incorporate large, strategically placed windows that can be fully opened to help with ventilation," he adds. "Consider also installing bi-fold or sliding doors that open onto a patio or garden as this will allow for maximum airflow.

"Skylights can also help with ventilation if you choose ones that can be opened. Make sure to design the layout to encourage cross-ventilation and for the best airflow. For example, place windows and doors on opposite walls to create airflow," advises Gregory.

FAQs

Will opening up the whole of the ground floor make a difference to kitchen extension ventilation?

"Yes it does," confirms Gregory Smith, "as this type of layout creates a much larger volume of air that needs to be ventilated. This means that a normal extractor fan may not be sufficient. Steam, grease and cooking fumes can travel further as there are no walls blocking the air from spreading.

"The steam and moisture from the kitchen area can also spread into the adjacent rooms and this can increase the risk of condensation and mould growth in other areas of the home.

"An open-plan extension often results in you needing a whole-house ventilation strategy such as a Mechanical Ventilation with Heat Recovery (MVHR) system. This can provide balanced ventilation throughout the combined space, ensuring consistent air quality and preventing condensation," says Gregory. Noting again the importance of natural ventilation and making sure your plans adhere to the latest building regulations.

Can I extend my MVHR system into a new extension?

"Yes, you can extend an existing MVHR system to a new extension," says Daniel McMurty, "but it requires careful planning to ensure proper ductwork design and system capacity to handle the additional space. You should consult with a qualified ventilation specialist to assess the feasibility and best solution for your home."

Still in the design stage of planning your extension? Find out how much an extension costs and check out these kitchen extensions with skylights as a means of improving the airflow in your kitchen extension ventilation.

We put our kitchen extractor fans through a lot. Or rather, we put a lot through them. Years of fan-powered fume extraction or purification wears out these appliances. As a result, kitchen extractors often need to be replaced within around 7-10 years.

There’s plenty to consider when replacing a kitchen extractor fan. You need to choose the right replacement extractor, safely uninstall the previous unit, and then install the new extractor – probably working with a kitchen layout that was designed around the previous kitchen appliance.

To help you get this right, we interviewed Harry Young, an extractor fan specialist and Director of ExtractorFanMan.co.uk, and Clive Holland, a DIY expert and presenter at Fix Radio. Read on for their advice on kitchen extractor replacement, from choosing the right new model to working with existing ducting and electrics.

Choosing the right kitchen extractor fan

Replacing a kitchen extractor is an opportunity to improve the appearance, condition and air quality of your kitchen. It pays to choose your replacement model carefully.

Harry Young, Director of ExtractorFanMan.co.uk, advises that it’s crucial to consider the new unit’s extraction rate.

“It is advisable to follow building regulation part f guidelines and install an extractor which meets these minimum levels, but above all I would suggest choosing an extractor that can provide you with at least 15 air changes an hour when extracting externally,” says Young.

“To calculate this, you need to work out the volume of air in your kitchen. For example, a 3m by 3m kitchen with a ceiling height of 2.4m would be calculated as 3 x 3 x 2.4 = 21.6m3 of air volume.

“Multiply this by 15 changes an hour = 324m3/h, meaning you would want to choose an extractor that has this level of extraction as a minimum,” he says.

Filter maintenance and energy efficiency are also important factors to consider.

“Charcoal filters in recirculating models need replacing every few months, while grease filters in vented extractors should be washed regularly,” says Clive Holland, a DIY expert and Fix Radio presenter.

“Also, if you’re keen on a sleek and modern look, integrated or downdraft extractors can be a good choice, but they are often more expensive,” he adds.

Recirculating vs vented: Is it easy to switch?

If you have been using your current extractor as a recirculating cooker hood, then you might consider switching to a vented system that extracts air from the building.

“The choice largely depends on your kitchen layout and personal preferences,” says Holland.

“A vented extractor which removes air directly outside is a good option for eliminating cooking odours and excess moisture. They help prevent condensation and grease build-up, which is ideal for busy kitchens where lots of frying and boiling take place. However, vented extractors require ducting, which can be tricky to install if your kitchen isn't positioned near an external wall,” he says.

Meanwhile, Holland recommends the use of recirculating cooker hoods in properties where adding ducting and a vent would be impractical.

“These models use filters to clean the air before releasing it back into the kitchen, making them easier to install and more flexible in terms of placement. They are useful for flats or kitchen islands where running a duct isn’t an option. However, they do require regular filter changes to stay effective, and they may not be as efficient at removing heat and steam as vented options,” he says.

Many of the best kitchen extractor fans can be used as either a recirculating or vented unit, depending on how you configure them.

How to ensure a new kitchen extractor will fit where an old one was installed

Young stresses the importance of choosing an extractor with parts that are suitably sized and shaped for the room.

“You may have existing ducting or an electrical connection that was in the chimney part of the old extractor – and if your new extractor has a chimney with different dimensions, these parts may be visible or in the way of fixing the new chimney, which can pose problems during installation,” he says.

The same type of problem could apply to both canopy and integrated kitchen extractors.

“The cut-out made in the kitchen unit accommodating the previous extractor may be too big or small for the new extractor, meaning alterations and adaptations would need to be made, ” says Young.

“Another point to consider is the minimum distance an extractor can be above a hob. Remember that the gap between the extractor and an electric hob must be at least 650mm, increasing to 750mm when above a gas hob.”

Try these stylish kitchen extractor fans to replace your old one

How to replace a kitchen extractor fan

Before you start any work on replacing a kitchen extractor fan, you must ensure the power to the extractor is isolated and switched off. If electrical alterations are required, get help from a qualified person such as an electrician or appliance technician.

1. Mitigate for potential damage to the kitchen

“Before attempting to uninstall a kitchen extractor, ensure that power to the extractor is isolated and switched off,” says Young.

“You should then cut away any silicone or sealant that has been applied around the edge of the extractor. Not doing this can lead to paint and plaster being pulled from the wall.

“Equally, if you have a tiled splashback, check if this goes behind the extractor, because if the tiles have been installed subsequently to the extractor, you run the risk of pulling tiles from the wall when uninstalling,” he adds.

2. Remove the old extractor unit

Uninstalling the old extractor should be relatively simple. You’ll need to unfasten the screws that secured the unit to the wall, and then lift the unit down (probably with help from another person). According to Young, it’s important to handle components carefully.

“Often the electrical connection can be located within the chimney part, so take care to avoid pulling on any wires or electrical connections,” he says.

“When uninstalling a ducted extractor, it is very easy to rip the ducting or pull it out of place. If you pull it out of place and the ducting disappears into a wall, you might have a job trying to find where it has come loose!”

3. Assess existing system components

Sometimes, you can save money and effort by reusing parts used with your old extractor – especially the duct and vent in a ducted system. However, this depends on the condition of the components.

“If you have existing ducting for extracting externally, it is wise to look inside and check if there is a significant amount of grease build up or rips and tears, and that the ducting is not misshapen,” says Young.

“Any significant deformations can reduce the airflow from your new extractor, making it work harder and ultimately reducing its lifespan. Rips in the ducting could lead to hot steamy air being released into somewhere like the wall cavity, which can lead to problems like damp.”

Before reusing existing ducting, you’ll also need to check whether it meets your new extractor’s specifications.

“Check what size ducting is recommended by the extractor’s manufacturer as this could affect any warranty – it usually ranges from 100mm to 150mm circular ducting,” says Young.

You’ll most likely be able to use the same electrical connection that powered your previous extractor with the new unit, but it’s essential to check the new model’s requirements before you connect it.

“In some cases you may need to alter the electrical outlet and install a fused connection, single socket outlet, or other type,” says Young.

“Additionally, you will need to ensure the supply you have is rated properly for the new extractor. If you do attempt any electrical work, ensure the power supply is isolated and switched off first.”

4. Install the new extractor unit

If you want detailed guidance on this step, see our guide to installing a kitchen extractor.

In short, you will need to isolate and switch off power to the relevant electrical outlet, assemble the extractor, mount it on the wall, and then either install its filters (for a recirculating model) or connect the ducting leading out of the building (for vented models).

“Take your time and be careful of hidden cables and pipework when drilling through, as kitchens can be high traffic areas for services running behind the wall,” says Young.

With ducted extractors, creating a tight connection between the extractor and the duct is crucial.

“A common pitfall is the use of incorrect ducting connectors and inadequate tape to seal the connections,” Young adds.

“Do not be tempted to use a piece of old pipe to provide a connection, as specifically made connectors (like this 100mm model) are available at very low prices and will give you better longevity. We use foil insulation tape combined with jubilee clips to ensure our connections do not come loose.”

FAQs

Is it better to get a professional to replace your kitchen extractor?

Some confident DIYers do replace their own kitchen extractor, although the complexity of the task depends greatly on the type of installation. For example, replacing one recirculating cooker hood with another is relatively straightforward, whereas adding ducting and a vent to create a new vented extraction system would be far more challenging.

“Although removing, replacing and installing an extractor fan can seem like a simple DIY task there are many pitfalls, from selection of an appropriate extractor to installation,” says Young.

“We would recommend contacting a professional to aid in replacing or installing a kitchen extractor. They may be able to give suggestions to help you improve your extraction system and will have all the various tools and sundries required to complete an effective kitchen extractor installation.”

What can go wrong when replacing a kitchen extractor fan?

According to Holland, one of the most common errors encountered during kitchen extractor fan replacement is choosing an extractor that’s not the right size for the hob.

“A unit that’s too small won’t effectively capture steam and grease, meaning your kitchen could still end up feeling hot and sticky after cooking,” he says.

“Check the extraction rate and make sure it matches your kitchen size, as bigger spaces need stronger airflow. You should also consider noise levels, especially if your kitchen is open-plan. A quieter model will make a huge difference when you’re having a conversation while cooking.”

Another pitfall to watch out for is selecting a low-quality or high-maintenance extractor.

“Don’t always go for the cheapest option just to save money, because a poor-quality extractor won’t last long and may struggle to do the job properly,” says Holland.

“Think about maintenance too – some models need more frequent filter changes than others, which can add to their long-term costs.”

Upgrading your kitchen extractor fan is one of the best things you can do for the air quality in your home. A good recirculating model will remove unhygienic particulates from cooking fumes, leaving you with cleaner air, while vented models remove stovetop fumes entirely. For more ideas to help you breathe cleaner air at home, see our guides on positive input ventilation (PIV) and air purifiers.

Mechanical Ventilation Heat Recovery (MVHR) systems have in recent years become ever more popular, especially in new build homes. They ventilate the home at the right rate, recover heat from the stale extracted air and filter the incoming air to keep the home fresh and healthy.

However, while most MVHR systems are described as almost fit-and-forget systems, with claims that you only need to check the filter 'every now and then', this is only partially true.

As with any mechanical technology there is always the chance of mechanical wear and tear, or even failure, and therefore periodic inspection and preventative maintenance is advised. But exactly how often is ‘every now and then’?

Does MVHR maintenance involve a lot of work?

As the manufacturers state, the main component of an MVHR system requiring regular maintenance are the filters. That said, it's not a difficult task or one that will take you hours.

Most of the rest of the MVHR system does not need constant maintenance, but there are some items of the MVHR system that may need periodic inspection just to check that they have not suffered with substantial wear or unusual dirt build up.

MVHR costs can be high, so you'll want to take care of your system properly to avoid any problems. It is also important to ensure ensure it's serviced regularly by a qualified professional as well as the MVHR maintenance tasks you can perform yourself.

MVHR maintenance: Filters

Most MVHR fan units will have a minimum of one set of filters. They are dust filters and could be either G3 or G4 filters. These are coarse particle filters with the G4 being slightly finer than a G3.

Other filters that are used for the supply air are F7 or F8 filters, which are very fine filters that can potentially filter fine airborne particulate such as pollen. Another filter that is often found in MVHR units is a charcoal (carbon) Nox filter. This filter potentially filters out exhaust fumes or smoke, which is particularly useful near busy roads.

The frequency of filter changes depends a lot on how much work the filter has to do, although every 3-6 months is often recommended.

It is common to change the dust filters around once or twice a year and sometimes cleaning them with a vacuum cleaner can be helpful, albeit not all dirt is dry, or loose enough to vacuum out.

The charcoal and pollen filters on the other hand are more expensive and as such, to save on costs, the pollen filters for example, can be used at certain times of the year rather than throughout the whole year.

As an example, I have G4 filters in the fan unit and then on the supply air I have a filter box with a further G4 filter as well as an F7 and Nox filter to filter the air going to the home.

Less popular, but also an option for a busy kitchen is to have grease filters in the room extract vents to prevent any dirt clogging up the heat exchanger in the fan unit. These filters are sometimes part of the ceiling vent, but for bigger filtration volumes you may need to install a plenum box, which is effectively a grill on the ceiling that has a box behind it that is hidden in the ceiling void and holds the filter.

Maintaining the filters is a fairly simple user-friendly operation. However, the fan unit should be installed in an area that is easy to reach or it simply won’t be done and your MVHR unit could then clog up with dirt and the air flow will be restricted, resulting in a humid home as well as the potential to burn out the fan motors.

Filters can be purchased from the fan unit manufacturer, but there are also many other online vendors of the filters that offer competitive pricing. Filters can be bought from 3^rd party vendors but spare parts for the fan unit should always be purchased from the manufacturer.

Shop for replacement MVHR filters

Other elements requiring MVHR maintenance

Other parts of your MVHR system requiring occasional maintenance are as follows.

Condensate drains

Any condensate drains should be periodically checked to ensure they still work and have not got blocked due to dirt buildup.

The condensate drain should have a dry trap fitted to it which is a short piece of pipe that has a rubber non-return valve in it. This lets the condensate water run to the waste pipe, but prevents smells from the waste pipe entering the MVHR system and filtering into the home.

Ceiling valves

The ceiling valves in each room can get quite dirty, especially the extract valves in the bathroom and kitchen because the air is moist and laden with airborne contaminants. Subsequently, the valves will need cleaning.

The white metal valves on your system are fairly easy to clean. They twist out of the ceiling, but be careful to only twist them by the outer rim as the inner plate can move, potentially changing the airflow and balance of the system.

Wipe them with warm water and household cleaner, but be careful to make sure you dry them to avoid rust.

Another important tip is to make sure you do not get the valves mixed up. Even though they will fit in the ceiling fittings in other rooms, they will have been adjusted and set for that particular valve. If the valves do get mixed up or readjusted, then you will need to get them rebalanced by an experienced MVHR installer with a calibrated anemometer.

Digital display

Many MVHR units have a digital display. Always check that the display is working as some have small batteries in them to run the memory. Any boost switches may also have batteries in them if they are wireless, or fitted in wet rooms.

FAQs

Does a noisy MVHR system mean it needs maintenance?

Although some claim noise is one of the MVHR disadvantages, the MVHR unit should not be a source of noise. If you notice new sounds then you may need to check with the installer as sometimes the bearings can get worn in the fan motor, which creates a breakout sound.

A fan motor replacement is a job that should be done by an experienced installer. The fan unit itself will usually have a five year warranty with the first year or two including parts and labour and the remainder parts only. Always check what is covered and for how long to avoid any nasty surprises.

As with all mechanical technologies the quality can vary between products and so does the price. The MVHR fan unit is running all day, every day, and therefore it is worth getting a good one and then making sure it is maintained to optimise its life expectancy.

Under normal design working conditions and with the basic maintenance regime followed, the MVHR system should keep you and your home fresh and healthy for many years, without you really knowing it is there.

Considering one for your self build? Find out what's involved when adding one to your design, in our guide to MVHR installation.

There’s something undeniably inviting about the crackle of a fire while you’re cooking or sharing a meal. Whether your kitchen is big or small, a log burning stove can instantly dial up the cosiness of the space. But before you fire up your plans, there are a few key factors to consider.

Proper ventilation and extraction are essential to keep smoke and odours at bay, and the size of your kitchen will influence the type of stove you choose. Don’t forget safety either – heat-resistant materials and proper clearance are just as important as the stove’s design.

To make the process easier, we turned to the experts for their top tips on choosing and installing a log burner in a kitchen. Here’s what they revealed.

Can you install a log burner in a kitchen?

"Any stove can operate in a kitchen," explains Jon Butterworth, director at Arada Stoves. "But their suitability will depend on several factors, including ventilation, room size, and safety requirements."

"To comply with Part J of the Building Regulations, specific requirements must be met to ensure the safe and efficient operation of your log burner," Jon continues. "Proper chimney or flue systems are also essential to ensure safe operation, and sufficient clearance around the burner is necessary to prevent fire hazards."

What You Need To Consider

1. Ventilation

"The single most important factor to consider when installing a log burner in a kitchen is proper ventilation," explains Chris Baines, MD at Mendip Stoves. "While all kitchens have extraction units, these can negatively affect stove performance by potentially pulling smoke back down the chimney. Therefore, independent ventilation is crucial, especially in airtight kitchens. Ensuring a good air supply to the stove is essential for efficient operation and to prevent smoke issues."

Joanna Humphreys, fire and stove specialist at Direct Stoves, expands on this: "When an extractor fan is in use, it causes a negative pressure in the room, which can pull smoke from the stove into the room. To negate this, customers must choose a stove that can be 100% room-sealed, achieved by using an external air kit. However, not all external air kits are fully room sealed, so it’s important to verify this before purchase."

A qualified, HETAS-registered installer will be able to assess your kitchen layout to guarantee safe routing and ensure your installation adheres to Building Regs.

2. Log burner size & room requirements

"A common mistake I see all the time is homeowners buying a log burner which is too big for their kitchen," explains Chris Baines. "Kitchens are generally warm places, so the usual formula to work out the kW output required (divide the cubic area by 14) may be reduced."

You can calculate the size of log burner you need by using Direct Stoves' helpful online calculator.

"Hearth size is another crucial consideration," explains Joanna Humphreys. "Most stoves in kitchens can sit on a 12mm thick non-combustible hearth, which prevents the need for additional work to build a constructional hearth into the floor. Hearths should be approximately 300mm wider and 400mm deeper than the stove body, although this can vary slightly depending on the model."

3. Health & safety

"If proper measures are not taken during installation, such as ensuring adequate ventilation and balancing air pressure, smoke ingress into the kitchen is highly likely," explains Jon Butterworth. "This not only compromises air quality but also poses health and safety risks."

When safely installing a log burner in a kitchen, it’s important to consider what the surrounding walls are made from, advises Joanna Humphreys. "Plaster, for example, is classified as a combustible material and will either need to be protected with a wall-mounted heatshield or replaced with a non-combustible material such as a cement board. Alternatively, you can select a stove with low distances to combustibles – one with a clearance requirement of around 150mm or less. Some stoves also have an optional heatshield, which can reduce the clearances required even further."

Don't underestimate the importance of fire safety either. Smoke alarms and carbon monoxide detectors should be non-negotiable. Place these devices near your kitchen to provide early warnings of potential issues, and remember to test them regularly.

Fire safety essentials

4. Positioning

"When selecting a log burner for a kitchen, consider positioning carefully," Joanna Humphreys notes. "External air intakes for room-sealed stoves work best when the stove is installed on an exterior wall, allowing the air connection pipe to exit directly through the wall. If the stove is positioned elsewhere, additional ducting may be required, but this is rarely a preferred option due to its impact on the room’s aesthetics."

"If you have a chimney breast in your kitchen, you can utilise it to make installation slightly easier," Joanna continues. "Without a chimney, you will need to install a twin-wall flue system. These systems can run externally along the building or internally through ceilings or roofs, although some homeowners prefer not to disrupt the rooms above."

FAQs

What is an external air kit for a log burner?

An external air kit supplies fresh air directly to the stove from outside, rather than drawing it from the kitchen itself. This is particularly useful in modern, airtight homes or those with Mechanical Ventilation with Heat Recovery (MVHR) systems, where internal air circulation is controlled. By connecting the stove to an external air source, these kits reduce the risk of smoke entering the room, and prevent competition for air with MVHR systems or kitchen extractor fans.

Most kitchen-compatible log burners are designed to include external air kits, but in some cases, you may need to purchase a kit separately. Your stove supplier or installer can advise you on whether an external air kit is required and/or recommend the best options for your specific setup.

Do you need planning permission to have a log burner in a kitchen?

In most cases, you likely won’t need planning permission for a log burner in a kitchen. However, if your property is listed or in a conservation area, or if the flue extends 1 metre above the roof, you may need to seek approval. When in doubt, consult local guidelines or speak with your installer to ensure your log burner is compliant.

Do I need to notify my home insurance provider about a log burner?

It’s always a good idea to inform your home insurance company if you plan on installing a log burner. Some policies may require updates or include specific clauses for solid fuel appliances, so make sure you check in advance to ensure you remain fully covered.

What are some good alternatives to a log burner in a kitchen?

If a log burner doesn’t quite fit your kitchen’s needs, there are plenty of alternatives ways to heat a kitchen to consider.

Electric stoves: With their cosy flame effects and low maintenance, the best electric log burners offer the ambience and aesthetic of a traditional wood burner without the hassle. They’re easy to install and are available in a wide range of designs that will fit beautifully into any kitchen design.

Underfloor heating: If you want warmth without taking up valuable space, underfloor heating in a kitchen is an energy-efficient solution.

Kitchen radiators: Don't overlook the benefits of a kitchen radiator - these units are perfect for adding warmth to your home while doubling as stylish design features. From compact affordable options to the best designer radiators, you’ll find a style to suit any kitchen.

Compact ecodesign stoves are a smart choice for small kitchens or homes in smoke-controlled areas. But for the ultimate indulgence, you may want to consider a double-sided log burner. These designs are perfect for connecting dining and kitchen areas in open-plan layouts.

Installing a kitchen extractor fan is a satisfying, money-saving measure that’s within the capabilities of some DIYers – although installing a ducted extractor that takes air out of the room is more difficult than fitting a simple recirculating cooker hood.

In either case, correct installation is crucial. An essential kitchen appliance, errors when installing your extractor fan could lead to structural issues or draughts, and your cooking fumes not being dealt with effectively.

To help you install your kitchen extractor fan successfully, we spoke with construction and kitchen experts to put together this step by step guide. And, if you're not yet decided on which extractor fan you need. we've got some top tips for choosing one.

Factors to consider before you start installing a kitchen extractor fan

Many kitchen extractors can be used either as a ducted extractor or as a recirculator, however depending on your preference, each will need different installation methods.

For a ducted extractor configuration, you'll need to create a circular hole in the external wall or ceiling to allow extracted air to travel through the ducting and out of the room. Recirculating cooker hoods are simpler to install but do not truly extract cooking fumes; they purify them instead.

Another point to consider is electricity. Most extractors need to be permanently plugged into a mains power outlet. If there isn’t a suitably placed socket you can use, you’ll need to get an electrician to add one to your kitchen’s circuitry.

Some of the steps explained in this article relate only to installing a ducted extractor. If you need instructions specific to installing a recirculating one, find out more in our guide on how to fit a recirculating cooker hood.

Tools and materials needed for installing a kitchen extractor fan

Before you start the process of installing the best kitchen extractor fan to suit your needs, you'll need to make sure you have these tools to hand:

• SDS drill (for installing ducted extractors; must be rated to accept the appropriate width of drill bit)
• Diamond core drill bit (for installing ducted extractors; must be the right width to match the extractor’s ducting)
• Combi drill
• Masonry drill bits
• Laser level
• Tape measure
• Pencil
• Hammer
• Extractor unit
• Ducting kit / cooker hood termination kit (if ducted)
• Sealant (if ducted)
• Screws
• Wall plugs
• Duct tape
• Gloves
• Goggles
• Ear protection
• Step ladder

Shop for tools to help with installing a kitchen extractor fan

How to install a kitchen extractor fan: step-by-step guide

Here are construction expert, Ian Smart, company director at Graline Construction Ltd's five steps to installing a kitchen extractor fan:

1. Planning

First, decide which type of extractor you want to install in your kitchen. As Ian Smart explains, there are two main types, each of which have their own pros and cons:

“Ducted systems vent air outside through an external wall and are highly effective at removing moisture and smells, but they tend to be more expensive and require additional installation work,” he says.

“Recirculating systems push air through charcoal and grease filters to eliminate smells, smoke, and moisture before recirculating the air back into the room. They are generally more cost-effective as they do not require ducting and are ideal for kitchens without direct access to an external wall.”

Once you’ve chosen an extractor, decide where you’ll install the extraction hood or inlet (above your cooker) and mark the place on the wall.

“UK building regulations state that extractors should be installed 750mm above a gas hob and 650mm above an electric hob,” says Ian.

“Ensure that the wall where the extractor will be installed has been checked for any cables, pipes, or gas lines before marking out," he adds.

If you’re installing a ducted extractor, mark the circle on the external wall or ceiling through which the ducting will channel cooking fumes out of the room. Use a laser level to ensure the marked circle aligns perfectly with the extractor hood, and make sure you won’t be drilling through any cables, pipes, gas lines or features on the outside of the building.

2. Prepare the area

Before you begin installation, ensure the electricity supply to any applicable power outlets is turned off at the consumer unit. Do not skip this step.

Installing your extractor fan will create some dust and mess – especially if you’ve chosen a ducted model. So, remove delicate or breakable objects, put down dust sheets and make sure family members and pets can keep clear.

Remember to put on some PPE, including a dust mask, goggles, work gloves and hearing protection.

3. Drill the vent hole (for ducted extractors only)

This step can be dangerous and may be unsuitable for most DIYers. If in doubt, get an experienced person to do it for you.

Using an SDS drill with a diamond core drill bit, make a hole in the external wall or ceiling (from the inside) to match the ducting for your extractor. The hole should be just wide enough to accommodate the vent.

Set up your SDS drill with a diamond core bit. The bit should be fractionally wider than your ducting. Most extractors have 150mm ducting, and in that case you’d use a 152mm bit. Check your ducting specifications to ensure you can drill to the correct width.

You will probably need a step ladder to reach the spot. Stand and drill very carefully, as the drill may jam during drilling, causing the tool to jerk backwards towards your arm or face. Apply very gentle pressure, never forcing the drill, until the hole is made.

As you drill, some brick and other debris will come away within the forming hole. Drill in stages and remove loosened material as you go (e.g. using the claw of your hammer, or a crowbar if you have one.) This will also help prevent the diamond core drill bit from overheating and deforming.

4. Install the extractor components

You’re now ready to install your extractor in the kitchen.

“Attach any mounting brackets to the wall using screws and wall plugs, ensuring they are level,” says Ian Smart.

To do this, place the brackets against the wall, check their level using a laser level, then pencil-mark the wall through the screw holes in the brackets. Drill holes in the marked places using your combi drill (in hammer drill mode) with a masonry drill bit, use a hammer to tap the wall plugs into the holes, and finally fix the brackets to the wall by screwing them into the installed wall plugs.

Connect the ducting (if present) very securely to the extractor using duct tape and/or clamps, then lift the extractor into place on the brackets, and tighten up any screws or other fixings. This is a two-person job.

Feed the ducting from the extractor to the duct hole you’ve made in the external wall or ceiling, and fix the ducting securely into a suitably sized vent on the exterior of the building.

“If there are any gaps around the ducting or mounting area, use sealant to fill them,” says Ian.

5. Electrical connections and finishing touches

You can now connect the extractor’s wiring as per the manufacturer’s instructions, which may involve wiring a plug. Make sure the power supply to the socket is turned off at the consumer unit before you plug the extractor into the socket.

Don’t attempt this step if you are not certain you can do it safely. Instead, hire an electrician to complete the task for you.

If your extractor is a recirculating model, you’ll also need to install the charcoal and grease filters before use.

Finally, turn on the extractor and test its performance. Cooking fumes from your cooker should be sucked into the extractor and up through the ducting (or through its purifying filters).

FAQs

Installing a recirculating or ducted kitchen extractor fan system will ensure your kitchen has cleaner air and is less susceptible to formation of mildew and mould, and accumulation of grease on surfaces.

However, if your kitchen requires even more ventilation, then you might benefit from installing an additional standalone electric extractor fan, such as the Vent-Axia 441628 from Amazon. Read more in our guide to getting your kitchen ventilation right.

Mechanical Ventilation Heat Recovery (MVHR) systems are designed to both improve the air quality within your home, and provide fresh warm, heated air.

But, unlike more simple ventilation products such as extractor fans or air bricks, MVHR systems are made up of a number of different components. The fan unit is the main heart of the system as it has the heat exchanger and two fans, one to draw air from the home and one to supply air to the home.

Add to this the ducting systems, condensate waste outlets and room terminals and MVHR installation is more complex than it might first appear.

How do I know? I install energy efficient home solutions for a living and added my own MVHR a few years ago. So, if you're considering it for your own home, here's what's involved in MVHR installation.

Who designs the MVHR installation?

In most projects, especially a new build home, if you're including an MVHR system, you should receive drawings of the proposed ductwork design from your MVHR suppliers.

Many MVHR fan unit manufacturers and merchants will supply these as part of the supply service. And, if you're undertaking a self-build project, the drawing will need to be modelled into the architectural and building regulation drawings at an early stage in order to take into account any structural details such as joists, steels and fire compartment walls.

In order to comply with Building Regulations Part F, it's essential to get the design right, as flow rates will also need to be calculated and the correct duct sizes specified to make sure that the system meets the requirements.

In an existing home it can be very difficult to get detailed drawings of where all the joists and services are, so these finer details may need to be finalised during the actual installation. The drawings simply give an indication of where the ducts need to go so that quantities can be estimated and air flow rates calculated.

MVHR components

Understanding the different parts needed for an MVHR installation

In order to move air around the whole home, one of the major parts of any MVHR installation requires a network of ducts being built into the structure of your home.

These ducts can either be a rigid branch design, or semi-rigid ducts, both of which will need to go back to the fan unit. The rigid branch design systems can be better suited to new build installations as the ducts are larger and do not flex.

One main ‘trunk’ will leave the fan unit to distribute air to the home, with smaller ‘branches’ teeing off the trunk to go to individual rooms. The extract system will be a similar setup, with air being drawn from wet rooms such as the kitchen and bathrooms and delivered back to the fan unit.

The main trunk could be around 150mm diameter and reduce in size to around 125mm diameter as the ducts move further into the home and need to move less air, with the smallest ducts being no less that 100mm diameter.

Because the main ducts can service more than one room it is also necessary to install silencers in the duct system to stop sounds such as television or music travelling from one room to another through the ducts.

The silencers can be near the terminals in habitable rooms such as bedrooms, but additional silencers may also be installed near the fan unit to prevent any noises from the fan unit traveling through the ducts to the rooms.

Rigid ducts vs semi rigid ducts

The rigid ducts are usually provided in lengths of 2m with around a 150mm diameter, although this can reduce down to 125mm or even 100mm at the room terminals. These rigid ducts need to be built into a complete network using joiners, elbows and T-pieces.

It's also worth noting that not all the rigid ducting is round. There are also rectangular shaped ducts that have a similar cross sectional area to the round ducts. The equivalent rectangular ducts compared to a 150mm round duct will have a 220mm x 90mm outer measurement, while the 125mm equivalent is sized at 204mm x 60mm.

Semi-rigid ducts are a bit more flexible, albeit not completely flexible, and can be better suited to more complex installations.

The semirigid ducts are usually around 76mm outer diameter and come in 50m coils that can be fed through the home, from the manifold to the room terminals.

The room terminals are then fitted to a short piece of rigid duct that is coupled to the semi-rigid ducts with a plenum elbow. They also provide a better noise attenuation as any sounds from a room would need to travel all the way back to the manifold and then all the way back down another duct to get to another room.

The manifold can also have acoustic damping built in which eliminates any potential for this type of sound transfer.

Why two ducting systems are required

To balance the home heating and ventilation, there are two ducting systems. One that extracts air from wetter rooms such as bathrooms and kitchens, and the other which delivers fresh air to the habitable rooms such as the bedrooms and lounge.

There are also two insulated rigid ducts that are connected from the fan unit to the atmosphere via holes in the roof or walls. These ducted outside terminals, which are essentially just louvred covers as you would expect on an extractor fan, should be at least 1m apart, are usually around 150mm diameter and will need a terminal fitting that fits into the duct diameter that is used on the outside of the property.

Be sure to make the contractor aware of any bespoke rendering or building materials that have been used on exterior finishes to avoid any issues with warranties.

Understanding what size fan you need

In smaller homes the fan unit could indeed be fitted in a kitchen cupboard but there would be a lot of ducting coming from the cupboard so it would be best if the cupboard extended right up to the ceiling.

For a larger home, the fan unit could be the size of a washing machine. This would ideally be installed in a purpose built plant room or possibly a large utility room.

The fan unit is also very often installed in the loft, but be aware you need to be able to access it to change any filters and also would need to insulate all ductwork and materials that were in a cold (unheated) space.

Additional services required for MVHR installation

In order to power the unit, an electrician will need to supply a switched, fused spur to the area where the fan unit will be installed, usually just below the fan unit and is the same size as a single wall plug, and the plumber will need to supply a condensate waste to the same area.

If the condensate waste is connected to a drain or soil pipe, then a dry trap must also be fitted. The dry trap is simply a short piece of pipe that prevents smells entering the home from the drain. Unlike a basin the MVHR unit will not produce condensation during summer so a standard basin U-bend trap is not acceptable as it would dry out, and smells could then be drawn into the home.

Any low lying ducts, especially if they are below the fan unit will also require additional condensate drains with a dry trap.

MVHR installation in a new build

The first part of the system to be installed is the ductwork from the fan unit to the rooms, and from the fan unit to the atmosphere. This is usually scheduled into the build programme when the roof is on, but none of the other services have been installed.

As a general rule of thumb the bigger services go in first. So, very generically, the drains are first as they need to be straight and have a constant drop, then the MVHR ductwork, then the plumbing pipes and finally the electrics.

Underfloor heating and MVHR can work well together, but can be installed at different times depending on which system is used. But, if the pipes are pinned to the underside of the floor deck, then that needs to go in before the drains.

The ducts are placed in the floor void, stud walls and roof space and are firmly held in place with metal straps to avoid any movement. The ducts are connected to elbow fittings that then protrude through the ceiling.

The ducts need to be left hanging a little bit lower than the finished ceiling height and this is often referred to as the first fix.

The physical installation of the ductwork is usually done by a small team of installers. A two or three person team should be able to first fix a three bedroom home in around three days.

The first fix of the ductwork is something a good DIY homeowner could do, but they would need to do a lot more research to know which tools to use and also what all the fittings do and how they go together. Any leaks or air gaps in the ductwork will severely affect the performance of the system.

Once the services, such as electrics, plumbing and waste systems are all done, the ceilings are installed with holes carefully cut out to allow for the ducts to fit neatly through them.

Once the ceilings and walls are constructed and mist coated, then the ducts can be trimmed back to be flush with the ceiling, the valves can be fitted, the fan unit hung on the wall and all the ductwork connected back to the fan unit.

Once the system has been fully mechanically installed it will then need to be properly balanced with calibrated anemometer equipment. The air flow rates in each room will need to recorded on a commissioning sheet which can be submitted to your Building Control officer in compliance with Building Regulations Part F.

MVHR installation in a renovation or remodel

Retrofitting a MVHR system is very difficult and time consuming, due to the amount of ductwork that needs to be hidden away in the fabric of the building.

You cannot drill big enough holes in the solid joists for the ductwork as the biggest holes allowed in joists is no more than 25% of the depth of the joist. It is also only permissible to add holes in the first 40% of a span (load bearing end to load bearing end) but not in the first 25% of the span.

To explain this further, let's assume you have a span across a room of 4m. The first 25% is 1m and the first 40% is 1.6m. Therefore, in the 4m span you cannot drill in the first meter, and you only have the area from 1m to 1.6m to drill in. The holes can also only be a maximum of 25% of the depth, so in a 200mm joist you can only drill a 50mm hole. Any additional hole must also be separated from the other hole by two diameters.

Therefore the 50mm holes must be separated from each other by at least 100mm of solid joist. In addition to this issue, finding discrete areas for the ducts to drop between floors can also be very challenging.

The main instances when it could be feasible are in a bungalow renovation where the retrofit MVHR would be very easy. Likewise, in a fully stripped back home that's undergoing a full house renovation, it may be less of a problem to find suitable routes.

The electrical work and commissioning srill need to be carried out by a qualified engineer, but if you are trying to save costs the ductwork can be installed by anyone who is confident enough to follow the drawings and make a good job of the joints.

As a member of the design team will have commissioned the system, the integrity of the work will be verified and the design liability will be signed off, however, MVHR installation is not a job to be undertaken without careful consideration. It is crucial that the ducts are properly sealed and that the routes are balanced in order for the system to perform well. Good design is essential and you will also need the system to be finally commissioned by a qualified ventilation installer with a calibrated anemometer.

You may be better opting for a full installation package from the supplier in renovation or remodel. It may cost more but you can at least be sure that they are experienced and the right fittings are being used.

FAQs

Is my build suitable for MVHR installation?

In any project where a MVHR is to be installed you need to be sure that the ducts can be installed in the home discretely and that they do not clash with any structural elements.

Proper preplanning and design is required, which means the ideal scenario for MVHR installation is in a brand new build with open web joists, steel support beams predrilled where it has been identified that ducts need to pass through them, and a purpose built, centrally located, plant room.

Interested in understanding how the benefits of MVHR translate into real life? Find out how installing MVHR completely stopped condensation in my home and start working on budgeting for your own system with our expert guide to how much an MVHR system costs. Make sure you also know what's involved in MVHR maintenance to keep your system in good working order for years to come.

While Positive Input Ventilation has many advantages in the home when it comes to controlling humidity, it isn't a 100% perfect solution.

No-one wants condensation, damp and mould in their home and PIV can help, but it may not always be the perfect fit, as Michael Zohouri, Founder of Pyramid Eco explains, “While PIV units can address certain ventilation problems, they’re definitely not a one-size-fits-all solution. Their reliance on strategic vent placement, internal airflow management, and maintenance needs makes them less practical for some households.”

Here we look at the Positive Input Ventilation pitfalls to help you decide if it is a ventilation system that will or won’t work in your home. And whether or not you should make it part of your home ventilation mix.

Positive Input Ventilation pitfalls

Positive Input Ventilation isn’t a home ventilation system that will work for all dwellings. It has plenty of pluses, but here Soper runs through some of the potential downsides that you need to be aware of if you are thinking of installing Positive Input Ventilation.

1. Initial high costs

The price of PIV units are not as budget -friendly as some ventilation options, but by the same token they are more cost effective than others as Soper explains, “The initial outlay on a PIV system can be more expensive than extractor fans, but less expensive than a centralised extract or MVHR System.”

But you won’t need to spend big on their upkeep, he adds, “Many PIV systems require minimal maintenance and maybe only a filter change, like these Nuaire Drimaster Replacement Filters from Amazon, as and when required.”

2. Not a complete solution

While PIV can be a complete ventilation solution for some properties, it isn’t for all. You often need additional ventilation options as Soper explains, “PIV can be a complete solution for some dwellings, other dwellings may require continuous extract fans as well.”

But this will depend on other factors as he continues, “This can depend on the layout, size and occupancy of the dwelling. PIV will work well with most dwellings where all wet rooms are accessible from the central hall, where the diffuser is fitted without the need of extractor fans.

He adds, “Dwellings with internal wet rooms or wet rooms remote to the diffuser, will require continuous extract fans as well.”

Try these for better ventilation around the home

3. Installation costs

Installing a Positive Input Ventilation system is not a job for the average DIYer, ideally you need a trained professional to install it as Soper shares, “Systems should be installed by persons experienced and competent to do so.” This will add to the overall cost of introducing Positive Input Ventilation into your home. A supplied unit and labour costs will be around £800-£1000.

4. Can be costly to run

PIV units are not typically expensive to run, but a heated unit will cost more to run than a basic unit (and typically an extractor fan) and will add to your energy bills. And it will depend on other factors as Soper explains, “Running costs of PIV units with a heater can vary vastly from dwelling to dwelling, and is dependent on the location, size, layout and climate.”

But, the extra costs on your energy bills can negate other maybe costly issues as Soper adds, “You will get the benefits of improved indoor air quality and reduced costs on redecoration and repair work.” Due to the reduction in mould and damp.

5. You usually need a loft

Typically you need a loft space to take advantage of Positive Input Ventilation as Soper reveals, “The most common PIV unit is a loft mounted system”. But, if you live in a flat or don't have a loft space you have to look for a different type of unit he continues, “There are also inline and wall mounted units suitable for dwellings with airtight lofts or no loft space at all.”

But these don't have all the advantages of a loft mounted PIV unit, “However, the benefits of solar gain will not be available with these products.” Solar gain is the heat gain you get in a loft in the warmer months.

6. Limited control over output

“PIV units are a fit and forget system, designed to run in a background mode and to be automatic in their functionality, " explains Soper. He adds that adding a user to the equation can be an issue, “Having a system when the end user has control over settings can cause issues if the operation is not fully understood (increased costs, noise or inadequate airflow resulting in condensation and mould).”

However, Soper shares, “Many systems now have some form of controllability for the end user if required. Wireless controllers and even app versions, making it suitable for those who do understand the operation and wish to have greater control."

7. They can make your house cold

A loft installed PIV unit draws air from a loft space, so in the colder months a PIV can make your house feel cold as it draws colder air. On the reverse side in the summer months it will draw in warmer air to raise the temperature.

Try these to help get rid of moisture and condensation

FAQs

Do Positive Input Ventilation units need regular maintenance?

Yes they do as Zohouri explains, “PIV units do require regular upkeep, even though they’re frequently recommended as low-maintenance systems.” He continues, “The filters typically need replacing every 2–5 years, depending on the air quality in your home.”

Zohouri recommends regular checks on the unit itself, “To keep the unit running efficiently, it’s a good idea to do an inspection every year or two to make sure there’s no dust or debris accumulating around the motor.”

As for servicing he suggests, “While some manufacturers recommend servicing every five years, this isn’t regular enough, especially in homes with higher levels of airborne particulates.”

What problems can a PIV unit help solve?

While a Positive Input Ventilation system can have a lot of plus points it might not always be the perfect fit for a home. Zohouri says, “Without a PIV unit, homes can face common issues like condensation, dampness, poor air quality, stale air, and even potential health concerns related to mould and humidity.”

He adds, “However, PIV units aren’t the only – or necessarily the best – solution for these problems.”

Positive Input Ventilation can work well as part of a ventilation mix in the home. But, Zohouri suggests it needs to work with other types of ventilation. “For condensation and damp, improve natural ventilation by opening windows and installing extractor fans in moisture-prone areas like kitchens and bathrooms can often be more effective.”

To improve air quality he recommends , “Air purifiers with HEPA filters can target specific pollutants and allergens, offering a more precise approach to improving indoor air quality.”

He finishes by saying. “Tackling the root causes of moisture and dampness – such as leaks or insufficient insulation – is crucial for creating a healthy indoor environment. Otherwise, you’re just fixing the symptom and not the cause.”

Ventilation in the home is all part of reducing moisture in the air. It can help tackle window condensation, which can lead to unwanted and ugly mould. Check out our guides on removing mould from walls and how to remove mould from grout in bathrooms and kitchens for a better looking and healthier home.

Positive Input Ventilation is one option for keeping away condensation, damp and mould. But, the downside is a PIV unit making your house cold. They typically draw air from a loft space where the air temperature differs from the home.

In the colder months the temperature of the air in a loft space will drop. This means that a Positive Input Ventilation unit will be drawing colder air into the home. But there are solutions to help balance out the temperatures and stop your home feeling cold. Here the experts delve into why and what you can do.

PIV making the house cold? The reasons why

A Positive Input Ventilation unit is effectively taking air from a source, typically a loft space, and pumping the air out through a diffuser which is typically found in the ceiling of an upstairs room if the PIV unit is installed in the loft.

Homebuilding & Renovating's energy expert David Hilton, owner of Heat and Energy Ltd points out that the purpose of PIV is to, “Dilute out the stale air in the whole home”. If you don’t have a PIV unit installed, the stale air can linger in the home causing issues, as Michael Zohouri of Pyramid Eco explains, “Without a PIV unit, homes can face common issues like condensation, dampness, poor air quality, stale air, and even potential health concerns related to mould and humidity.” He adds, “While PIV units can be helpful in addressing ventilation issues, there are some limitations.”

One of those is that it can make your house feel cold. Larry Soper, Technical Services Manager at Envirovent give a quick overview of the common issues, “Reasons for a dwelling not benefiting from PIV can be down to poor specification or installation, draughty buildings, single glazing, or walls, penetrating or rising damp, poor insulation, or cold bridging in the building fabric.”

He adds: "A loft mounted PIV unit filters air from the loft space and gently delivers it into a central location in the home. During the colder months, the loft space is generally 3-5°C warmer than outside air due to solar gain.”

But while the air is still warmer than the outside air, it will still be colder than the air in the home, hence the reason why a home feels cold as Hilton succinctly explains, “The issue I have with most installations is that it brings cold air into the home in winter and warm air in in summer.”

And, It's also worth noting that some PIV systems, though not so common, will use a roof vent mounted on the roof above the loft. The air that it brings in will be even colder than the air in a loft space.

Try these PIV units to improve ventilation

Solutions to stop the cold

The solution to solving a cold home initiated by PIV will depend on what the issue is. But there are some simple and straightforward actions that will help resolve the issue as Soper reveals, “Keeping internal doors closed with adequate undercuts, having a dwelling adequately heated, a PIV unit installed and set correctly should all assist in preventing the dwelling from being cold. “ Here Soper adds a few rules to follow to help lessen the cold issue a PIV unit can cause.

1. Set up correctly

It makes sense that to get the best out of a PIV unit you will need to set it up correctly as Soper says, “PIV units should be set to deliver an appropriate airflow taking into consideration size of dwelling, number of bedrooms and occupancy.”

2. Install PIV with heater

There are different types of PIV units available and if you notice the difference in interior temperatures , especially during the colder months Soper suggests you install a unit with a heater, “PIV units can have a comfort heater that will further temper the air, these are generally automatically controlled.” He continues by explaining why, “This air is then delivered centrally to the dwelling, recovering further energy at ceiling height (as warm air rises), before gently distributing around the dwelling reducing humidity and surface condensation to help improve indoor air quality and minimise condensation and mould.”

3. Get a pro to install PIV unit

Installing a PIV unit is not a job for the average DIYer, and to get the best from one its should be installed by a qualified installer as Soper shares, “PIV along with any ventilation should be specified and installed by persons competent and skilled to do so, this will ensure best performance of any ventilation system while ensuring dwellings have adequate ventilation.”

In addition to these suggestions there are a couple of other considerations to take into account if you have a PIV unit located in the loft. A simple solution is to seal up draughts in the loft space. This is especially important if you have large draughts letting in cold air. Another option is to add or upgrade your insulation if need to help reduce varying temperatures and condensation. Check out our How thick should loft insulation be guide for more insight.

Both of these will help keep a more constant temperature in the loft, helping to lessen the chances of cold air being distributed around the home.

Soper concludes by saying, “If PIV units are set up and correctly installed, the area where the air is delivered will always be slightly cooler and feel fresher” He adds, “The rest of the property should benefit from this and reduce annual heating cost by around 10%.

FAQs

Is PIV suitable for large open plan areas?

While Positive Input Ventilation has a lot of positives it is not the best choice for every home as Soper shares, “While PIV can be suitable for many dwellings, careful consideration is required, as some dwelling may be better suited with an alternative ventilation strategy.”

Zohouri reiterates the point, “PIV units tend to struggle in large open plan spaces. These areas dilute the positive pressure effect that PIV relies on, leading to uneven air distribution and diminished performance.” He adds, “For open plan layouts, alternative ventilation systems that actively circulate air throughout the space might be more effective.”

Are PIV units all the same size?

No, PIV units are available in different sizes as Zohouri shares, “PIV units are available in various sizes to accommodate different home dimensions, but getting the right size is crucial. Even larger units have their limitations”.

Here Zohouri lists the ideal sizes you’ll need for different size homes:

Small homes
A unit with an airflow capacity of around 300–400 m³/h is typically sufficient.

Average homes
Units with 500–600 m³/h capacity are a common choice.

Large homes
For larger spaces, units offering up to 1000 m³/h may be needed.

To finish he says, “It’s worth noting that bigger units often consume more energy and can be noisier, which may not translate to significantly better performance.”

Positive Input Ventilation (PIV) is just one type of ventilation that helps keep a home condensation and damp-free. Check out our Natural ventilation, Loft ventilation and Building Regulations Part F guides for more info.

Dehumidifiers are great for pulling moisture out of the air. They get rid of condensation, dust and pollen, but if you're not cleaning a dehumidifier regularly it will soon stop working efficiently. This can lead to unwanted wear and tear and higher running costs.

Even the best dehumidifiers need regular attention. For most dehumidifiers this will be making sure that the dust filter is kept free of dust and making sure water doesn’t sit in the tank. Here you’ll get expert direction on how to keep your dehumidifier clean and running smoothly.

Why cleaning a dehumidifier keeps costs down

You need to clean a dehumidifier regularly, explains Chris Michael, managing director at Meaco. “Regularly cleaning a dehumidifier is crucial for maintaining its efficiency and keeping energy costs down.”

He adds, “The air filter, also known as the dust filter, requires regular attention, as dust and dirt can accumulate, limiting airflow and forcing the unit to work harder.”

And this will lead to problems as Michael confirms, “This not only increases energy usage but can also lead to overheating or, over time, cause parts to wear out or fail.”

Try these dehumidifiers for your home

Prices correct at publication

How to clean a dehumidifier

Cleaning is very much part of dehumidifier maintenance. Here Chris Michael shares the steps to follow to keep a dehumidifier clean and working at its best. He recommends cleaning the filter every two weeks.

1. Unplug the unit

It's a simple start, but for your safety Michael says, “Ensure the dehumidifier is off and unplugged before cleaning.”

2. Clean the dust filter

Before you start you will need to remove the dust filter from the dehumidifier. Check the manufacturers manual for instructions. Once the filter is removed Michael says, “Carefully vacuum it.” He adds, “If the suction of the vacuum cleaner is too strong, you can also use a damp cloth and warm soapy water, to gently wipe the dirt away.” Note that, “The water should be no hotter than 40°C.”

3. Dry and replace

The purpose of cleaning the filter is to remove the accumulated dust. Once this has been done Michael says, “Simply dry the dehumidifier filter with a tea towel before placing it back in the dehumidifier.” If you follow these instructions Michael points out, “The air filter (if you have one) should not need replacing, except for reasons of wear and tear.”

4. Check and clean water tank

Alondside keeping the dust filter clean the tank should get a wash, but not as often as Michael shares, "The tank should be emptied regularly and cleaned once or twice a year with warm, soapy water to prevent mould and bacterial growth. Rinse it thoroughly and let it dry before reinserting into the dehumidifier."

5. Clean the exterior

To finish Michael says, "Wipe down the exterior to keep dust and dirt from entering the unit. Use a soft, damp cloth and avoid using harsh chemicals." A microfibre cloth is a good choice for this job.

Try these to help keep a dehumidifier clean

Replacing an air filter

An air filter is very much a part of a dehumidifier and will need replacing regularly as Michael explains, “In order to maintain fresher, cleaner air in the home we recommend the HEPA filter (if your dehumidifier has one; not all do) is replaced roughly every three months.”

If your dehumidifier does have a HEPA filter Michael explains the benefits, “The HEPA filter provides enhanced air cleaning capabilities, turning your dehumidifier into a combined dehumidifier and air purifier.” He adds, “The HEPA is used in addition to the air filter that comes as standard in dehumidifiers so that you can get two stages of filtration. The old HEPA filter should be disposed of.”

Avoid cleaning dehumidifier coils

Dehumidifiers have a set of coils that help turn humid air into liquid form - water. These can be delicate and difficult to reach. Michael advises against cleaning them, “We advise users not to disassemble the unit for coil cleaning, as the coils are delicate and attempting to clean them could cause damage, potentially invalidating the manufacturer's warranty.”

He suggests, “Instead, just keeping the air filter clean is the best way to ensure the coils remain in good condition, as this prevents dust buildup that could otherwise reach and affect the coils.”

FAQs

How do you clean out mould from a dehumidifier?

If you leave the bucket of a dehumidifier mould can start to grow. If it does you will need a little more patience and elbow grease than normal as Adele Brennan Home electrical buyer at Domu Brands Ltd explains, “If you’re dealing with mould and it seems harder to remove, use warm water and mild dish soap but leave it sitting for a little bit before trying to clean off the mould and residue with a sponge or cloth.”

But this method might not work for stubborn mould. If this is the case Brennan says, “You can use a mould spray to remove the stubborn residue. It is advised to leave it sitting for a while, and then you can wipe away the mould. She adds, “It is important to make sure the water tank/bucket is rinsed out properly and dried before being put back into the main part of the dehumidifier.”

It is important to note that you should not use boiling water to clean the water tank.

How often should a dehumidifier be emptied?

How often you need to empty a dehumidifier depends on a number of factors as Brennan explains, “In terms of emptying a dehumidifier, it mainly depends on the size of your model and how often you use it. If you’re leaving it to run day and night, you may have to empty it once in the morning and once in the evening.”

Obviously, if you use less then you won’t need to empty as often as Brennan shares, “If you’re using it less often, we’d recommend emptying every couple of days to make sure mould doesn’t build up.” She adds, “If you’re not planning on using it again straight away after cleaning, it is advised to dry the appliance thoroughly to further prevent mould.”

Dehumidifiers are great for removing moisture out of the air. To make sure you are using it correctly and getting the best from it check out these dehumidifier mistakes, our piece on whether dehumidifiers dry clothes effectively and dehumidifier running costs.

Kitchen ventilation is a critical part of a kitchen design. Without it you will be letting large amounts of moisture float around the kitchen and beyond. And if you don’t get rid of it, you will be left with stale cooking odours, damp walls, moist countertops and endless condensation.

There is the option to use natural ventilation, such as opening a window, but who wants to be letting in cold air, especially in winter. The alternative is to make sure that you have sufficient ventilation in your kitchen. Here the experts run through the best types of kitchen ventilation to choose, and offer a selection of smart tips to help keep your kitchen moisture free.

Why you need it kitchen ventilation

Kitchens can produce a lot of moisture, but what causes that moisture? Debra Hutt, kitchen expert at Wren Kitchens, says, “Moisture can build up in a kitchen quickly as it’s a space used predominantly for food preparation, cooking and washing up. This often involves boiling multiple water sources, which releases steam into the atmosphere.”

Joshua Warren, air treatment expert at AO.com explains the common reasons, “Cooking produces a lot of moisture, particularly when you’re boiling, steaming or frying your food on the hob. You’ll also find that your kitchen appliances like a kettle or dishwasher also contribute to an increased humidity in your kitchen.”

It’s this regular production of moisture in a kitchen that means you need a form of ventilation to ensure you keep humidity levels down and problems away as Warren shares, “Without adequate ventilation, steam, smoke, and cooking odours can build up, potentially leading to damp, mould, and even structural damage over time.”

He adds, “Furthermore, excess moisture in the air can encourage the growth of mould and mildew, which can affect both your health and the longevity of kitchen surfaces and cabinetry.” So it makes perfect sense to invest in good ventilation.

Try these to help ventilate your kitchen

The best type of ventilation for a kitchen

There are typically two types of ventilation for a kitchen as Warren reveals, “The most effective way to ventilate your kitchen is through either a cooker hood or extractor fan.” How do they work? “Cooker hoods are installed above hobs and help to capture steam, odours and grease particles before they can disperse into the air.” He continues, “You’ll find an extractor fan similarly high up with most mounted on the wall or ceiling. Again, they pull warm, humid air from your kitchen and expel this outside.”

Natasha King from Vent-Axia gets a bit more technical, “If you are installing ventilation in an existing kitchen you can choose between intermittent or continuous running fans”

What’s the difference? King explains, “Intermittent extractor fans only run on demand,” How do they work? “They are used in conjunction with background ventilation (eg trickle vents in the windows) to provide extra ventilation as required by the user. Extractor fans can also be used in conjunction with recirculating cooker hoods to help maintain good indoor air quality (IAQ).”

King continues, “Continuous fans run at a low speed and boost only when needed, helping reduce pollutants, cooking odours and moisture consistently even when cooking frequently and can be used in conjunction with recirculating cooker hoods.”

She adds, “They also help prevent mould and mildew growth by balancing humidity levels, especially in smaller or enclosed kitchens.”

And there’s one final technical point worth noting says King, “In line with Part F (Means of Ventilation) of the Building Regulations if you have a cooker hood in your kitchen and it extracts to the outside at 30l/s, then there is no need for additional extract ventilation.”

She adds, “However, if there is no cooker hood or the cooker hood doesn’t extract to the outside (a recirculating type) then, an intermittent extractor fan needs to run at 60l/s.”

How to get better kitchen ventilation

1. Choose the right hood

Debra Hutt says, “Choose a matching range hood with the right dimensions, style and power to match your stove. It should cover the cooktop completely.” She adds, “Gas stoves also often require a more powerful hood compared to electric ones. Always refer to your kitchen designer for professional advice."

2. Add an extra extraction fan

“Install a secondary extraction fan in the room itself,” suggests Hutt. Why? “To consistently filter the overall air quality throughout the room. She adds, “Use even when you’re not actively using the kitchen appliances/cooking."

3. Keep filters clean

“Clean or replace filters in range hoods or exhaust fans regularly and always refer to manufacturer's recommendation,” advises Hutt. Why? “Grease buildup in ventilation equipment reduces efficiency and can even become a fire hazard. Also, clean the hood’s surfaces and vents periodically to maintain optimal airflow, aesthetics and hygiene.”

4. Pre-emptive extraction

Natasha King offers some simple and sage advice, “If you have a cooker hood in your kitchen, turn it on a few minutes before cooking to ensure steam, smoke and odours are caught from the start.” When finish cooking she suggests, “Also leave the cooker hood running once you have finished cooking to clear moisture, pollutants and odours."

5. Double up

Joshua Warren says, “Install an extractor fan above your hob to trap any steam from dispersing in your kitchen.” He adds, “Combine this with a dehumidifier to reduce excess moisture and improve the air quality. This combo will be particularly helpful if you have a small or enclosed kitchen.”

6. Leave windows open

“Leave your windows open whenever possible as this will allow moisture to escape rather than build up,” recommends Warren. “This tip can also be heightened by leaving your kitchen door closed when you’re cooking. By doing so, you’ll prevent moisture from spreading to other rooms in your home.”

7. Couple of quick tips

Finally, King offers a couple of easy to implement tips to help reduce moisture in the air, “Keep pot lids on when cooking, this reduces steam as well as cooking food faster.” Her other tip is, “Avoid obstructing any installed ventilation since this will reduce its ability to do its job.”

FAQs

Does a kitchen have to have an extractor fan?

The answer is no it doesn’t have to have an extractor fan but it does have to have some form of ventilation as Warren explains, “While there is no strict legal requirement to have an extractor fan, UK building regulations require some form of ventilation. It’s therefore a good idea to have an extractor fan or cooker hood as this will help manage your kitchen’s moisture levels.” Another simple option is to open a window.

But it's not always that simple as King reveals, “New build properties, and retrofit projects where energy efficiency measures are implemented should all have kitchen ventilation installed in line with the Building Regulations.”

She adds, “New build properties often have whole house centralised systems installed. While in refurbished properties Part F of the Building Regulations states if energy efficiency measures are carried out an assessment will be needed to determine what, if any, additional ventilation is needed, based on the estimated impact of work.”

Why? “This is to ensure energy efficiency measures don’t adversely affect IAQ (Indoor Air Quality) by making a property more air tight. She finishes by saying, “The easiest and safest way for contractors to comply with Part F is to choose continuous ventilation.”

Do I need an electrician to fit an extractor fan?

The simple answer to this with all three experts recommending you call in an electrician. Warren says, “Yes, it’s recommended to have an electrician install your extractor fan, as this may need to be wired into the mains.” King reiterates the point, “When fitting fans in a kitchen or bathroom, the electrical installation side of the work should always be carried out by a suitably qualified person.”

Hutt adds, “If installing an extractor fan, hiring a qualified electrician is recommended to ensure safe, regulation-compliant wiring.”

How do you ventilate a kitchen without a window?

There are a few options to choose from, Warren recommends the simple and straightforward approach, “Try to use either a cooker hood or an extractor fan to help draw out steam. You can also use a dehumidifier to help manage the humidity or moisture levels in your kitchen which will help reduce damp.” For more advice check our how to ventilate a room without windows guide.

While this can work for a lot of kitchens you may need to take a different approach as King explains, “A kitchen without a window needs extra thought since often this will be an internal kitchen with no access to an external wall.”

This will mean it's not possible to install a through-the-wall fan, so King advises a different option, “Ducted solutions are often needed which require higher pressure ventilation to move the air to where you want it.” She adds, “Choose inline ventilation products where a ceiling-mounted fan is ducted through the ceiling void to extract moisture to the atmosphere.”

King recommends a Vent-Axia inline ducted ACM 150 fan (available from Amazon) and the Vent-Axia site.

As an addition to help with ventilation King suggests the following, “It is vital to ensure compliance with Building Regulations that internal doors should allow air flow through the dwelling when they are shut, by providing a minimum free area equivalent to a 10mm undercut in a 760mm wide door.”

Poor ventilation in a kitchen can lead to ugly mould spoiling your walls and ceilings. Check out our How to clean mould off wood, How to remove mould from ceiling and Painting over mould guides to help get rid of it and hide it away.

When it comes to creating a comfortable, energy-efficient home, HVAC systems play a crucial role in providing consistent heating, cooling, and air quality management.

With various types of HVAC systems to choose from – each offering different benefits and efficiency levels – it’s essential to understand how each one works and which option best suits your heating, ventilation and air conditioning needs.

In this guide, we’ll dive into the basics of HVAC systems, break down the four main types and explore the benefits they can bring to your home.

How does HVAC work?

Heating, ventilation and air conditioning (HVAC) systems circulate air throughout the home, delivering either heated or cooled air to maintain a comfortable indoor climate.

In cooling mode, the system removes heat and moisture from the air by using refrigerant to absorb indoor heat and release it outside, leaving cooler, dehumidified air indoors.

For heating, HVAC systems either:

• Generate heat: Furnaces burn fuel (like gas or oil) or use electricity to warm the air, which is then circulated.
• Transfer heat: Heat pumps transfer heat from outside to inside, even in colder weather, by using refrigerant to extract heat from the air or ground.

Ventilation systems maintain fresh air circulation, expelling stale air, regulating humidity and reducing pollutant buildup for better indoor air quality.

Products that help maintain air quality

What are the four different types of HVAC systems?

Jess Steele, heating technology expert at Best Heating, categorises HVAC systems into four main systems. These include:

• Split systems, the most common type, include an outdoor condenser and an indoor unit, typically for cooling but also capable of heating with a heat pump.
• Hybrid split systems combine a heat pump with a gas furnace, providing efficient electric heating with the option of gas heating for flexibility and cost savings.
• Ductless mini-splits, which require no ductwork and feature an outdoor compressor with one or more indoor units, allowing for precise temperature control in individual rooms – ideal for homes without ducts or for zoning.
• Geothermal systems, which Best Heating described as “highly energy-efficient and eco-friendly, using the earth’s stable temperature through underground pipes to provide reliable heating and cooling", a solution they claim that’s becoming increasingly popular in the UK.

What are the benefits of HVAC?

Jess Steele said: “Some key benefits of HVAC include added comfort, improved air quality, better energy efficiency, and increased property value."

HVAC systems offer consistent, reliable temperature control, ensuring a comfortable indoor environment year-round, regardless of the weather. They also help improve indoor air quality by filtering out pollutants and allergens and controlling humidity levels, creating a healthier living space.”

She continued: “Modern HVAC units are built for energy efficiency, reducing energy consumption and lowering utility bills while maintaining top performance. A well-maintained, efficient HVAC system can also boost your home’s resale value, making it a smart investment for property owners."

What is the most energy efficient HVAC system?

Steele says: “Geothermal heat pumps are considered the most energy-efficient HVAC option because they leverage the earth's constant underground temperature. They require minimal electricity to transfer heat, making them extremely efficient for both heating and cooling.”

She added: “Ductless systems are also highly efficient, especially for targeted heating and cooling. Without ductwork – which can cause energy loss – they’re ideal for zoning and smaller spaces, maximising efficiency.”

“Modern air-source heat pumps are another very efficient option, especially in moderate climates,” Steele explained. “They provide both heating and cooling by transferring heat rather than generating it, which significantly reduces energy consumption."

Should you have HVAC in your house?

Choosing the right system depends on factors like climate, home size, insulation, and budget.

For instance, geothermal systems are ideal for long-term efficiency but have a higher upfront cost, while mini-splits offer flexibility and targeted efficiency.

James Henley, Product Development Manager at Daikin, the UK's leading provider of HVAC systems, explain the four main factors to consider whether your home is suitable for a HVAC system.

• Home size and layout: James said, "The size and layout of your home are essential in selecting a heat pump with the right capacity or BTU output to efficiently meet your heating and cooling needs".
• Climate: He advised to "Take into account your local climate and typical temperature ranges. Certain Daikin models are optimised to perform efficiently, even in extreme weather".
• Energy efficiency ratings: James also warned to "Look at the Seasonal Energy Efficiency Ratio (SEER) and Heating Seasonal Performance Factor (HSPF) ratings", which show the system’s efficiency in cooling and heating. He said "Higher ratings mean better efficiency".
• Budget: He conclude that "Your budget is also a key factor when choosing HVAC". He said "While premium models offer advanced features and higher efficiency, entry-level units still provide considerable energy savings and comfort".

HVAC systems are a worthwhile investment for any homeowner seeking enhanced comfort, air quality, and efficiency in their living space.

Whether you're considering a modern air-source heat pump, an energy-efficient geothermal option, or a ductless mini-split for zoned comfort, choosing the right HVAC system can transform your home's environment and reduce energy costs.

For more expert advice and inspiration on creating a sustainable, comfortable home, explore our guides and stay up-to-date with the latest in homebuilding and renovation.

Exactly what is a vented tumble dryer? With the British weather being what it is, it isn't always possible to hang wet washing outside to dry and if you need bulky items such as towels and bedding to dry out fast, the best method is to pop them into the tumble dryer.

While many people worry about the cost of running a tumble dryer, if used sparingly, they can really come in handy, particularly when space for hanging laundry is limited. 

There is not just one type of tumble dryer to choose from – condenser, heat pump and vented are all options and here we explain how vented tumble dryers work as well as their advantages and disadvantages. 

What is a vented tumble dryer?

The two most popular types of tumble dryer are vented and condenser. 

"The main difference between a vented dryer and a condenser dryer is how they remove water from the machine," explains James McCartney, business development director at Appliance City. "Vented tumble dryers are more common. They feature a long, flexible hose that connects to the tumble dryer and vents the water to the outside of your home."

If you are left asking what is a condenser tumble dryer, these collect moisture from wet laundry in a container within the dryer. You will be required to empty the tank regularly.  

How do vented tumble dryers work?

If you have previously been looking at heat pump vs condenser dryers, it is important to realise that the way in which a vented tumble dryer works is quite different to either of these. 

"Vented tumble dryers draw and heat air from the room in which they are located," explains  James McCartney. "The warm air is then blown around the drum as the clothes spin. This warm air passing through the clothes causes the moisture in the material to evaporate, and the air is then vented outside through the hose. This is why the water leaves the hose as steam and not liquid."

What are the pros of a vented tumble dryer?

There are many benefits to owning a vented tumble dryer, including:

• They are cheaper to buy than condenser or heat pump models
• No need to empty a water tank
• They tend to dry clothes quicker than condenser tumble dryers

Cons of vented tumble dryers

Of course, there are also a few negatives which can, for some homeowners, mean another type of appliance could be better. Disadvantages include:

• Needs to be located near an external wall to vent to outside
• Requires a hole to be drilled in the wall for the hose

Three of the best vented tumble dryers

FAQs

How much do vented tumble dryers cost?

One of the main bonuses of vented tumble dryers is that they are generally cheaper to buy than either condenser or heat pump versions. They tend to start at around £150, rising to £400 for those with sensors that detect when washing is dry.

How can you speed up drying times?

If you are also trying to speed up the drying time of items that can't go in the tumble dryer, you may well be asking 'do dehumidifiers dry clothes?' and they can definitely help here.

In order to keep your tumble dryer running costs down, it is useful to know a few tricks to getting your washing dry quicker. Try the following tips:

• Clean the lint filter regularly
• Clear blockages and dirt from interior and exterior vents
• Keep loads small and don't overload the drum
• Make sure clothes are well spun before putting them in the dryer
• Try dryer balls - Nooril Tumble Dryer Balls from Amazon are reusable and made from organic wool

Still not convinced a vented tumble dryer is right for you? Take a look at our piece on 'what is a heat pump tumble dryer?' as these are an increasingly popular option that can help save money and energy.

If you've ever wondered what a weep vent is and questioned why you might need one, we have the answer to what this smart little device can do for your home.

If you live in an older home you’re unlikely to see weep vents in your brickwork. If you live in a new build, however, they are a standard addition. Why? Because they help remove water and keep a wall dry. But don’t panic if your exterior walls don’t have them.

The perfect time to retrofit weep vents would be when repointing brickwork. But if you have no plans to do this, call in a builder to find what you need and how much you can expect to pay. 

What is a weep vent? A quick definition

“A weep vent is a small opening in brick/block walls that is designed to let out moisture and help air circulate,” explains David Winterburn, managing director at Central Building & Welding Academy. “It’s similar to a weep hole, both are designed to allow water to drain out, but weep vents also promote airflow to dry things out faster and keep the wall’s air pressure balanced.” 

What is the purpose of a weep vent?

“A weep vent is used to help keep the building dry and healthy and prevent damp by allowing any excess water to exit the building and also let air circulate,” shares David. “They allow a building to breathe and prevent issues such as a build-up of excess water from condensation, causing damp and structural weaknesses by decay of the mortar, bricks and blocks.”

Without weep vents installed a whole host of problems can occur as David continues, “Mould and mildew thrive in damp conditions resulting in internal damp issues such as rising damp which can be costly to repair.” 

Do all walls need weep vents?

Not all walls need a weep vent installed, but common wall types such as cavity walls are in need of them. “Any cavity wall definitely needs weep vents,” explains David. “They have a gap between the outer and inner brickwork that can trap water from where the temperature inside the building is different to the outside.”

Retaining walls are another type of wall that benefits from a weep vent. “Retaining walls, where they have a build-up of soil on the back, should also have weep holes to allow excess water to escape and prevent damage to the retaining wall," he explains. But some walls do not need a weep vent. “Any internal walls do not require vents of any type, or garden walls that are on flat ground either," adds David. 

These Timloc brick weep vents from Amazon are suitable for use in a retaining garden wall. 

Where are weep vents placed?

Weep vents can be placed in various positions, “But the goal is always to ensure effective moisture management and air circulation,” explains David. "They are typically found at the bottom of the walls above the damp proof course, above all windows and doors and at regular intervals on large stretches of walls.” 

A more precise placement is given by the NHBC (National House Building Council) which states “they should be no greater than 900mm centres and are recommended to be sited at every 450mm maximum with at least two per opening above doors and windows.” 

Do all houses have weep vents?

“Not all properties have weep vents, especially old houses as they were built without cavities and weep vents and cavities have become popular over the last few decades as the building industry has evolved and we have become aware of moisture-related issues and building science improved,“ shares David.

“Some older buildings were designed with drainage passages that serve a similar purpose, even though they were not specifically designed as modern weep vents. In some older renovation projects builders are made to install weep vents to meet current Building Regulations, however, it depends on the building inspector or authority that you fall under.” 

Can you retrofit weep vents?

As mentioned previously not all properties come installed with weep vents, especially older properties. But if you are having damp problems that weep vents could help alleviate you can have them installed, or install them yourself. 

So how do you retrofit weep vents? “It is done by drilling holes through the outer layer of the wall at strategic locations, this should be at the base of the wall, above windows, or at regular intervals along the wall where moisture has been a problem,' explains David.

Once any holes have been drilled, “Specialised weep vent covers or inserts can be placed in these holes. These covers prevent pests from entering and help maintain the aesthetic of the building while allowing water and air to move freely.” 

What problems can occur without weep vents?

“If your brickwork doesn’t have weep vents, it can have several issues that could potentially arise due to the lack of air circulation and trapped water,” reveals David. “Water getting trapped inside the wall, especially in cavity walls or behind exterior masonry, without a proper way to escape the moisture can lead to several problems such as deteriorating brick, mortar and other building materials.”

But what are the issues this can cause? “Over time, this might cause the wall to weaken and potentially fail, you might also see white, powdery deposits on your walls. This happens when water moving through the wall carries salts to the surface, when the water evaporates, it leaves the salts behind.” 

Alternatives to weep vents

Weep vents are designed to manage moisture, by directing water away from a wall and promoting airflow. There are alternative options but what are they and how good are they? “Yes, there are alternatives to weep vents that can help manage moisture in walls, though they may not always provide the same level of airflow," explains David.  

“You can use ventilated dry lining, which is an interior method where a ventilated cavity is created between the wall and the interior finish. It allows for moisture to be controlled inside without altering the exterior of the building.”  

A less likely but still viable alternative is, “Pressure equalisation chambers, but these are used in more modern or high-tech applications and involve creating sections within the wall that help balance pressure and reduce water penetration.” 

If you are looking to install weep vents in your home there’s a good chance you’ll need a bricklayer to help out. 

Alternatively, if you fancy tackling the job yourself it might be a good time to also spot any bad brickwork or remove damaged bricks from the wall. 

Whether you are self building, extending or carrying our major renovation works, it is well worth designing in some natural house cooling ideas in order to keep it feeling comfortable all year round.

While people have always been interested in how to prevent overheating in homes, with global warming being an issue facing all of us, it is more important than ever to think about ways to build in design features that will keep your home cool naturally.

"2023 was the hottest year on record according to the World Meteorological Organisation and scientists have warned that 2024 is shaping up to be another record-breaking year of high temperatures," points out Becky Lane, CEO at Furbnow, a retrofit startup that helps homeowners reduce their carbon emissions.." There has never been a better time to take action and get ahead of the curve."

Here, we take a look at the best ways of keeping your house cool from a design point of view. 

What is passive cooling?

Natural cooling is very similar to passive cooling. In short, these terms relate to using methods or systems to cool a house that rely on the design of a building, using natural processes as opposed to those that use mechanical systems, such as air conditioning units. 

"The best way to prevent overheating is to plan for it with your architect at the design stage when building a new home or extension," explains David Hilton,  renewables and ventilation installer.

In short, natural cooling methods are those that are incorporated into the design of the house and its surroundings. 

In this guide, we take a look at the best natural cooling design ideas around and explain how you could make them work for you.

1. Ensure passive stack ventilation is possible

While there are mechanical ways of adding ventilation to your home in order to keep it cool, some of the most effective methods are entirely natural — such as passive stack ventilation (PSV) and cross ventilation.

"Passive stack ventilation (PSV) is a natural and low cost method of ventilating your home," explains Jeremy Brady, a chartered surveyor who spent many years working as a domestic energy assessor. "It doesn’t use electricity so you can reduce your electrical load requirements and it should be maintenance free.

"The concept of passive ventilation works on the principle that warm air rises and wind blowing across the face of your roof or walls causes negative pressure which sucks out the warm air," continues Jeremy. "So in its simplest form you could open a skylight window or a window at the top of your house. As this warm air gets sucked out at the top floor, cool air is sucked in through trickle vents in your windows and gaps around services etc. to replace it.

"Passive stack ventilation expands on these same natural principles in order to provide ventilation by way of extract vents within the wet rooms of your property such as ensuites, bathrooms and kitchens which are routed vertically to the outlet vents at the ridge of your roof. Replacement air is then supplied by trickle vents in your windows or wall vents."

If you like the idea of passive stack ventilation, then you may well love the concept of intelligent passive stack ventilation. 

"The intelligent PSV system works on the same principle but includes the addition of humidity sensing vents in the inlets and extracts. These detect humidity in the air and react by expanding or contracting which opens (increasing ventilation) and closes the vents (decreasing ventilation) depending on the humidity levels within the property," further explains Jeremy.

"These intelligent vents and trickle vents don’t require any electricity to operate as they tend to use nylon filaments within the vents that expand and contract relative to the humidity levels in the individual rooms within the property and should therefore be maintenance free. The main advantage of this system is that it will self regulate the ventilation."

2. Design in window shading

This is, perhaps, one of the most obvious ways of keeping a house cool and is a common method seen on houses in hot countries, be that in the form of simple shutters or more elaborate overhangs that form part of the fabric first architecture of a building.

Focus on the south-facing areas of your home as well as those that feature expanses of glazing and talk through the idea of roof overhangs, or a stylish brisé soleil, with your designer, both of which not only look great but also act like architectural visors for your home. 

Of course there are other options to consider too for those with existing homes, looking for quick and easy ways to keep the heat of the sun out of their houses.

“The easiest to add and most effective form of shading are blinds and shutters. A good energy tip for keeping your house cool is to close your blinds during the day and open them at night, this keeps the heat from the sun out during the day, and the cooler air in during the night," advises Becky Lane, CEO of retrofit and home energy efficiency expert Furbnow. "In terms of what to look for when shopping for blinds and curtains, we recommend double layered drapes, these are effective at keeping the sun out during summer, and the heat in during winter. You can also peel them back to single layered if you want a happy medium.”

3. Keep the exterior of your house light in colour

There is a reason there are so many picture perfect whitewashed villages all over hot countries such as Spain and Greece – they are painted in light colours to keep the interiors as cool as possible. Whether you are opting for house cladding ideas or painted render, really give thought to the materials you choose.

“Dark-coloured homes absorb about 70% of the radiant energy from the sunlight that hits the property," explains Becky Lane. "This heat can then be transferred to the interior of your home through conduction. 

"Inversely, light-coloured surfaces reflect the bulk of this energy away, stopping it from entering your home in the first place. Choosing a white, or lighter colour, to paint your home is an effective way of ensuring the heat doesn’t make its way in.

“Another tip is to install reflective foil to the underside of your roof to ensure it stops the heat being transferred in. You can do this yourself by stapling it to the ceiling of the attic, so it’s a really cost effective way of keeping extra heat out.”

4. Consider a cooling pond

Although the term 'cooling pond' sounds ever so fancy, this is really quite a simple concept.

In short, this is just a pond that is located next to the house. The air that passes over the water in the pond is cooled (just like a sea breeze) and this air is then drawn into the house by passive stack or cross ventilation (see above). In addition, any warm air passing over the water will suck up liquid moisture and absorb it as water vapour.

The water absorbed will then want to switch from liquid to gas, and it will need to pull in energy (from heat) to do this – further reducing the temperature in the house it enters. 

One other benefit – they can look pretty stunning and could even allow you to have a dip if designed as a natural swimming pool.

5. Don't neglect your landscaping scheme

It isn't just the house design that can affect how cool it remains internally – the way in which you design the garden landscaping ideas will play a part too.

If you live in a suburban area and haven't heard of an ‘urban heat island' before, let us explain. This is something that is caused by large areas of hardstanding and even other nearby buildings, which absorb heat in the day before releasing it at night meaning cool air cannot enter buildings when it normally might, as you sleep.

As well as planting plenty of shrubs and trees around your property you should also avoid too many areas of dark landscaping around your home, such as black tarmac driveways, dark-coloured patios and so on.

“A new trend we are likely to see emerge this summer season is to think outside the box – literally – and use shading," advises Becky Lane. "If you have the space, consider adding trees and landscaping around your house to offer shade. Deciduous trees are ideal as they provide the foliage to shade your house during summer, and lose their leaves in winter meaning more light (and therefore heat).” 

Keeping a house cool is just one element of building a futureproof home, but if you are about to embark on a self build project it would be very wise to familiarise yourself with Building Regulations Part O. 

Part O deals with overheating and ways to precent excess solar gain as well as to ensure new homes are built with measures in place to quickly remove excess heat from indoors.  

Alison Hammond has revealed her garage transformation that includes vented floor tiles and a personalised infrared heater.

The 49-year old 'This Morning' TV presenter recently moved house from her family home in Solihull, Birmingham, and has been busy renovating the new house, with one of the first jobs being to rectify the beige garage.

In the star's self-proclaimed "first-ever garage" she wanted something special done, and rather than opting for a garage conversion, she decided to do something unique, which we'll take a look at below.

What work was done?

The white walls were painted anthracite black whilst ribbed vented (allowing oils and liquids to pass through) and rubber black and blue tiles were installed for the flooring.

A custom logo was also installed on the floor, spelling out AH. The wall was also fitted with a personalised infrared heating system bearing the presenter's initials.

A separate area was also created for gym equipment away from a marked zone with the blue tiles for cars to park.

How was it done?

The previous ceramic tiling in the garage was taken out and the garage was cleared out to make way for the transformation.

The work was done in two days by cutting the tiles to fit the exact size of the garage floor and then hammering the tiles into place, which fit together like a jigsaw puzzle.

The infrared heater was then installed onto the wall with wall plugs, heating the garage by transmitting infrared rays around the room in what David Hilton claims is one of the best ways to heat a garage as it "heat objects rather than the air" and so "a good insulation level is not always required".

Hammond 'over the moon' with the work

Alison Hammond joyously stated about the garage transformation "I love it. I absolutely love it" in a video that amassed over 140,000 views on TikTok.

She added: "My first Garage !! I love the before and after pics . Big shout out to @garagestyleltd for coming at short notice, we love it !! You smashed it definitely recommend. Note to self: Do not clutter #garage #paidfor #love.

"What a team !! I absolutely love what the have done smooth , quick and reasonabley priced . Im over the moon."

This Morning co-worker Sian Welby commented: "Omg can I live in it! Better than my flat!"

MVHR system costs for a project will come down to installation and running expenditure – with Mechanical Ventilation with Heat Recovery designed to run all year long, once in place.

The system works by controlling ventilation by removing stale air in the home from multiple rooms and providing fresh outdoor air. It is not to be confused with MEV (Mechanical Extract Ventilation) systems, which are shown to waste around nine times more energy than its MVHR equivalent.

The ability to recover heat is what distinguishes MVHR from other ventilation systems for the home as it effectively transfers heat from the extracted stale air to the incoming fresh air. This heat exchange mechanism, which is passive in nature, keeps the inside temperature comfortable while minimising heat loss. 

MVHR systems can also help to enhance air quality for people with respiratory illnesses and allergies, as well as minimise common problems like mould and moisture build-up, as they passively dehumidify the air. 

What does an MVHR system cost?

MVHR systems are not an exception to the general price increases seen across the construction industry. Both ducting components and units consist of price-affected materials commonly used across the construction sector. 

But the good news is they are more affordable than they have been in perhaps the last decade, as the drive to achieve more sustainable homes has accelerated the technology behind the systems. Ultimately, they have the ability (when correctly designed and installed), to pay for themselves in terms of future savings.

1. Cost of the MVHR system itself

When considering system costs, it is important to distinguish between standard economy UK MVHR systems and those achieving best practice standards, which are often with Passivhaus accreditation.

The system costs for an average four-bedroom new-build home using a standard economy MVHR system, would be in the region of £3,500. However, those costs for the same property using a best- practice Passivhaus MVHR system would increase to around £7,000. At the highest end of the scale, a room-by-room controlled MVHR system with active cooling, would cost upwards of £13,500.      

It is difficult to give an exact cost based on bedroom numbers alone, as property footprints can vary significantly from build to build. Some companies offer a free online budget calculator, for example the self build ventilation store, which can give you an estimated cost for your property based on floor area.      

2. Cost of installing an MVHR system

The most important part of installing an MVHR system is the design process. Budget £300– £500 for this service and do check it’s included before you buy a package option for a unit and installation. With cost sometimes considered one of the disadvantages of an MVHR system it's important to get your figures right from the off.

Using ventilation and MVHR specialists is naturally the most expensive option, but if the budget allows and you’re looking for complete peace of mind, this may be the path for you. But with the cost of professional MVHR installers starting at £1,000 and reaching upwards of £4,000, it’s easy to see why people choose to complete the installation themselves.      

If you are competent at DIY, you can achieve a good-quality installation, provided you have a good duct layout design and some technical support. Specialist companies such as JV Ventilation provide videos at sketchfab which illustrate a typical installation and can offer remote guidance and support. 

The actual design of the duct layout and specification is best left to the professionals, but self-installation is certainly a good way to save money. You will need a qualified electrician’s input to certify the works and a trained person with calibration equipment for the commissioning at the end.

If you are considering using tradespeople (e.g. electrician,plumber or renewable specialists), ensure they have the necessary training to avoid costly installation faults. The minimum qualification should be a BPEC or NICEIC qualification as a Domestic Ventilation Installer.

3. Cost of installing MVHR in an existing property

Upgrading an existing property often results in the reduction of uncontrolled air movement, e.g. when new windows are being installed or through draught- proofing measures, external insulation works or upgrading of loft insulation etc, which can lead to condensation and mould. In fact, research shows that renovation works like these increase the ‘mould risk’ by a factor of three, so it’s vitally important to review ventilation as part of your renovation project.     

In terms of options, Positive Input Ventilation (PIV) systems can be a simple solution to force some ventilation through the dwelling and reduce the mould risk, requiring a single unit usually installed in the loft. Correctly specified d-MEV (decentralised Mechanical Extract Ventilation) systems put in bathrooms and utility rooms can also help, but MVHR, with its inherent dehumidifying properties (in the colder seasons), will be best for ensuring good indoor air quality and reduced humidity levels.     

It is possible to retrofit a centrally installed ducted MVHR system, but it depends largely on the type of dwelling and the extent of renovation works (opening up) that are being carried out, both of which will impact cost.      

Compared to new builds, the cost of the MVHR system itself will often be the same, but while retrofits will be quite varied, the installation costs will certainly be higher and take longer, adding cost. In addition, it may not be possible to carry out the installation works in an inhabited existing building, so accommodation costs should be factored in, with duration specific to each project. Retrofits with limited accessibility will require specialist advice and experience to make it viable.

If a central ducted system is too costly or not feasible to retrofit, a decentralised MVHR system may be another option, where individual ventilation units are installed in each room. This has cost and speed advantages, but the aesthetic impact has to be considered. For some homes, that may be too costly to overcome the challenges compared to the future benefit.

4. Cost of running an MVHR system

There are several factors to consider when assessing the likely running costs. Energy consumption for units can vary based on the system design, number of rooms, size of the house, desired flow rates and, of course, there’s the cost of the electricity itself. How you choose to use your unit in summer months will also affect consumption and cost – the heat recovery element can be switched off without affecting its ventilation.      

Running costs are probably lower than most people would expect. As an illustration, if you have a well-installed system for an average four-bedroom house, with typical usage of around 300kWh per year, at current average electricity prices, you can expect running costs of £156 per year, excluding your standing charge and dependent on your tariff.

5. Cost of maintaining an MVHR system

The good news is that the general maintenance of MVHR systems can be carried out by the homeowner, e.g. by regularly cleaning or changing the filters and cleaning the room and external terminals and checking for blockages. Filters can be bought from about £20 per pair, but can be as much as £120 per pair depending on the brand of unit and size. They should be changed every 6-12 months, with higher pollution areas requiring more frequent replacements.     

A more detailed cleaning regime is recommended every two years, e.g. rinsing the heat exchanger and cleaning the fans. Again, for people who are hands-on, these are straightforward tasks to undertake.     

Alternatively, there are companies that offer an MVHR maintenance service, ranging from general annual maintenance starting from around £150 to a professional service starting from around £300. A professional service by an MVHR technician is generally recommended at least every five years.

It is also important to check the manufacturer servicing requirements for your system, as these are likely to form part of the terms of the warranty.

FAQs

Will MVHR save me money on heating bills?

MVHR systems are ventilation systems, as opposed to heating systems, but their ‘heat recovery’ element means they can potentially save you a significant amount on your heating bills. 

Variables will obviously come into play, such as the energy efficiency of your chosen system, the building design and insulation, local climate and user heating demands. 

Generally speaking, when installed correctly, these systems should recover more energy than they use. Predictably, the quality of your chosen system will dictate the level of heat recovery achieved. The higher-quality units have the potential to recover up to 90%of the heat that would otherwise have been lost in your home, as opposed to around 70% or less for the lower-quality units. The savings come from not having to pay for the cost of the heat you would have been losing without MVHR – up to as much as 25% of your bill.

Exactly how much you can save is directly related to the airtightness of the building – greater airtightness means a more efficient system and bigger savings. At 5m3/hr/m2 it starts to work but your heating bill savings are likely to be less than 5% per year. At 3m3/hr/m2, savings could get to 20%. These calculations need to be carried out by an expert and will be included in a professional design. 

How can I cut the cost of installing MVHR?

We’ve considered self-installation above as a way of significantly reducing costs and we’ve looked at decentralised systems as cheaper options for retrofits, but there are other ways to keep costs as low as possible for an MVHR system.      

A professional design is key to this. Architects and installers usually rely on MVHR suppliers when it comes to designing the ductwork and components. It takes specialist experience and knowledge to plan suitable pipe diameters and the most efficient way of routing, which JV Ventilation advises is critical for minimising operating speeds and energy consumption as well as reducing the amount of ducting and wastage.      

Reducing the quality of your MVHR system can always achieve cost reductions, but there may be unacceptable consequences. Make sure that you always consult with a specialist, as there are ways to do this successfully. Specialist supplier Paul Heat Recovery advises that if your budget does not actually allow for a high-quality MVHR system, corners should not be cut on the quality of ducting and noise attenuation. The ducting system is often hidden away in ceiling and wall spaces and will probably never be replaced as long as the building stands, whereas with a cheaper MVHR unit this could be replaced after a few years.   

What problems are there with MVHR systems?

Always check the exact specs of the MVHR unit, ductwork and attenuators (silencers) required, don’t just rely on blanket phrases, such as ‘high standard’, ‘premium system’ or attractive performance percentages that are self-certified or at an unusually low cost. Poorer-quality MVHR units can generate incorrect efficiency ratings in some tests, as they are not properly insulated or airtight and therefore more influenced by the room temperature.      

Watch out for underspecified ventilation rates, which can lead to poor indoor air quality. Stefan Huber, managing director at Paul Heat Recovery warns this can be a common problem. “Designs that only apply the required minimum ventilation rates will not consider the varying demands and layout of the different types of dwellings e.g. small with high occupancy,” he says. 

Experience and best practice methodologies should be applied when specifying the ventilation rates of a dwelling – over and above the Building Regulation part F standards.

Similar issues can arise with over-ventilation, leading to overly dry internal conditions in winter. MVHR systems with an ERV (Energy Recovery Ventilator) core will help avoid over- dehumidification and should be considered for larger dwellings with low occupancy. 

If you are looking at ventilation options for your home, it could be worth taking a look at these natural ways to ventilate your home too.

Passivhaus ventilation needs some careful consideration early on in the design process if you want to ensure your new home is airtight, properly insulated and energy efficient. 

Passivhaus is a very high performance energy efficiency standard for new build properties and relies on a number of key details to maintain its high performance. Passivhaus is not a mandated standard but has all but become the go-to standard adopted by self builders and homebuilders looking for the highest aspirational performance standard in building. 

Passivhaus is fairly agnostic of what materials are used so long as they meet the high performance levels set by the Passivhaus Institute and are installed in a controlled and accountable manner by correctly trained experienced contractors. 

Why is Passivhaus ventilation important?

One of the most stringent Passivhaus performance details is the air tightness (draft-proofing). 

All energy used, and heat created, from living activities such as cooking, washing, lighting, electronic appliances and even our own body heat, is recycled to meet the heat loss of the property and lower the amount of primary heat that we need to supply through a central heating system. 

Clearly pumping heat out of the building in stale or polluted air is not efficient so the heat needs to be extracted from the stale air and retained in the home before it exits the building. The amount of air required for the healthy habitation of occupants in the building is carefully defined and regulated by both the Passivhaus standards and Building Regulations Part F. 

There are many details to consider but effectively you need a minimum continuous air flow of 13 litres per second extracted from the kitchen and 8 litres per second from wet rooms such as shower rooms and bathrooms. A WC needs an extract rated of at least 6 litres per second and all the extract air needs to be balanced with supply air to habitable rooms such as bedrooms and sitting areas. 

The home must also meet a minimum of 0.3 litres per second per square metre of floor area. This Building Regulations requirement can sometimes conflict with Passivhaus standards depending on the number of wet rooms and floor area of the home. 

What Passivhaus ventilation options are there?

Although not absolutely stipulated, it is widely accepted that a continuous Mechanical Ventilation Heat Recovery (MVHR) system is required to meet Passivhaus standards and is the approved ventilation strategy to meet the standard. 

An MVHR ventilation system continuously extracts air from wet room areas and delivers fresh air to living areas. As the stale air is extracted it passes through a heat exchanger where heat is transferred from the stale, outgoing air and delivered to the fresh incoming air. It is quite reasonable to expect around 90% of the heat to be recovered and retained in these types of homes. For a full Passivhaus certification the MVHR fan unit and ducting need to be approved by Passivhaus. If a non-approved MVHR system is used then penalty points are applied to the calculations in the Passivhaus design software. 

The MVHR system must also be installed by an experienced Passivhaus ventilation installer using approved installation methods with the full installation documented and photographed plus a full commissioning document produced with calibrated air flows to and from each room valve. 

How much does Passivhaus ventilation cost?

Due to the fact that Passivhaus MVHR systems are tested and approved by the Passivhaus Intitute there will inevitably be a premium on the cost of the machines and materials to account for the testing and approval costs. Expect to pay around £2500+ for a small home (c.120m2) fan unit, £3500+ for a medium home (c. 200m2) fan unit and around £4500+ for a larger home (c. 280m2) fan unit. 

One of the MVHR disadvantages to be aware of is cost and compared with a non-Passivhaus MVHR system the costs start at around half that price. The ductwork is not approved itself but must be installed in an approved manner so although the materials may be a similar cost for both systems the installation process will be more costly. The materials for the ducting start at around the same cost as the fan unit (but for better quality expect to pay more) with the installation also starting at around £3500 and more for larger properties. Double this cost for Passivhaus. 

Many installers will also not drill through structural elements so care planning and coordination is required.

As UK temperatures see year-on-year rises there are growing concerns over the lethal impact overheating is causing to homes.

2022 saw UK temperatures soar to above 40°C for the first time, while 2023 was the world’s hottest year on record, prompting a report from the Environmental Audit Committee (EAC) that has raised concerns over the UK’s lack of preparedness in its report on ‘Heat resilience and sustainable cooling’.

In this report it is claimed overheating is the “silent killer” and could claim up to 10,000 lives annually in the UK unless action is taken now. We look through how overheating can affect you and your health and the report's suggestions on how to prevent overheating in homes.

Over 4.6m homes experience overheating

Over 4.6 million English homes are affected by overheating during the summer months, according to the EAC.

Given that 80% of the homes expected to exist in 2050 are already constructed, there will be a significant need for widespread retrofitting to achieve net zero emissions and ensure thermal comfort.

EAC Chairman, Rt Hon Philip Dunne MP, said: “The world is heating up, and in the coming year we may exceed an increase of over 1.5°C above pre-industrial levels: breaking a key ambition of the Paris Agreement. The record temperatures we are seeing in UK summers, triggered by climate change, pose significant risks to health and wellbeing, and swift action must now be taken to adapt to the UK’s changing climate.

“Projections suggest that without action, there could be 10,000 UK heat-related deaths annually. High temperatures are costing the UK economy £60 billion a year: so measures to address the risks from overheating are simply a no-brainer."

Dr Radhika Khosla from the University of Oxford, who acted as Specialist Adviser for the EAC’s inquiry, said: “Sustainable cooling has rightly been pushed up the global agenda in recent years as temperatures rise around the world. But now that we recognise the problems from extreme heat, it is imperative we commit to the solutions. 

"Our hope is that this report helps the UK take action to meet its Global Cooling Pledge commitments and, most importantly, helps to save lives and protect people’s wellbeing while reducing emissions from cooling.”

How does overheating in homes claim lives?

Exposure to heat has various physiological effects on the human body, such as raising blood pressure and heart rate, which can affect multiple bodily systems including circulatory, nervous, respiratory, and renal systems. 

These effects increase the likelihood of illness or even death, including conditions like dehydration, heat exhaustion, and heatstroke.

In the UK, heat-related deaths surpassed 4,500 in 2022, with projections suggesting that this number could reach 10,000 annually if significant measures to adapt to a warming climate are not taken. Particularly vulnerable groups include individuals over the age of 65 and those with pre-existing health conditions.

Furthermore, hot weather also impacts mental health, with the risk of suicide being twice as high in the UK when temperatures reach 32°C compared to 22°C. 

Beyond physical and mental health risks, hot weather also has broader wellbeing effects on the population, such as sleep deprivation.

What solutions have been put forward for overheating?

The EAC emphasises the pressing need for accelerated heat adaptation measures in the UK.

They propose the development of a national retrofit programme, led by local authorities and supported by long-term funding, prioritising insulation, ventilation, and passive cooling over energy-intensive active cooling. 

Additionally, they suggest considering amendments to Building Regulations, particularly Building Regulations Part O, to promote the use of ceiling fans and facilitating access to low-cost finance for householders to to help keep houses cool in summer.

Nature-based solutions, such as parks, trees, and green infrastructure, are highlighted for their cooling effects and co-benefits like biodiversity and air quality improvement, especially in urban heat island areas like London. 

The EAC underscores the importance of these measures in mitigating the need for energy-intensive air conditioning, which risks exacerbating greenhouse gas emissions and further warming the planet. They stress the necessity of action to enhance the energy efficiency of air conditioners to avoid such a scenario.

Public information on overheating 'severely' lacking

The EAC claims that information concerning managing extreme heat is "severely" lacking and may not be effectively reaching vulnerable populations. 

In line with recommendations previously made by its predecessor Committee in the 2018 Heatwaves report, the EAC calls on the government to implement a public information initiative addressing the escalating risk of heatwaves and their considerable effects on human well-being and daily routines. 

They propose that the Met Office conduct a trial for naming heatwaves, akin to how storms are named, to increase public awareness of the health hazards involved. Additionally, they suggest the integration of humidity levels into weather forecasts and heat-health alerts to provide more comprehensive information to the public.

If you are looking to install a ventilation system in your project but aren't sure where to start then understanding what decentralised Mechanical Extract Ventilation (dMEV) is is a good place to start.

A dMEV system falls under the continuous mechanical extract ventilation systems proposed under the government's Building Regulations where homes can use either a central extract system, individual room extract fans or MVHR.

This system brings many advantages compared to its rivals and we'll run through the main benefits and how it differs from other ventilation systems.

How does a dMEV system work?

Decentralised Mechanical Extract Ventilation (dMEV) works by having multiple, smaller ventilation units distributed throughout a house.

Each dMEV unit typically has its air intake and exhaust components. These units can be wall-mounted, ceiling-mounted, or integrated into specific areas.

The unit draws in fresh outdoor air, filters it if necessary, and then circulates it into the designated space. Simultaneously, it extracts stale or polluted indoor air and expels it outside.

In a decentralised approach, each room or zone may have its ventilation unit, providing more localised control over air quality.

What is the difference between dMEV and MEV?

As mentioned dMEV systems consist of individual units placed in different rooms within a building, whereas centralised Mechanical Extract Ventilation (MEV) involves the installation of one central unit.

These systems, along with Mechanical Ventilation and Heat Recovery (MVHR), replaced Positive Input Ventilation (PIV) in the government's Building Regulations Part F as viable ventilation systems.

Although both systems work to remove stale air and provide fresh air, dMEV units work independently of one, but MEV units all work uniformly.

The choice between dMEV and MEV depends on factors such as the building's layout, specific ventilation requirements, and the desired level of control in different areas.

What are the benefits of dMEV?

Decentralised systems offer enhanced energy efficiency compared to centralised alternatives by enabling targeted ventilation. 

This means only the areas requiring ventilation receive service at any given time, reducing energy consumption, which can help save homeowners from energy price rises.

These systems are also designed with control mechanisms, allowing for localised management of ventilation parameters in various areas. This ensures flexibility tailored to specific requirements and preferences.

Many dMEV units are equipped with variable-speed fans and sensors that monitor indoor air quality and improve airtightness. This allows the system to dynamically adjust its operation based on the specific needs of the space, ensuring efficient and responsive ventilation.

Additionally, some dMEV units operate without requiring extensive ductwork, simplifying installation and lowering construction costs. However, it's worth noting that certain dMEV systems may still use short ducts for effective air distribution.

The dMEV system is also part of the government's Future Homes Standard proposals meaning it could be required in all new homes from 2025.

The government has published a consultation for the UK's Future Homes Standard that has set out proposals for the required standards for all new homes from 2025.

All options the consultation is looking at will see all new homes requiring air source heat pumps to be installed as well as other eco-friendly measures.

These options, it is hoped, will require all new homes to produce 75-80% less CO2 emissions than one built to current requirements, helping reduce the carbon emissions the UK produces.

All new homes will require air source heat pumps

The Future Homes Standard will require all new homes to install air source heat pumps in order to meet net zero goals.

Fossil fuel heating options such as oil and gas boilers will not be permitted whilst hybrid heat pumps and hydrogen boilers will also not be allowed as they were found to not meet the standards needed to deliver ‘zero-carbon ready’ homes.

Ground source heat pumps were not mentioned in the consultation and Homebuilding & Renovating have contacted the Department for Levelling Up, Housing and Communities to clarify whether they qualify but no response has yet been received.

Two options put forward for heating and hot water in new homes

As part of the government's latest consultation, two options were put forward for heating and hot water proposals in new homes from 2025.

The first option - referred to as "option 1" - would see all new homes requiring an air source heat pump, dMEV (decentralised Mechanical Extract Ventilation), a wastewater heat recovery system and high-efficiency solar PV panels covering 40% of the ground floor area of the home.

Meanwhile an alternative option would see all new homes only requiring an air source heat pump and natural ventilation with intermittent extractor fans.

The consultation will look at which of the two options should be implemented. The first option is already being touted as the most cost-effective option to maximise carbon savings as it is predicted to reduce heating and hot water bills by £910-£2,120 compared to Option 2's £210- £1,420 savings, but will also require higher upfront costs.

Baroness Penn, minister for housing and communities, said: “New homes and buildings must be fit for the future to help us reach net zero by 2050.

“Our energy-saving changes will cut bills for new homeowners and businesses, while also reducing carbon emissions by at least 75% for all new homes. This builds on our long-term plan for housing to deliver the high-quality, energy-efficient homes that local communities want and need.”

Mixed reaction from industry experts

Reaction to the news has garnered mixed opinions from industry experts with some claiming the plans will help expand the heat pump market whilst others claim the plans are cementing what is already being done by homebuilders. 

Ian Rippin, CEO of MCS (Microgeneration Certification Scheme), welcomed the announcement stating: "Mandating all space heating and hot water demand in new homes should be met through low-carbon sources will ensure the UK makes quicker progress towards decarbonising our housing stock. 

"It also gives homeowners assurance that they are making the right decision in installing a heat pump which is a proven technology for heating our homes.

"We are disappointed that no clear stance has been declared on mandating Solar PV for all new homes, but remain hopeful that the outcome of the consultation will conclude that solar is a must-have for new build homes, supporting homeowners by decreasing electricity bills, securing energy independence, and reducing their carbon impact."

Tamsin Lishman, CEO of Kensa the British Heat Pump Manufacturer, commented: “The publication of proposals requiring all new homes to be low-cost, low-carbon and energy efficient to run is a major step forward for the decarbonisation of homes and heat.

"This new standard will boost heat pump installations drastically, expanding the market from 50,000 to over 250,000 almost overnight, providing companies like Kensa with the confidence to go ahead and invest heavily in new manufacturing facilities and the continued development of our supply chains.

“It is particularly important that these proposals intend to make heat pumps and low-carbon heat networks the default options for heat in new homes, effectively banning new gas grid connections and so-called hydrogen-ready boilers from installation."

However, when asked about the lack of mention in the consultation about ground source heat pumps a spokesperson for Kensa stated: "Given the higher energy efficiency of GSHPs (ground source heat pumps) compared to ASHPs (air source heat pumps) there are no concerns that GSHPs won't meet the new building regulations.

"However, it is frustrating to see policymakers once again choosing one heat pump technology over another, explicitly naming ASHPs whilst making no mention of GSHPs.

"This has the potential to create a 'default' option for ASHPs, with many building developers not looking any further. We would like to see the wording of the final regulations remove this bias, setting notional standards simply for heat pumps, or for both technologies."

Simon McWhirter, Deputy Chief Executive at UKGBC, also criticised the proposals saying: "This can’t genuinely be described as a ‘future’ standard. Having already shattered industry confidence with repeated green rollbacks, the Government has opted for the least ambitious option that would deliver ‘future’ homes from 2025 at a lower standard than many homes already built today.

“While the Government is right, of course, to finally end the era of burning gas and oil in our new homes and buildings, fitting low-carbon heating sources such as heat pumps is already commonplace and the standard provides no improvement in energy efficiency."

Having one of the best dehumidifiers can offer a reliable solution to removing moisture from the air. From banishing damp, mould and condensation to helping to dry washing in the colder, wetter months, a dehumidifier is an essential appliance to have handy around the home. It’s one you’ll find helpful to have access to when drying out fresh plaster during a renovation, too (trust us – we’ve been there!)

Its versatility is unrivalled, and yet when it comes to buying a dehumidifier, the technical specifications can be a lot to get your head around. Much like the time when you’re looking at the best portable air conditioners; anything that manages the indoor air quality can be heavy talk.

As a team, we’ve spent months testing some of the latest and greatest dehumidifiers, evaluating factors like moisture removal, noise levels and running costs. With this information, we’ve created a list of the best eight dehumidifiers, with Meaco 20L Dehumidifier coming out on top.

The quick list

Not sure where to start in your search for the best dehumidifier? We've put together a handy overview of the options on this list, along with quick links that allow to you skip down the page to get a more detailed review.

• Back to the top ⤴

Best dehumidifier overall

The Meaco 20L Low Energy Dehumidifier/Air Purifier is designed to help control humidity levels in a house, reducing or even eliminating window condensation and, subsequently, minimising the risk of damp.

On test, we also found that it offers further benefits. It can help to dry laundry quicker and, thanks to its HEPA filter, can also purify the air – ideal for those with allergies and a great way to create a fresher-feeling indoor air environment in general.

This dehumidifier is perfect for those living in medium to large homes – spaces up to 64m² are well served by this particular model. It can also be used in unheated basements or cellars.

If you're looking for something ultra-quiet in the bedroom, we'd recommend the Meacodry Abc 12l Compressor Dehumidifier instead.

Read our full Meaco 20L Low Energy dehumidifier review for more details.

• Back to the top ⤴

Best mid-range dehumidifier

The ProBreeze 20L Premium Dehumidifier offers a powerful and user-friendly solution to combat damp and humidity in your home, especially if you live in a listed or poorly ventilated property.

We found this appliance easy to set up and its significant water extraction (up to 20L daily) noticeably improved the air quality in the home within a matter of days. Despite a somewhat noisy operation, benefits such as laundry mode, automated humidity detection, and an economical running cost make its mid-ranged price a worthwhile investment.

Another benefit of this model is its other operating modes including strong, natural, ventilation and continuous. In addition, this dehumidifier has a safety child lock to deactivate all buttons and a sleep mode that will turn all the lights off for undisturbed sleep.

However, if you want to use your dehumidifier in a cold room, such as a garage or basement, the EcoAir DD2 Simple Desiccant Dehumidifier or Meaco DD8L Pro Desiccant Dehumidifier will be a better choice.

Read our full ProBreeze 20L Dehumidifier review for more detail.

• Back to the top ⤴

Best compact dehumidifier

Despite being only 40cm in height, the MeacoDry Arete One 6L Compact dehumidifier packs a punch when it comes to performance. When Homebuilding’s Web Editor Amy Willis put it to the test, she was particularly impressed with how well it dried her laundry, how easily it could be moved from room to room, and how conveniently it could be placed on worktops out of the way of foot traffic.

It might have a smaller tank size than regular dehumidifiers, but you shouldn’t underestimate its power – Amy found it plenty big enough for her double-sized bedroom and helpful for tackling condensation, drying clothes and reducing humidity levels in her bathroom.

The model is quiet enough for an undisturbed night’s sleep (running at 32 dB) and comes with a free HEPA filter, allowing it to double up as an air purifier.

This dehumidifier also has excellent energy efficiency, running at 101 watts and costing around 3p per hour based on 26.35p/kWh energy pricing. When you compare it to the 12L model, which uses 151 watts, and the 25L model, which uses 67 watts, it puts into perspective how efficiently it runs considering it’s only a six-litre unit.

If you think you'll need a bigger tank size, the Meaco 20L Low Energy Dehumidifier and Air Purifier is a great alternative.

Read our full MeacoDry Arete One 6L Compact Dehumidifier review for more detail.

• Back to the top ⤴

Best dehumidifier for drying laundry

Although the De'Longhi DEX212F 12L Tasciugo AriaDry Dehumidifier is on the more expensive side, its sleek appearance is matched by its performance when it comes to drying laundry.

Fast, surprisingly quiet and efficient at drying clothes – leaving them feeling softer than when dried on a heated airer – our tester, Sarah Harley, found that a few downsides are that it's on the heavier side (10.3kg) and doesn't have a humidity level display like some of the other models.

If you're after something more lightweight, the MeacoDry Arete One 6L Compact Dehumidifier is an excellent alternative that can also be used for laundry but weighs just 7.9kg.

However, if you live in an apartment, meaning your drying options are limited to heated airers or tumble dryers, we feel that it is definitely a purchase worth considering.

Read our full DeLonghi DEX212F 12L Tasciugo AriaDry Dehumidifier review for more detail.

• Back to the top ⤴

Best dehumidifier for cold rooms

The EcoAir DD2 Simple Desiccant Dehumidifier is suited to colder spaces and has a powerful, yet relatively energy-efficient, wattage. With an automatic shut-off, anti-tilt safety function and a continuous drainage outlet, our tester Amy Willis believes that it's a good option if you are looking to leave it running in spaces such as garages.

Although it doesn't show humidity readings of the space you use it in, we found it to be, nonetheless, fast, efficient and light enough to move around if you're struggling with damp in a number of areas.

It's also fairly quiet to run, operating at 37-46dBa, making it suitable to use inside if your property struggles to get warm. Amy was also impressed by its "very powerful" laundry mode which extracted moisture from the air and was easy to select on the settings.

Read our full EcoAir DD2 Simple Desiccant Dehumidifier review for more detail.

• Back to the top ⤴

Best dehumidifier for bedrooms

Specifically chosen for testing in the bedroom due to its Quiet Mark rating and sleep function, we found this dehumidifier to be suitably quiet. While initially noisy when starting up, the fan quickly reduced to a low hum, making it easy to fall asleep while it works – even for light sleepers!

If you're looking for an affordable solution to window condensation in the bedroom, this could be a great option to consider. It also made the room feel warmer and the generous 12L tank capacityDe'Longhi DEX212F 12L Tasciugo AriaDry DehumidifierDe'Longhi DEX212F 12L Tasciugo AriaDry Dehumidifier meant it was still working when our tester, Sarah Harley, woke in the morning.

There are two options for reducing humidity: continuous extraction until you turn it off (which is recommended for drying laundry), or auto switch-off, which turns off once you've reached your desired humidity level and tests the air every 30 minutes.

Read our full MeacoDry ABC 12l Dehumidifier review for more detail.

• Back to the top ⤴

Best dehumidifier for garages

If you're looking for a solution for a cold, damp garage, the Meaco DD8L Pro Desiccant Dehumidifier comes highly recommended by Amy Willis. She put it to the test to see if it could prevent condensation, damp and mould from damaging her stored items in the garage, and was very impressed with the results.

One of her favourite things about this model – and a big reason why it's so good for garages – is that it comes with a wall mount to help keep it out of the way. This was particularly handy considering the dimensions were quite bulky, measuring 38cm x 36cm x 23cm.

It can extract up to eight litres of water per day and has a two-litre collection tank, as well as the option for continuous drainage. While it doesn't come with a hose, Amy says that you can fit a garden hose as an alternative.

The Meaco DD8L Pro can also be connected to your phone, allowing you to monitor the water tank and humidity levels remotely, which Amy found "useful but not essential".

It might be on the expensive side of dehumidifiers, but Amy says this model is "perfect for garages" and liked how you can tailor it to your space via the adjustable power settings. For something (slightly) more affordable, we also recommend the EcoAir DD2 Simple Desiccant Dehumidifier.

Read our full Meaco DD8L Pro Desiccant Dehumidifier review for more detail.

• Back to the top ⤴

Best smart dehumidifier

There’s a lot to like about the Duux Bora 20L Dehumidifier, which features an eight-litre daily extraction, a quick-drying laundry mode and a practical, portable design. But what makes this model stand out are its advanced smart features, which let you control it remotely from your phone or voice assistant.

When Homebuilding's news editor Joseph Mullane put it to the test, he connected the dehumidifier to the Duux app, which allowed him to set up to seven schedules and track his indoor air quality. He also liked how it integrates with Google Assistant and Amazon Alexa for easy, hands-free control.

Smart features aside, this dehumidifier has been a “game-changer” for reducing damp in Joseph’s home, thanks to its 20-litre extraction capacity and the hygrostat, which ensures humidity levels stay perfectly monitored.

He also found this dehumidifier fantastic for drying laundry and appreciated the continuous drainage hose for easy emptying and the roller wheels that make it easy to move from room to room.

The only drawback is that it can be slightly noisy when on the highest extraction rate, so if you plan on sleeping with a dehumidifier, the MeacoDry ABC 12L Compressor Dehumidifier is a better choice.

Read our full Duux Bora 20L Dehumidifier review for more detail.

• Back to the top ⤴

How we test the best dehumidifiers

To help you find the best dehumidifier, we researched the latest and top-rated products on the market, considering specs, price and customer reviews. After narrowing down the list, we tested the chosen products in our own home based on the following criteria:

• How easy they were to set up and use
• How effectively they extracted moisture in the air
• Whether they're worth the price tag
• How portable and user-friendly they were
• How noisy they were

Homebuilding & Renovating is not given any compensation for our reviews, but may be allowed to keep the products for long-term testing meaning we can test over a greater length of time, and update this review if required.

For more information, you can read our dedicated page on how we test products.

How to choose the best dehumidifier

Finding a dehumidifier that meets your needs and wants depends on the type of moisture that you’re trying to remove. A general rule of thumb is the larger the dehumidifier, the more powerful it’ll be.

According to Chris Michael, co-founder of Meaco, you'll need to consider the following factors:

1. Size of the property
You'll need to match the extraction rate to the size of the property:

• 6L: room only dehumidification 
• 10L: suitable for a small, two-bedroom flat
• 12L: recommended for a two-bedroom house
• 20L: suitable for a three-bedroom house
• 25L: recommended for properties with more than three bedrooms

2. Moisture levels
"If the property has high moisture levels due to damp issues, a high number of occupants, or regular indoor clothes drying, it’s best to choose the next size up. A more powerful model will remove moisture faster and more effectively."

3. Room temperature
"Compressor dehumidifiers perform best in heated homes, while desiccant dehumidifiers are better suited to cooler conditions, such as in a basement, conservatory or garage. The key temperature is 15°. Below this, go for desiccant, above 15°, go for compressor."

4. Energy efficiency
"Electricity consumption is an important consideration for an appliance that may run for much of the year. Models with a built-in humidistat are recommended, as they can be set to reach a target humidity level and then switch off automatically."

5. Noise levels
Be sure to check the decibel rating before investing in a dehumidifier. Models with Quiet Mark accreditation are a good choice for places like bedrooms.

6. Quality versus low-cost models
"While cheaper models may have a lower upfront cost, they are often less energy efficient and may not last as long. A higher-quality model can offer better long-term value through lower running costs and greater durability. Indicators of quality include longer warranty length, independent media reviews, and strong consumer ratings."

When won't a dehumidifier be suitable?

If your damp issue is the result of bad ventilation and lots of condensation, a dehumidifier can definitely help. That said, if damp is a persistent issue, caused by other factors concerning the structure of your home, a different and more involved solution is going to be required long term.

A dehumidifier will still help the situation but building work to fix the issue will be a better solution. Start by looking at the causes of mould in a house to help you figure out what could be the root of the problem.

If you're keen to do a little more research before making your purchase, read our guide to dehumidifier sizes and which dehumidifier is best for cold rooms.

Edited by Beth Murton.

More from Homebuilding & Renovating

Wondering if there are any MVHR disadvantages that could ruin your dreams of installing one of these systems in the hope enjoying their many benefits? Our guide is here to reveal the possible downsides so you can be sure this is a feature you want to go ahead with buying and fitting. 

Mechanical ventilation with heat recovery (MVHR) has so many benefits that it seems a shame to pick out their disadvantages, yet as these systems don't come cheap, it is crucial to be fully aware of their cons as well as the pros. 

Before getting into this, let's take a little look at exactly what MVHR is. 

"With a MVHR system, warm, stale air is passed through a heat exchanger in the air handling unit (usually positioned in an insulated loft, utility or within a dedicated plant room), and the heat extracted is then used to warm the incoming fresh air. (Fresh air is drawn in from outside and first filtered.)" explains expert in sustainable building methods and energy efficiency in residential homes Tim Pullen. "The pre-warmed, filtered fresh air is then delivered (moisture and cooking smell-free) into regular living areas through a ducting system with outlets in the ceilings of rooms."

MVHR disadvantages and advantages

It is really important to weigh up the pros and cons of MVHR systems before deciding to install one — after all, they are certainly not cheap.

"For a standard four bedroom house the system itself is likely to cost upwards of £3,000-£4,000," says Tim Pullen. "But the installation cost could easily double that, depending on the room layout and the difficulty of installing the ducting."

That said, there are also many advantages that, for most people, make these systems well worth the initial outlay. 

"I think MVHR is probably one of the best things you can put in your build or retrofit," says architect Paul Testa, Director of HEM Architects, who recently fitted one of these systems into his own home. "I would generally say that there are no real disadvantages — certainly that aren't outweighed by the advantages."

"The benefits of MVHR systems can also be numerous; from helping to improve air quality for those with allergies and respiratory diseases, to reducing issues such as condensation and mould, which blight many homes," says Tim.

In addition, they can be used to heat a house, eliminating the need for underfloor heating or radiators  — plus they result in similar temperatures throughout the house. 

We asked the experts what they think the main five disadvantages of MVHR are that homeowners should be aware of. 

1. High installation and running costs

One of the first questions most people ask when considering a MVHR is how much they cost — to buy, install and run.

"MVHR has many advantages but the disadvantages include that there is a fairly substantial installation cost and also a running cost," says renewables and ventilation installer David Hilton.  "Different systems have different running costs because if there is higher resistance then the fan works harder and uses more energy. You also need to change the filters periodically which can cost from around £15 for dust filters up to around £150 for some pollen or NoX filters."

"MVHR systems are an additional cost that most people don't factor into their initial budget for the self-build or retrofit," points out Paul Testa. "We'd typically allow £8-10K for a fully installed system, which isn't an insignificant number. However, the comfort and health benefits are amazing as is the elimination of condensation which can cause you costs in the long run."

2. Can be noisy 

Another leading concern for those thinking about including a MVHR system into their home design, keen to ensure good ventilation throughout their house, is noise, although most experts agree that most noise issues can be avoided through good design. 

"An MVHR system needs to be carefully designed. If poorly designed a system can be noisy and inefficient and not deliver the benefits that it should. This goes for poor commissioning as well," explains Paul Testa.

"Many systems may allow break-out noise," says David Hilton. "This is where the noise of the fan unit can travel down the ducts to the rooms. The next potential noise is 'cross talk'. This is where noises can travel from room to room through the ducts. TV noises from one bedroom, for instance, can then become disturbing in the next bedroom. There is also the noise of air movement. If the ceiling valves are closed up to balance a system the air can become noisy as it is restricted and vibration can also occur on the valve. 

"The final potential noise is resonance," continues David. "This is often referred to as the 'seashell effect.' The background noise in the room can ‘echo’ in the valve duct and seem like a noise. 

"However, all these noises can be mitigated with careful design, duct balancing and the addition of cross talk and breakout silencers."

3. Some maintenance required

As with so many fittings within the home, a MVHR system will require a little TLC from time to time if you want it to perform well and continue to do so over time. 

"MVHR systems are very low maintenance — but not maintenance free," says Paul Testa. "You should be changing filters every 3-6 months, depending on the conditions outside your home, and the unit should, like your boiler, be serviced regularly."

4. Can make it tricky to have an open fire or log burner

If you are keen to include an open fire or even a log burning stove within your home then there are a couple of things you need to know about how they work alongside MVHR.

As a rule, if your stove is less than 5kW, there will not usually be a requirement for ventilation. However, for stoves or open fires with an output of more than 5kW, you will need 550mm2 of permanent ventilation for every additional kilowatt. 

Now, if you are going to all the trouble to create an airtight home and installing an expensive MVHR system, to then create what is effectively a hole in the wall or up through the roof is rather counterproductive  — plus MVHR system can affect the performance of a stove.

"You can’t have open fires or woodburners with internal air supply unless you have a dedicated external or direct air supply," says Tim Pullen.

"MVHR systems, and indeed other forms of mechanical air extraction, will alter room air pressure which in turn could adversely affect the performance of the stove's flue or chimney system," say the experts at The Stove Yard. "To maintain safe air quality in your home the proposed stove should have a direct external air supply (DEAS) and importantly, should have an effective door-seal to make it virtually room-sealed. This means that the stove's safe operation will not be affected by potential changes to the room air pressure caused by mechanical ventilation. When the door is closed none of the stove's combustion air can be taken from the room and conversely none of the combustion gases produced can escape."

5. Ducting takes up extra space

Anyone installing a MVHR system needs to ensure they are planning early on in the design stages to ensure the whole thing works well and is worth the cost. One particular issue that needs addressing is the extra space requirements for the ducting required.

"The ducts take up space so need to be planned in or they will need additional boxing which will be intrusive," explains David Hilton. 

"The ducting will tend to be 100mm to 150mm in diameter, depending on the size of the house. The warmed incoming air also needs to be insulated, to make sure the heat gets to the right place, which could increase the diameter to 250mm," says Tim Pullen. "Clearly ducting can’t be put just anywhere and needs to be properly designed in."

"Any ducting that passes through ‘cold’ spaces (like a cold roof loft) will need to be insulated to optimise the efficiency of the system," adds David Hilton.

Mould in houses is a very real issue, yet it is a problem that often gets ignored or covered up. This means that inappropriate building work that may have caused the problem is never addressed, and so the problem continues.

Doctors have long been aware of the links between mould growth and ill health, particularly amongst the young, the elderly and people with respiratory conditions such as asthma. The case of two-year old toddler Awaab Ishak, who died in December 2020 from a severe respiratory condition caused by prolonged exposure to mould at his home in Rochdale, reminds us of just how seriously we should be taking mould growth in our homes. Yet there’s comparatively little awareness of what actually causes the problem.

While understanding the best ways of mould removal is a good start, it is even better to understand and fix the root of the problem. So it may come as a surprise to learn that renovated properties can be especially prone to the sort of conditions where occupants suffer from respiratory illnesses, allergies and fungal infections. 

In this guide, we cover everything you need to know about mould, from what causes it in the first place to the different types of mould you need to be on the lookout for.

Types of mould explained

Mould is a living organism that proliferates in the indoor environment as long as conditions are favourable. The word ‘mould’ is a collective term for spore-producing hyphomycetes fungi and there are actually many different types of mould to be aware of. 

When allowed to propagate, some moulds can produce mycotoxins, so inhaling excessive quantities of airborne particles may lead to allergic reactions with symptoms such as wheezing and itchy eyes or skin caused by irritation of mucous membranes in the eyes and respiratory tract. 

There are several different types of mould but the ones most commonly found in our homes are the black and green varieties, both of which can be harmful to health. 

Green mould typically has a fluffy appearance and is often found growing on damp walls, inside cupboards and on carpets. 

Black mould is more common and a particularly toxic micro fungus variety, stachybotrys chartarum, is often detected on cellulose-rich building materials in damp or water-damaged buildings.

The main causes of mould

As well as potentially endangering occupants’ health, mould growth can obviously have a detrimental effect on a property’s visual appeal and hence its market value. Estate agents know only too well that if potential buyers are accosted by rampant mould the ‘yuk factor’ will very likely be reflected in the price they’re prepared to offer.

In my experience as a chartered surveyor, poor indoor air quality and mould staining are often associated with properties that have been partially refurbished to reduce air leakage and heat loss. The problem with improved air tightness is that unless the works are carried out as part of a carefully coordinated programme there’s a danger that it can lead to poor air quality with stale air not being replaced at a sufficient rate due to a lack of ventilation. Problems tend to be more pronounced in older properties with solid masonry walls and blocked up fireplaces. 

A classic example might be a self-contained flat in a cheaply built block with newly installed double-glazed windows. A combination of airtight windows with little or no air extraction from kitchens and bathrooms causes water vapour to become trapped, resulting in high humidity and condensation forming on uninsulated external walls. 

Activities that generate large volumes of water vapour, such as cooking with gas, tend to exacerbate the problem. So the most obvious potential trouble spots in the home tend to be poorly ventilated bathrooms and kitchens.

Keeping relatively humidity under control

Moulds are a natural part of our ecosystem. Microscopic spores invisible to the naked eye are present in the air we breathe interspersed with dust particles. Problems only start to develop where the spores land on surfaces prone to excessive moisture, which in some homes may be related to modern occupancy lifestyles that generate large quantities of water vapour. 

Any building, old or new, can potentially be at risk, but mould is more likely to flourish with high levels of indoor humidity typically caused by condensation, water leaks or penetrating damp. It can be helpful to look at how to solve condensation.

In severely affected properties there’s normally an unmistakable damp, mouldy odour accompanied by outbreaks of black speckled mould on cold spots, such as window and door reveals. 

However, not all outbreaks of mould in the home are readily visible to the naked eye or detectable by the average human nose. So to determine whether a property is at risk you need to gauge how moist the indoor air is. 

Relative Humidity (RH) measures how close the air in a building is to being saturated, telling you in percentage terms how much water vapour is in the air compared to the maximum possible at that temperature. The ‘dew point’ is the temperature at which the air reaches saturation point at 100% RH. Warmer air can hold more water vapour, so as the temperature drops the RH will increase until it gets to 100%. At this point it’s completely saturated and cannot hold any more water vapour so it offloads it in the form of condensation (assuming the air pressure remains constant). 

To measure relative humidity a device known as a hygrometer is traditionally used but (inevitably) you can now download hygrometer apps to your smartphone. To avoid the risk of harmful moulds developing, the general consensus is that relative humidity should be maintained below 80% and ideally no more than 65%. 

One thing to bear in mind is that measurements taken in the atmosphere of a room tend to be lower than ones taken next to the surface of main walls. So a relatively safe reading in your living space could be misleading if the equivalent figure in the ‘danger zone’ next to the wall is redlining above 80%, which could be enough to promote mould growth even before condensation occurs.

Best mould solutions

The first step to eradicate the risk of mould infestation in the home is to reduce moisture levels sufficiently to prevent future spore growth. A decent dehumidifier can be a useful piece of kit for this purpose as a temporary measure until permanent improvements have been carried out to ensure the building functions satisfactorily in future.

Where you’ve got visible mould staining, the contamination can normally be removed from hard surfaces by thoroughly cleaning with a weak bleach solution, specialist mould remover or steriliser spray (remembering to wear appropriate PPE). This is important because old mould growth, even when inactive and powdery, can still be potentially detrimental to health if spores are inhaled. Any severely contaminated porous materials like damp plasterboard or mouldy carpets will need to be cut out and replaced. Once the building fabric has been allowed to dry out, relative humidity levels should if possible be maintained below 65%.

As noted earlier, inadequate levels of ventilation are a major part of the problem, especially when combined with high levels of indoor humidity. So it’s advisable to install efficient modern extract fans in kitchens as well as bathroom extractor fans in bathrooms, cloakrooms and utility rooms.

Humidistat fans are particularly useful because they operate automatically when humidity levels become dangerously high. Functioning trickle vents in windows have a role to play to help disperse humid air, and reinstating original ventilation paths from fireplaces etc can also improve air quality.

Where it’s practical to install a mechanical ventilation system this can be an ideal solution for maintaining consistent humidity levels in the home. To finish the job, cold surfaces around the envelope of the building should be insulated, particularly walls, window reveals and lofts. 

The final remedy to deter mould growth is to review any lifestyle changes that could be made to help reduce indoor moisture such as cutting back where possible on boiling food and indoor clothes drying.

When the colder months of the year close in condensation can quickly build up in a loft space, leading to excessive and unwanted moisture. This can saturate the timbers and eventually comprise the structure of the loft space.

But it's not just the damage it can do to the fabric of your home. Condensation will lead to damp issues, which can lead to mould, which will raise the risks to you. So the right type of ventilation is crucial for the well being of you and your home.

Here the pros give you the lowdown on what types of loft insulation is available and how to be compliant with building regulations.

How loft ventilation stops condensation

Rob Stone, founder of loft boarding specialists, Instaloft, says: “Lofts are typically cold spaces, with the house being typically warmer. When this warm air from the house meets the cold of the loft, condensation will occur if there is no adequate ventilation, and quickly build up.

“Over time, condensation can seep into the wood of roof trusses, causing the wood to become wet, and potentially weakening the roof structure of a home.”

Rob adds: “The temperature differential between different parts of the house, combined with a lack of ventilation in the loft creates the perfect damp conditions for mould to thrive and build up.”

Samuel Hitch, MD at Buy Insulation Online Ltd adds, "If that warmer, moisture laden air becomes trapped in the loft it will begin to condensate on the cold surfaces like rafters, tiles and bitumen based felt and start to drip down on to any contents or the ceilings below.

This is most pronounced in winter when external surfaces are much colder than the ambient air inside the loft. Mould will inevitably begin to form on timbers and contents as it is happiest in humid dark climates from 60% humidity and up.

The old bitumen felt that is non breathable exacerbates the problem as it effectively traps humidity within the loft."

Home heating and insulation expert and LoftZone CEO Dave Raval warns against overfilling your loft with storage.

He said: “If your loft is overcrowded, this can also block ventilation. The loft constantly needs breathing space so the air can flow, allowing your home to be warm in the winter and cooler in the summer.”

Try these for your loft space

Types of loft ventilation

Adam Blair, the founder of roofing contractor company ADM Roofing Ltd, outlines the main types of roof ventilation available:

1. Running vents These stretch across the soffit boards that span the underside of the roof. For the sake of ease, this type of ventilation is typically installed alongside the roof as a whole, meaning this type of ventilation would be ideal if you are looking to completely overhaul your loft. Otherwise, this time consuming process may not be a practical cost-effective solution for you.

2. Circular soffit vents These are small plastic vents carved into softboard panels, which are there to keep the loft insulated. Unlike running vents, this type of ventilation is much easier to implement and can be lined up with any additional work you are looking to do to your loft.

3. Ventilation slates These can provide extra ventilation support to any house that may be lacking efficient built-in ventilation. These slates can be placed all around the roof, mixed in with standard slates and tiles so as to not compromise the neat uniform look of the roofing work.

Loft ventilation and building regulations

Gary Jarman, from Building Shop, shares what you need to consider, "To ensure that your loft ventilation is compliant with building regulations, it's important to consider what type of loft your property has. In other words, if your space is inhabited and used as a living area, or uninhabited and used for storage."

Beyond these considerations he starts with what you need for an inhibited loft, "As inhabited lofts have insulation next to the surface of the roof, they require a minimum ventilation pathway of 25mm around between the insulation and the surface of the roof. This also requires a continuous opening at the eaves of the roof, this is in line with the British Standard BS 5250."

He adds, "In addition, a 5,000 mm²/m opening across the length of the ridge of a roof is required to remove moisture from this space. Furthermore, if you have a bathroom in your loft space then an extractor fan is required by building regulations."

There are different ways to help with loft ventilation such as insulating a loft hatch. But another way is to take on a loft conversion. Check out types of loft conversion and bedroom loft conversion ideas for insight and inspiration.

The National Grid could offer free energy-efficiency upgrades to homeowners close to proposed new pylons.

The pylons are vital for the UK’s net-zero ambitions but will likely be vehemently opposed by homeowners with properties in their shadow.

These properties may be offered free home insulation, ground and air source heat pumps, and other energy-efficiency installations to win over householders.

Homes that ‘host the infrastructure’ should have a reduced ‘cost of energy’

The pylons are needed to link renewable energy projects such as wind farms to the existing power network, but are expected to impact tens of thousands of properties.

Ben Wilson, National Grid’s chief strategy officer, told the Telegraph the company wants people living alongside pylons and cabling to benefit from the infrastructure with measures like enhanced insulation.

He said: “I do think if you’re hosting the infrastructure, you should get a benefit in terms of your cost of energy, maybe help with energy insulation or helping to electrify your home in terms of heat.” 

Mr Wilson suggested National Grid could also set up training academies to boost employment in the affected areas.

And to prevent electricity shortage, National Grid said the amount of generating capacity connected to the grid would need to treble by 2030.

Proposals put forward after protests to pylons increase

The number of homes and properties affected by cables and pylons will increase sharply over the next decade as a result. Protests are expected to rise sharply too, Mr Wilson conceded.

He said the benefits of the new infrastructure should also be more targeted on the actual households affected.

Mr Wilson, speaking at the Labour party conference in Liverpool, admits local objection to the plans is likely to be severe.

This is why the energy-efficiency upgrades, which could include smart heating tech and solar panels, are being targeted directly to the impacted households.

Wilson said: “We can do a lot to mitigate the impact but in the end you do have to have some new infrastructure.” 

Last week around 200 people gathered to protest the Norwich to Tilbury project to build more than 100 miles of 50-metre high pylons across East Anglia.

Campaigners argue that offshore options would be cheaper and simpler, but claim that the National Grid has not properly considered them.

Who will qualify for these free upgrades?

As the proposal to help homes with energy-efficient technology is just a suggestion, it is not yet known which properties would be affected.

However, considering the new infrastructure would require five times more overhead lines as have been built in the last 30 years, it is likely that a huge amount of homes will be affected.

Last month Octopus Energy launched a new smart heating system that aims to "pave the way for heat pumps for everyone" in Britain.

The energy supplier's "Cosy Octopus" offer includes several components, such as an air source heat pump, a home controls system and room sensors, as well a customised smart tariff. 

Ever noticed white patches of a powder-like substance on your walls, furniture, or fixtures? It could be mildew, but what is mildew and what (if anything) do you need to do about it?

Ensuring home ventilation is adequate is of vital importance to tackling mildew outbreaks in your home.

Here Malik Ahmed, home improvement expert and director of Bolt World, outlines what mildew is, what causes it, and how to prevent it.

What is mildew?

Mildew is a type of fungus that commonly appears as white or grey powdery patches on surfaces in damp or humid environments.

When it comes to mildew vs mould, both are fungi that can grow in homes, but they have distinct differences. Mildew typically appears as powdery, white or grey patches on surfaces and thrives in moist environments like bathrooms. While it can cause minor health issues, mould, with its various colours and fuzzy or slimy texture, is more diverse and can be significantly more hazardous to health, often requiring professional removal and remediation.

What causes mildew in a home?

Mildew in a home is typically caused by a combination of moisture and organic materials. While poor ventilation can contribute to the development of mildew, it is not the sole cause. Here are some common factors that can lead to mildew growth:

• High humidity: Mildew thrives in environments with high humidity levels. Areas like bathrooms, kitchens, and basements are particularly susceptible if they are not adequately ventilated or have poor moisture control.
• Dampness: Any surface or material that remains consistently damp or wet can promote mildew growth. This can occur due to leaks, condensation, or prolonged exposure to moisture.
• Organic materials: Mildew feeds on organic materials like wood, paper, fabrics, and even dust. If these materials are exposed to moisture, mildew can develop.
• Lack of ventilation: Poor ventilation can exacerbate mildew issues by trapping moisture indoors and causing damp. Proper ventilation helps maintain a balanced indoor humidity level and reduces the likelihood of mildew growth.
• Insufficient cleaning and maintenance: Neglecting regular cleaning and maintenance of areas prone to moisture buildup can create an environment conducive to mildew growth.

How to get rid of mildew

Homeowners can get rid of mildew by following a few key steps:

• Identify the source of moisture: Before addressing the mildew itself, it's crucial to identify and eliminate the source of moisture that is promoting mildew growth. This might involve fixing leaks, improving ventilation, or addressing humidity issues.
• Protect yourself: When dealing with mildew, it's a good practice to wear protective gear, including gloves and a mask, to avoid inhaling mildew spores and to prevent skin contact.
• Remove the mildew: Depending on the surface and severity of the infestation, you can often remove mildew from walls and hard surfaces using a scrubbing brush or a heavy-duty cloth along with a general household cleaning solution. Make sure you are wearing gloves to protect your hands. 
• Prevent future growth: To prevent mildew from returning, address the underlying moisture issue. Improve natural ventilation, fix leaks, and maintain a dry environment. Consider using dehumidifiers in areas prone to high humidity.
• Regular maintenance: Regularly inspect areas where mildew is likely to occur, such as bathrooms and basements, and promptly address any signs of moisture or mildew growth. Improving things such as bathroom ventilation along with consistent cleaning and maintenance can help prevent mildew from returning.

Remember that mildew can have health implications, so it's essential to handle it with care and take appropriate precautions. If you have health concerns or are dealing with a severe infestation, it's advisable to consult with professionals for remediation.

Improving ventilation to prevent mildew

Improving ventilation is an effective long-term solution to preventing mildew in your home, especially in areas where moisture tends to accumulate, like bathrooms, kitchens, and basements. Proper ventilation helps maintain a balanced indoor humidity level and promotes air circulation, which can significantly reduce the risk of mildew growth. Here's why it's a valuable long-term strategy:

Reduced humidity: Adequate ventilation helps reduce indoor humidity levels by expelling moist air and bringing in drier outside air. Lower humidity inhibits mildew growth since mildew thrives in high-humidity environments.

Improved air circulation: Good airflow helps prevent moisture from becoming stagnant in specific areas, which is crucial in areas where condensation can occur. Stagnant air can create pockets of high humidity, making it more conducive to mildew growth.

Faster drying: Ventilation facilitates the drying of wet surfaces and materials more quickly, which is essential for preventing mildew. For example, after taking a shower, using an extractor fan or opening a window can help moisture evaporate faster.

Prevents stale air: Proper ventilation also helps maintain fresh indoor air quality. Stale, damp air not only promotes mildew but can also create an uncomfortable and unpleasant living environment.

FAQs

While improving ventilation is essential for preventing mildew, it is often part of a broader strategy that includes moisture control, regular cleaning, and maintenance. Combining these measures can help keep your home mildew-free in the long term.

A Lincolnshire self build on the site of an old quarry has gone onto the market for £1million.

The 'Glasshouse' is a four-bedroom home in Upgate, Louth, which uses a Mechanical Ventilation and Heat Recovery system (MVHR) as well as other eco-friendly features to provide an example of a contemporary self-build home.

The home was built by housing developer Alex Holdsworth, 40 – who has lived at the property for the last two years and who described the house as "like being at Center Parcs". Take a tour through the house and its features with us.

A 'perfect contemporary family' home

The Glasshouse combines construction materials like Siberian larch timber cladding, buff brickwork, and floor-to-ceiling windows and doors. 

It uses features such as a cantilevered first floor with outdoor seating and entertainment space, as well as a second floor with 360-degree glass walls and a balcony, from which the home gets its name.

Alex Holdsworth stated: "The setting and views are stunning, you can see so much and look out onto everything in the area.

"Louth is a very nice place with good schools and plenty to do, it's a very good town and the surrounding beauty makes it perfect for a contemporary family."

MVHR and solar panels help the home gain a 'B' EPC rating

An 'Airflow' MVHR system provides fresh air throughout the house by using bathroom and kitchen extractors.

It also recovers heat from the home to warm incoming air, contributing to the home's 'B' EPC rating, along with the assistance of photovoltaic solar panels and underfloor heating reducing energy bills.

White theme running throughout the home's features

The home's four bedrooms includes two en suites, with the master bedroom also including a dressing room.

The kitchen-diner includes a white marble kitchen island and leads onto the balcony area. The bathroom continues the white marble theme with white marbled walls and flooring.

Block-paved drive and triple garage with inbuilt gym

The property features gardens that blend into the hillside of the former quarry, offering an example of how to build on a sloping site.

Large trees at the back overhang the rear of the house, whilst a wide, block-paved driveway leads to the triple garage, which includes a gym, and the drive is bordered by raised gardens, enclosed with gabion walls.

The home has been listed at a guide price of £1million by estate agents Robert Bell & Company.

The Home Upgrade Grant can help homeowners make energy-efficient upgrades to their home with the help of government funding.

The scheme provides local councils with funding to help existing off-the-grid housing stocks, that cannot afford the improvements themselves, reduce their carbon footprints.

Here we guide you through what the funding can be used for, help see if you're eligible, and how you can apply to your local council to help gain funding if you're looking at renovating a house.

What is the Home Upgrade Grant for?

This grant is for non-mains gas heating systems and aims to provide energy-efficiency upgrades and low-carbon heating solutions for low-income households living in the least energy-efficient homes.

The improvements that can be made include improving your home's ventilation and insulation, installing secondary glazing and MVHR, and much more.

This is in addition to other government schemes such as the Boiler Upgrade Scheme, which provides £7,500 towards the installation of a heat pump.

How does the scheme work?

Local authorities are allocated a set amount of funding for the Home Upgrade Grant to provide improvements to housing in their areas.

Homeowners can apply to their council to receive the funding to make improvements to their homes to increase their energy efficiency and save on house renovation costs.

In order to find your local council the Gov.uk has a portal to each council's website so you can easily get in contact with the correct authority.

Who can apply for the Home Upgrade Grant?

In order to qualify for the scheme, homes must meet a certain set criteria or else their applications will most likely not be considered.

This criteria includes:

• The home must be off the gas grid
• The gross household income must be below £31,000 per year
• The home must have an Energy Performance Certificate (EPC) between D and G
• The home must be in one of the local authority areas listed (find your council tool)

If you meet these criteria, you can contact your local council to acquire funding.

A list of the eligible local councils can be found on the Gov.uk website.

How long will the Home Upgrade Grant run for?

Up to £630 million in grant funding has been allocated to support eligible local authorities in their implementation of the Home Upgrade Grant spanning from April 2023 to March 2025. 

This funding will be spread out to qualifying local councils annually with set amounts given each year during 2023-2024 and 2024-2025.

Once this funding runs out for these years there is no guarantee more will be available in the future, so eligible homeowners should apply as soon as possible.

Damp can cause huge problems and needs to be displaced from kitchens and bathrooms – but how exactly how does an extractor fan work?

Mould in rooms with high levels of moisture looks awful, can produce a nasty smell, damage your windows and fixtures, potentially spread across paint, wallpaper, and plaster, and cause respiratory health problems.

That's why it is important to make sure you have the best bathroom extractor fans installed in the appropriate location in your home.  But how to assess which extractor fan is the most suitable for your home? Here we look at how they work so you have a better understanding when it comes to making your choice.

How does an extractor fan work?

An extractor fan, also known as an axial-flow fan, operates by creating a flow of air. It consists of a rotating arrangement of vanes or blades, which act on the air.

The rotating assembly of blades and hub is known as an impeller. The fan is usually contained within a housing or case, which can direct the airflow and increase safety by preventing objects from contacting the fan blades.

Most fans are powered by electric motors. When the fan operates, it forces air to move parallel to the shaft about which the blades rotate. This movement of air helps in removing moisture, odours, and other contaminants from a specific area.

Do extractor fans need to vent outside?

Yes, it's crucial for extractor fans, especially those used in domestic settings like bathrooms and kitchens, to vent outside.

Venting outside ensures that the moisture, odours, and other contaminants are effectively expelled from the room or building, preventing issues like mould growth and maintaining good indoor air quality.

For this reason, extractor fans should either be fitted to exterior walls or have ducting to an exterior wall vent.

Do extractor fans use a lot of electricity?

The electricity consumption of an extractor fan depends on its size, power rating, and usage duration. Generally, domestic extractor fans used in bathrooms and kitchens have a relatively low power rating and do not consume a significant amount of electricity when used for typical durations.

However, larger industrial extractor fans or those used continuously for extended periods will consume more electricity.

“It's always a good idea to check the power rating of a specific fan model to get a better understanding of its electricity consumption,” Property expert Paul Gibbens, of housebuyers4u says.

Are energy-efficient models less powerful?

Not necessarily. Energy efficiency in extractor fans (or any appliance) refers to the ability to perform a task using less energy.

Paul says an energy-efficient extractor fan like this one for sale on Amazon can be just as powerful as a less efficient one; the difference is that it achieves the same airflow or extraction rate while consuming less electricity.

“Advances in motor technology, blade design, and other components have allowed manufacturers to produce powerful fans that are also energy-efficient,” he says.

How often should you clean a bathroom extractor fan?

It's recommended to clean a bathroom extractor fan at least once every 3-6 months. However, the frequency can vary based on usage and the level of dust and humidity in your bathroom. If you notice a decrease in the fan's efficiency or increased noise levels, it might be time for a cleaning.

Property expert Paul Gibbens, of housebuyers4u, has put together a list of reasons it is important to know how to clean a bathroom extractor fan.

• Improved Efficiency: Over time, dust and grime can accumulate on the fan blades and motor, reducing its efficiency. Cleaning ensures the fan operates at its optimal performance.
• Extended Lifespan: Regular maintenance and cleaning can extend the lifespan of the fan by preventing wear and tear caused by accumulated debris.
• Better Air Quality: Cleaning the fan ensures that it effectively removes moisture and contaminants, maintaining good air quality in the room.
• Reduced Noise: Dust and debris can cause the fan to make more noise. Cleaning can help reduce these noise levels.
• Safety: A clean fan is less likely to become a fire hazard due to accumulated dust or grease.

Set against a backdrop of drystone walls, earthen banks, and ancient ring forts, this eco-friendly home by Studio Anois cleverly blends into its rural surroundings and has been designed to keep its occupants cool even in the warmest of summers.

From the outside, Diamor House is a picture of simplicity. Its square form and unassuming exterior is clad in natural slate - a choice that helps regulate temperatures while maintaining a connection to the local environment. But stepping through its doors reveals a clean and contemporary interior, with a striking light well at its heart, and a unique approach to home ventilation.

Keep reading to discover how this one-of-a-kind home is a sustainable triumph, from its prefabricated timber frame to its innovative heating and cooling systems.  

The house is designed around a light well 

The house has been thoughtfully designed around a central light well, which not only illuminates the interior from above but also enables natural ventilation. When the light well window is open it creates a cooling effect by drawing in fresh air and allowing it to circulate throughout the home.

Elsewhere, the house has been meticulously designed to incorporate varying floor levels and ceiling heights. Not only do these serve to separate functional zones for eating, cooking, and relaxation, but these spaces also play a crucial role in regulating temperatures, as they help optimise airflow by creating natural 'cooling' zones. 

There's a strong link between inside and out

The building is flooded with natural light thanks to several floor-to-ceiling windows. Each window has been carefully positioned to frame views of the surrounding countryside and also contribute to the home's overall 'cooling' strategy. By aligning windows to capture prevailing breezes and directing airflow, they are able to harness the power of nature to naturally bring the house's temperature down.

The connection between the indoors and outdoors is further enhanced by a thoughtful garden design, which brings greenery right up to the house. A patio area, designed by Siobhan Keogh, perfectly complements the building's design and provides an inviting space for the homeowners to relax and unwind outside. 

Ductless MVHR and sustainable credentials 

Diamor House has been designed with sustainability at its core. Everything from the choice of materials to the insulation methods, and energy systems all contribute to reducing the ecological footprint of the property. 

The structure itself was prefabricated off site using panels that are made up of a twin stud timber frame, filled with cellulose insulation. Meanwhile, the foundations and floor slab are designed to omit cold bridges, utilising an insulated passive concrete raft slab.

The home is heated by a ground source heat pump and triple glazed windows ensure that the house stays warm during the winter months. An innovative ductless MVHR system has been installed, and the light well window can open up to provide natural ventilation year-round. 

Minimalist design with varying floor heights

The sleek and minimalist interiors are particularly impressive considering Diamor House was a self-build project. The property owners have successfully designed a home that flows seamlessly from one space to the next. The clean white colour palette serves to enhance the breathtaking views of the Irish countryside, turning each window into a living painting, and inviting its occupants to relax and enjoy the beauty of nature just beyond the glass. 

A couple seeking to sell their home were left shocked when they received a 'D' EPC rating, despite the home receiving a 'C' rating when it was built in 1994.

The couple claim the home has high insulation levels with a U-value (the rate at which homes lose heat) of just 0.1W/m2K and includes an air source heat pump.

An EPC assessor produced a Reduced Data Standard Assessment Procedure (RdSAP) that "assumptions" had to be made which meant they did not inspect the property, but made their judgements on what they could see, which has called into question the efficacy of RdSAP EPC ratings.

Here we explain what is an EPC rating, what the difference is between SAP and RdSAP's and the potential issues you can face with RdSAP's.

What is an EPC rating?

An EPC rating, also known as an Energy Performance Certificate rating, helps homeowners find out their homes energy rating and its energy efficiency.

The rating is based on an assessment of various factors such as the building's insulation, heating system, ventilation, and energy usage.

The EPC rating is represented on a scale from A to G, with A being the most energy-efficient and G being the least efficient. The ratings provide an indication of the energy consumption and carbon dioxide emissions of a building.

EPC ratings are typically required when a property is sold, rented out, or constructed.

The ratings can also highlight potential areas for improvement, such as upgrading insulation or replacing inefficient heating systems, which can lead to energy savings and lower utility bills.

How does a RdSAP rating differ from a SAP?

SAP calculations (Standard Assessment Procedure) are the methodology used by the government to assess and compare the energy and environmental performance of new builds, conversions and extensions.

The RdSAP is a simplified version of SAP used to assess energy performance of existing dwellings. 

An RdSAP assessment will use a set of assumptions about the dwelling based on conventions and requirements at the time it was constructed. RdSAP's are required every 10 years to reassess home's energy performances.

RdSAP 2012 is the current version used to produce assess energy performance in existing dwellings.

Couple received rating lower than when it was built

The couple were seeking to sell their home and so sought an up-to-date EPC assessment through Elmhurst Energy, who run the accreditation scheme.

The EPC assessor produced a RdSAP EPC which rated the property as 63, Band D; despite the EPC rating being 78, Band C, when the home was built.

This, the couple claim, is backed by full detailed SAP calculations, air tests, Building Control, and photographs. 

The couple also claim the property has high levels of insulation including a super-insulated floor (Springvale Platinum Beamshield Plus with a U value of 0.10 W/m2K). The RdSAP EPC makes no rating on this even though there is a space for this.

 The house has also been fitted with additional features since it was built, such as:

• An air source heat pump (Nibe Fighter F2015 8.5 kW) as well as underfloor heating
• Heat and vent recovery system - Villavent VR400 DCV/B with DC motor
• Beam and polystyrene block floor - Cube6  with a 0.1 W/m2K
• Green roof aids reduction in solar gain in summer
• Garage fully insulated to same standard as house (except floor), with an insulated door
• Rainwater recycling system with underground tank
• Inner walls hard plastered to assist in thermal mass heat stabilisation

'RdSAP EPC is not worth the paper it is printed on'

Julian Moss, one of the homeowners, claims the "RdSAP EPC is not worth the paper it is printed on".

She stated: "We still have all evidences for the original EPC (including the original EPC) such as invoices, photographs, air tests, full SAP calcs etc. The 'assumed' energy consumption figure is almost double the real world figure. The property has been well maintained, and no alterations to the building fabric carried out since the 'as built' tests, checks and calculations were completed."

She wrote to Elmhurst Energy claiming: "RdSAPs appear to be pseudo-science and have no real validity regarding energy performance; you should not be permitted to issue certificates based on these using the nomenclature EPC.

"An RdSAP EPC is an utter misnomer, it is not an Energy Performance Certificate by any stretch of the imagination; a real SAP uses real science and calculations, not assumptions, to allow for the issuing of a real EPC. 

"Whilst changes may occur to a property over time, the original EPC clearly is far more meaningful and accurate than the suggested RdSAP EPC replacement. It seems that the RDSAP EPC is a misleading waste of time and can only take room measurements and 'assumptions' into consideration, not evidence."

She went on to say: "It is time RdSAP EPCs are cancelled".

EPC rating 'in line' with current policy

Despite these claims Elmhurst Energy have backed their rating Band D for the home after writing to the couple explaining their decision.

Tony Robinson, the Existing Dwellings Technical Consultant at Elmhurst Energy, wrote to Julian to justify the decision, claiming: "Variations in score (EPC rating) are not uncommon although I accept that the variation here is larger than we often see."

He explained: "This assessment requires a site inspection and the assessor records the physical characteristics of the property, walls heating etc. It is a non invasive survey and because the assessor does not have full access to the all structural elements (the full makeup of the wall for example) they cannot they make the detailed calculations used in SAP, hence reduced data.

"The U values in this case are normally derived from the properties characterises and are based on calculations of made by the Building Research Establishment (BRE) of typical properties of the type recorded. These typical value may well be less that the U values recorded in the SAP EPC.

"Regrettably therefore I have to advise that the EPC [the assessor] is proposing does seem to be broadly in line with the current methodology and whilst this will develop over time we are unfortunately where we are at the present time."

RdSAP's called 'crazy' by expert

The claims by this couple have been backed by experts who have called into question the accuracy of RdSAP's, and EPC's in general.

David Hilton, Homebuilding & Renovating's heating expert commented on this couple's RdSAP assessed EPC rating, claiming: "It is crazy that the efficiency of a premium home is solely down to what you can see."

He claims this "makes a mockery of trying to build better as any resale will need an EPC which will be only as good as building regulations, if that. Apparently, a heat pump is regarded as direct electric because there is no heat pump on the software."

A report earlier this year also showed EPC ratings "to be staggeringly inaccurate" after reviewing 17,000 homes energy usage showing their energy usage is 91% lower than what their EPC's claim they use.

Homebuilding's other energy expert, Tim Pullen, also stated, "the methodology currently used to produce them (EPC's) does not instil any confidence in their accuracy or efficacy” and suggested "the software used to generate EPCs are ridiculous".

Julian Moss has requested an "accurate EPC" is done on the couple's home and has requested Grant Shapps, Secretary of State for Energy Security and Net Zero, to "immediately suspend RdSAP EPCs and replace them in the near future with a more scientific based alternative".

The government is currently working on an RdSAP update (RdSAP 10.2), which is expected to be published soon.

MVHR and underfloor heating can work hand in hand to provide you with a living environment that's both cosy and cost-effective. 

Though sometimes costly, this combination of cutting-edge technologies can offer a great return on investment — something highly-desirable for most homeowners. But you may be wondering if this dynamic duo is right for you. 

In this article, energy expert David Hilton explains why installing both Mechanical Ventilation with Heat Recovery (MVHR) and underfloor heating could be a savvy move for your self-build project.  

Why is MVHR and underfloor heating a good mix?

MVHR is designed to extract humid and stale air from wet rooms, such as bathrooms and kitchens, while simultaneously bringing in fresh air from outside. This air exchange occurs through a heat exchanger, preheating the fresh air before it enters habitable rooms. 

Though MVHR and underfloor heating are not physically interconnected, they are frequently combined during the design and construction phase thanks to their synergistic qualities. The steady heat output of underfloor heating aligns well with the consistent ventilation provided by MVHR, ensuring a comfortable indoor environment.

What are the benefits of MVHR and UFH?

Opting for MVHR in conjunction with underfloor heating offers several advantages over traditional heating systems, such as radiators. Unlike radiators, underfloor heating distributes warmth evenly across the floor, eliminating the need for bulky radiators that can occupy valuable wall space. 

The MVHR system's consistent ventilation lowers peak heat loads, reducing energy consumption and providing optimal comfort. This combination is particularly effective in well-insulated, energy-efficient homes.

How to install MVHR with underfloor heating?

Underfloor heating together with the ducting for a MVHR system can impact floor build up, especially in multi-story homes. So proper planning is necessary to accommodate the ductwork and pipework, ensuring they fit without compromising other design elements. 

Sometimes the MVHR ductwork and underfloor pipework will need to be in the same place, especially in intermediate floor spaces such as between the ground and first floor. This can be a design challenge as well as an installation challenge. Whichever system gets installed first, the other one may need to be threaded through it without causing any damage. Any service risers will also need to be sized correctly to ensure that all the ductwork and pipework will not only physically fit but that it can also be practically installed. It is very important that if the two services are both in the same space that the installers are aware that the other will also need space so that everything fits. 

There is no hard and fast rule as to who should go first but usually I would say the bigger items (except for some drains) should really go in first. That said, if the underfloor heating is to be installed on the underside of the first floor floorboards then in that case underfloor heating is the natural priority. 

In my experience the easiest solution where projects have MVHR and underfloor heating in the same floorspace is to allow the ducts of the MVHR to run between the joists and then the UFH is fitted in overlay boards that are placed above the deck board. There will be more buildup on the floor level but if this is designed and specified early then the stairs and door frames can also be designed accordingly. 

Can MVHR and UFH be installed on a DIY basis?

For the avid (and competent) DIY enthusiast both MVHR and underfloor heating represent the opportunity to potentially fit the ductwork and pipework yourself. 

With good design and decent support the process of installing the ducts and pipework is not actually that difficult but can take time. You also have the opportunity to fit things at exactly the right time and not wait for the installation trades to be available. Do however make sure that you know what you are taking on, have the right tools and materials, and also allow enough time as these things do tend to take a bit longer than you may anticipate.

If you would like to read more about MVHR system costs and installation, you can read about my own experience in my article: I installed MVHR and it has completely stopped condensation in my home.

There are hundreds of types of mould that grow in homes, and it can cause significant problems if left to fester. As well as being unsightly, it can produce a nasty smell, damage your fixtures, and potentially spread into paint, wallpaper, cloth and plaster.

Spores and mycotoxins can also cause health problems, triggering allergic, respiratory, immune, and inflammatory reactions, as well as long-term conditions such as hypersensitivity pneumonitis This is why mould removal is so important.

Below, we've explained 10 types of mould you need to know about, with expert advice on how to kill it. However, if there is a large amount or it's a particularly dangerous strain, it's always best to leave the removal to professionals.

1. Stachybotrys chartarum (toxic black mould)

There are several types of black mould, and identifying the different variations can be difficult without professional expertise and proper testing. Stachybotrys chartarum appears dark greenish-black, and often has a wet, shiny, or slimy appearance – rather than the dry, more velvety look of other types of mould.

Where it can be found: It thrives on damp walls, particularly behind or on wallpaper and fibreboard, and in cool, damp conditions.

Health issues: Most black moulds come from the same strain as green mould and aren’t too much of a concern – but one type is toxic. Stachybotrys chartarum produces mycotoxins that can be harmful if inhaled or ingested over an extended period.

How to kill it: Michael Zohouri, founder of Pyramid Eco, says, "In my experience, you can’t just spray and wipe. You need to cut out contaminated materials, bag them, and make sure the source of damp is fixed. This is one where I’d almost always recommend professional remediation."

2. Cladosporium (non-toxic black mould)

Cladosporium isn’t considered toxic and is generally not dangerous to healthy individuals, but it can cause allergic reactions or worsen asthma symptoms.

Where it can be found: It typically appears black or greenish-brown, with a texture that ranges from powdery to suede-like. Cladosporium can grow on various materials, including fabrics, carpets, wood, and damp walls, but it’s commonly found in areas with high humidity and poor ventilation, like bathrooms, kitchens, and basements in humid months of the year.

Health issues: It can trigger allergic reactions and respiratory issues in some people.

How to kill it: Michael says, "The good news is it usually stays on the surface. A mould remover spray or white vinegar works well. Improve airflow and it tends not to come back."

3. Trichoderma (green mould)

Trichoderma often appears as fuzzy patches that start out white or yellow and turn green-grey as they mature.

Where it can be found: It’s most commonly found in forests and soil, but it can also thrive on paper, wood, and textiles in damp, high-humidity areas. You can use a hygrometer to check if your humidity levels are normal.

Health issues: Some species of Trichoderma can produce mycotoxins, but they are generally considered less harmful to human health than other mould species.

How to kill it: Michael says, "If you catch it early, a good scrub and drying out the area can work. If it’s established, materials may need to be replaced.”

4. Alternaria (brown/green mould)

Another variety of green mould, Alternaria is often dark green or brown, with a velvet-like texture.

Where it can be found: It’s found in damp places like under leaky sinks, bathrooms, and kitchens, and is most common between July and September, but it does grow all year.

Health issues: It spreads quickly, and although most species are not harmful, the spores can cause allergies and asthma-like symptoms. It can also cause respiratory issues and skin irritation in some pets and people.

How to kill it: Michael says, "Use a mould spray and monitor the area – and again, check for the cause of the damp."

5. Mucor (white and fluffy)

Mucor is a fast-growing fungus and will eventually turn a dark grey colour if left long enough. The white 'fluff' is known as Sporangiospores, which are designed to catch the wind to spread its spores far and wide, according to Mold Busters.

Where it can be found: This is often found growing on overripe fruit as well as on anything that is dead or decaying, often in the soil and on plants, but potentially in the house if you discover a dead mouse! Mucor also loves condensation so it can be found on a constantly wet windowsill as well as in any consistently damp areas.

Health issues: Mucor is not considered toxic to healthy humans. That said, it is classed as an allergenic type of mould/fungi, so those with compromised immune systems could develop an infection or respiratory issues if the spores are inhaled, according to a study published by Science Direct.

How to kill it: Michael says, "It’s important to use a HEPA vacuum to safely remove loose spores before wiping down. If the conditions are right, it can cover large areas in days, so act quickly."

6. Penicillium

Where it can be found: Penicillium is velvet-like in texture and appears in a blue-green shade. This type can usually be found as mould on wallpaper, carpets, mattresses and HVAC ducts.

Health issues: It can cause allergy symptoms, which typically occur after allergic individuals inhale mould spores, and spreads quite quickly, so it’s better if you can identify infestations early.

How to kill it: Michael says, "On hard surfaces, a vinegar solution or mould spray works. On anything porous, it’s often safer to discard and replace."

7. Ulocladium

Where it can be found: This type of mould is most commonly found in bathrooms, kitchens and basements that have had water damage or that have been exposed to moisture for long periods of time. It typically appears black in colour and appears in clumps.

Health issues: Ulocladium fungi mostly cause opportunistic infections in immunocompromised individuals.

How to kill it: Michael says, "A good biocide can remove it, but I’d always investigate for leaks or long-term condensation behind it."

8. Fusarium

Where it can be found: Fusarium is often found growing on food but can also appear in wallpaper, carpets, and water-damaged materials. It spreads very quickly and comes in red, white, or pink shades.

Health issues: Fusarium species cause a broad spectrum of infections in humans.

How to kill it: Michael says, "Treatment involves cleaning, drying out cold surfaces using the best dehumidifier, and improving insulation."

9. Chaetomium

Where it can be found: Chaetomium usually appears white in colour but will darken as it matures to a grey, brown, or black shade. It can easily be identified by its musty odour. This type of mould is common on wooden surfaces, on wallpaper, under wet carpets, and in water-damaged areas of your property.

Health issues: It can easily lead to severe allergic reactions and respiratory infections in immune compromised people.

How to kill it: Chaetomium is often mistaken for black mould, so it’s best to leave removals to the professionals.

10. Acremonium

Where it can be found: Acremonium typically appears in small colonies of grey, pink, white, or orange moist mould patches that turn powdery. This type of mould is found most commonly in drains, drip pans, humidifiers, HVAC cooling coils, and around leaky windows.

Health issues: It can cause human superficial infections including mycetoma, onychomycosis and keratitis.

How to kill it: It often appears with black mould and will require removal by a professional.

Michael Zohouri concludes, "The key thing for all types of mould is to fix the moisture problem that caused it in the first place. You need to treat the causes and remove the mould entirely to stop it from coming back."

If you're struggling to get rid of mould on your skirting boards or want to learn how to remove mould from walls, read our expert guides next.

Exhaust air heat pumps (EAHP), also known as heat pump ventilation or micro heat pumps, use energy from ventilated air to heat your home and/or water. This ingenious technology reuses energy from 'waste air' in your home and can reduce your energy bills in the process. 

With air source heat pumps firmly on the radar of many homeowners looking for more efficient heating systems, you may be wondering how you can incorporate this technology into your own home?

Thankfully, eco energy expert David Hilton is on hand to provide all the lowdown on EAHPs. In this article, he covers everything from how they work to installation, system costs and what options are available for your home. 

How does an exhaust air source heat pump work?

Exhaust air heat pumps are designed to use the air in the home as its heat source. It works by extracting heat from stale, humid air before exhausting it outside the property. 

They are small heat pumps, usually using around 600 Watts of power and producing around 2kW of heat. This heat can then be transferred in two ways:

Air-to-water setup: The heat is conveyed to water, either directly or indirectly, by integrating the heat pump with a hot water cylinder. This arrangement is known as an air-to-water system.

Air-to-air setup: Alternatively, the heat can be transferred to the air for use in conjunction with a Mechanical Ventilation Heat Recovery (MVHR) system, known as an air-to-air system.

Air-to-water systems

Because exhaust air heat pumps only use around 600 watts of power to produce around 2kW of heat, they do not heat up water in the cylinder very fast, which means you may need a slightly larger store capacity, depending on the water usage patterns in your home. That said, the low energy use does make them particularly useful in maximising the generation from renewable electric generators such as photovoltaic solar PV panels.

Very often an electric vehicle charger will only turn on if there is a spare 1.4kW so this system is also useful to use the lower generation when there is not enough for the car. You will however need it to be wired into an energy diverter system. 

Micro heat pumps are not a new technology as there have been small heat pumps built into hot water cylinders for many years, especially in countries where natural gas is not available for heating. Things have moved on a bit with the introduction of newer refrigerants and the development of better compressors and smart control systems.

An integrated system

The prevailing design of an exhaust air heat pump involves integrating a small heat pump into the upper part of a hot water cylinder. These integrated systems are commonly available in 200 or 300-litre volumes. This setup features two duct connections on the cylinder's top surface—one for drawing air in and the other for expelling air out.

When the water in the cylinder requires reheating, the heat pump engages by pulling air through a heat exchanger (often from the bathroom or kitchen). This air's heat is then transferred to the water storage. These types of exhaust air units have been around for a number of years and the quality of the products can differ greatly from manufacturer to manufacturer. 

Air-to-water EAHPs are predominantly used for hot water only and you will need an alternative solution for space heating. There are however some occasions where this unit can also be used for space heating if the heating demand is exceptionally low.

Costs

Expect to pay around £1,200 for a simple version of a EAHP product, with costs rising to around £2,000 for newer units and even as much as around £3,000 or £4,000 for units with more connectivity and control.

Retrofit options

There are also ‘retrofit’ versions of these exhaust air heat pumps that do not have a hot water cylinder attached. The fan unit instead goes in the loft, or near the cylinder, and you run ducts from the bathroom and other wet rooms, as well as the route to outside for the stale, cold air, and then plumb it to the cylinder, most often in a parallel system. Before buying one of these systems it is worth checking that it is compatible with your existing cylinder and plumbing arrangement with a heating engineer. 

These retrofit exhaust air heat pumps can cost as little as around £900 with more complex units going upwards of £4,000. Make sure you also factor in any remedial plumbing and electrical works required to connect it to existing cylinders and controls. 

Air-to-air EAHP systems

Micro heat pumps are also available as air-to-air systems rather than the air-to-water options. The air-to-air units are often made to work with a MVHR unit and they are also commonly only able to do cooling. The cooling box is normally installed on top of the main MVHR fan unit and effectively makes it a taller box. The unit extracts heat from the fresh air going to the rooms in the home and dumps the heat in the stale expelled air. Some of these units can also be reversed so that heating and cooling options can be used but they are not easily retrofitted and should be planned into the ductwork design when the system is initially designed. 

Exhaust air heat pumps with MVHR integration

There are also micro heat pumps that have been factory built into MVHR systems, often referred to as heat pump ventilation, and can do both heating and cooling. The heating and cooling function is done while the air is being delivered to the home so that indoor temperatures can be maintained. These systems are most effective in very low-energy homes like Passivhaus builds. For other properties, heat delivery might not suffice, requiring increased air speed, potentially leading to noise concerns.

There is an argument that if you fit one of these systems you may not need a wet heating system and therefore the cost is offset by not needing the alternative heat generator and wet emitter system such as underfloor heating or radiators. Just make sure that the design calculations have been done with your expectations in mind and that you fully understand the type of heating system that you are investing in. 

Many MVHR installers are now fully versed with cooling options and you will need the MVHR installer to insulate the ducts. Duct insulation is not something that you want to add after the MVHR system has been installed.

The cost of add-on cooling units for MVHR systems varies between manufacturers, ranging from £3,000 to £5,000. Additionally, duct insulation costs between £6 to £35 per meter, depending on quality and diameter, alongside installation expenses.

A powered cooler box is usually a cooler box with a fan that blows air over a metal surface and evaporative cooling results. I tested this on a three day trip to a camping festival. We are a family of four, in a tent in a field with no electric hook up. And it was during a heat wave with temperatures hitting 38.5C in parts of the UK.

Here, we take a look at how this piece of kit could come in useful for those living on site when self building or renovating — or even those who find themselves without a fridge when remodelling. Of course, it could also come in useful in many other circumstances. 

What is the Makita DCW180Z?

The Makita DCW180Z (which you can buy here at B&Q or here with a battery operated Makita kettle too) is better described as a fridge. There is a compressor and a refrigerant circuit (using low Global Warming Potential (GWP) refrigerant R1234. 

The cooler box can be powered with Makita 18V LXT batteries, which are also used in the vast range of Makita LXT tools. There are two slots to plug the batteries in but it only needs one to work (two batteries simply keeps the cooler box running longer), or alternatively it has a 240V mains power adapter or an adaptor for use on a car 12v power supply. 

The cooler box is truly portable as it has a shoulder strap so you can carry it hanging from your shoulder and there are also two wheels and a handle so you can drag it on its wheels a bit like a travel suitcase.

What is included with the Makita DCW180Z cooler and warmer box?

This product is comprised of:

• Compressor type cooler and warmer box
• 2 x 18v LXT Makita 18v batteries or plug in mains adaptor or plug in 12v car charger
• 20 litre capacity
• LED temperature display
• USB charging point 
• Built in bottle opener
• Built in wheels
• Side handles and shoulder strap for portability

What is the Makita DCW180Z like to use?

The Makita DCW180Z has around 75% of its total volume as usable cooling space. The rest of the volume houses the compressor and the store for the batteries. The cooling space is accessed via a top lid with a separate top lid to access the battery compartment. 

When packing things into the cooler section it is not a huge space so some careful planning is required. Twelve small bottles will fit into the box but 12 standard 500ml drinks cans will not. Shorter cans can be stacked two high. By putting the cans in first, including tall containers such as milk, and then packing thinner things like cheese and bacon in between the cans the space is better utilised. 

There is a separate compartment on the top of the box for concealed batteries and the USB charger. There is space for two Makita LXT 18v batteries to be connected. I have 12 Makita 5Ah batteries that I use for work and I made sure that all were charged up before leaving. 

On the top of the box is a digital display that tells you the temperature in the box and also the charge capacity of both batteries. The box seems to use one battery at a time. During the day the box will use around two batteries (it was over 30 degrees celcius in the tent) but at night it was a lot cooler and there was no change to the charge indicator. 

Over the three days I used six Makita 5Ah LXT batteries for the fridge. You can hear the unit running but it is not disturbingly loud. It does not run all the time as the box seems robustly built and is well insulated. The box has a handy USB charging port in the battery compartment so you can charge your phone and it also has a convenient bottle opener attached to the outside box.

Does the Makita DCW180Z keep food and drinks cold?

The temperature of the cooler was kept at 3 to 4 degrees over the whole three days and it really was that temperature. During the heat wave it was an absolute blessing. As we replenished stocks of drinks they would also be brought down to the required temperature just as they would in a normal fridge. 

Any of the other campers that saw this definitely had ‘fridge envy’ that weekend and I am not sure if I could ever go camping again without it. 

Who would benefit from buying a Makita DCW180Z?

The Makita DCW180Z is also a great thing to take with you in the car on a day out or if you are doing the shopping on a hot day. Remember that it can be powered by the 12v power socket in the car. Pop the milk and perishables in the box and you have no need to race home to stop them melting or going off. 

During your deep renovation or self build project this would especially handy to keep the milk fresh and we all know how important a cup of tea is on site.

Can the Makita DCW180Z keep food and drinks warm?

Yes, the Makita DCW180Z can also warm. If you need to keep the burgers warm straight off the bbq or keep the food warm at Christmas, then this could be just the ticket. 

It is also great additional fridge space when you have guests or want a cooler close at hand outside in the garden. Clearly it cannot be used for cooling and heating at the same time so the biggest problem with this product may be the discussion at Christmas whether it should be used to keep the turkey warm or the beverages cold.

Looking at what is the best fan for cooling is a good starting point when considering how to cool yourself down when the summer heat cranks up.

Fans, unlike home air conditioning, can be inexpensive to both buy and run, compact, lightweight, and offer a sense of immediate coolness. From budget buys to sleek bladeless technology, a fan can be a simple solution to stop your home from feeling stuffy and uncomfortable during the hot summer months.  

In this article, we'll take a look at several different types of fans, discover how they keep us cool, and share our thoughts on the best cooling fans to buy. 

What is the best fan for cooling? 

The best fan for cooling is all about finding a fan with an airflow greater than 150m3 per hour (there are 1,000 litres to 1m3). 

A cooling fan like the Dyson TP7A Autoreact bladeless tower fan would easily fulfill this criteria with an airflow of 1,332m2 per hour, keeping you fabulously cool in summer as well as having other features like purified air and looking super sleek. But at £399.99 a unit, this fan would be at the higher end of many people's budget scale, which might not suit everybody's "best fan for cooling" requirements. 

Meanwhile, this far more basic electriQ high velocity desk fan is only £24.99 with an airflow of 2,000m3 per hour but no air purifying or super sleek look and needs to sit on a desk or table to push air around at the right height. 

That's where answering the question of the best fan for cooling gets more complicated as different types of fan have different unique features and strengths, which suit different people's priorities.

What are the main types of cooling fan?

There are four main types of cooling fan to choose from when looking at which fan might be the best choice for you. These are:

Box fans: These fans are compact and budget-friendly. They are best for small spaces but can still pack a punch in terms of air circulation.

Standing fans: Also known as pedestal fans, these direct airflow towards specific areas. They're arguably the least aesthetically pleasing type of fan, but they circulate air efficiently.  This electriQhigh velocity pedestal fan provides an airflow of 6,000m3 per hour.

Tower fans: These fans have a slimline design and oscillate to cool larger spaces. They often feature multiple speed settings, as well as convenient timers. The Honeywell QuietSet Tower Fan is a popular tower fan, as it has 5 distinct speed settings and 75° oscillation, which allows it to cool a whole room quickly and quietly.  

Bladeless fans: The best known bladeless fans are those made by Dyson. Fans such as the Dyson TP00 Pure Cool provide a consistent stream of air circulation, are safe to use, and can even purify the air in your home. All of Dyson's purifying fans use Air Multiplier™ technology with 350-degree oscillation, allowing them to project up to 290 litres of air per second.

Do cooling fans actually cool the air?

Unlike air conditioning units, fans don't actually lower the temperature of the air. Instead, they create a wind-chill effect. By circulating the air in a room, they evaporate sweat from your skin which makes you feel cooler. 

If you're trying to figure out how to keep a house cool in summer, then it pays to ensure you are using your fan in the most effective way. We suggest directing them upwards, so no large items of furniture are blocking the flow of air. Similarly, you could try positioning a bowl of ice water in front of a fan, so the frosty water particles will be circulated throughout the room. 

When Evan Stevens, Head of Environmental Care at Dyson, shared his tips for keeping your house cool, he suggested running a cooling fan during the night, as well as opening your windows to allow cooler air to enter the house and circulate. 

How to choose the perfect cooling fan

Fans come in all shapes and sizes, with price tags ranging from budget-friendly to £399 plus. So, how do you find your perfect match? Here's a simple guide:

Cooling power: If you want something that can really bring down the heat, look for a fan with an airflow greater than 150m3 per hour.

Noise: We all want a fan that does its job without making a racket. The quietest fans can operate at a whisper-quiet 20dB, rising to around 70dB at full speed. Bladeless fans also tend to be the quietest option.

Aesthetic: Many fans aren't exactly easy on the eye. If design matters to you, you might want to splurge a little on a sleek Dyson or a slimline tower fan, like the John Lewis Tower Fan, 42 inch.

Energy efficiency: Powerful fans don't necessarily consume more energy. In fact, larger fans can often cool a room effectively at lower speeds compared to smaller fans running at higher speeds. Turning off fans when they're not in use can significantly reduce energy consumption. For more information on energy efficiency, you may want to read our handy guide: how much does it cost to run a fan?

Our pick of the best cooling fans 

While many families switch on their air conditioning units at night to help them sleep — apparently, doing so might be having the opposite effect.

Sleep experts are suggesting that running your AC at night could in fact be making you feel worse the next day. This is due to it potentially disturbing your sleep in a number of different ways. And that's before your next energy bill comes in...

But ditching the air conditioning unit all together isn't a good idea either, with reports suggesting that the ideal temperature for a bedroom is between 16 and 18°C to get a good night’s sleep as well as the functionality of air conditioning units being improved when a room's temperature isn't allowed to get too hot.

"Cooling is often a gradual process that happens in cycles and therefore the air conditioning may need to be switched on before the room heats up too much," Homebuilding & Renovating's energy efficiency expert David Hilton explains.

We look at why choosing run your best portable air conditioners during the daytime instead of at night is probably a sensible compromise, either that or investing in a more suitable unit for your needs.

Your AC unit can circulate dust and pollen 

While having your windows open will allow pollen and dust into your bedroom, having your home air conditioning unit running at night while you sleep, can circulate it around the room.

"Hay fever and allergens are typically airborne, so fans and ACs can spread them around your room and onto furniture and bedding, resulting in sneezing, coughing, and watery eyes," Ashley Hainsworth from Bed Kingdom explains. "Relaxed breathing is essential to a night of good sleep, so when our allergies are triggered by polluted air in our bedrooms, it can lead to poor-quality sleep that leaves you tired in the morning."

The solution is simple, run your air conditioning unit in your bedroom during the daytime when you aren't using it, and switch it off at night. And on low pollen-count nights, open up the windows to allow cooler air in. 

"Sleep masks can also help keep pollen out of your eyes when you sleep, as well as regularly changing sheets and washing pets to keep them free of irritants," Ashley Hainsworth at Bed Kingdom adds.

If you really suffer from allergies at night, you could also look at investing in an air purifier to help you sleep. The Honeywell HPA830 Designer Tower Air Purifier is Quiet Mark certified making it a decent choice for overnight.

Noise from your AC unit can disturb your sleep

The Sleep Charity suggests most people generally need a quiet bedroom to sleep well, with noise tending to be most disruptive in the lighter stages of sleep but most damaging when it wakes us up from our deepest sleep. 

That means a loud fan or air conditioning unit blasting away all night is not going to help give you a restful night, potentially leaving you feeling groggy and tired the next day — the opposite of what is likely to have been intended by keeping the unit running.

That said, if you desperately do want to keep your AC unit running at night, there are air conditioning units that have a night mode. These are far quieter when in this mode, to help avoid any sleep disturbances. 

The DeLonghi Pinguino portable air conditioning unit is on the pricier end of the scale but claims to have a noise level of between 47 and 51 decibels. Meanwhile the wall-mounted LG split air conditioning unit with heat pump claims to produce a rather impressive minimum of 19 decibels.

Getting too cold will ruin natural sleep rhythms

Waking up shivering because your AC unit is pumping out too much cold air is not only unpleasant, it can really interfere with your sleeping patterns. 

Alvin Pullins, a home improvement and maintenance specialist, tells Homes & Gardens: "Maintaining a cool and comfortable bedroom environment is crucial for a good night's sleep. However, shallow temperatures, especially during sleep, can interfere with sleep quality and overall restfulness."

Not only that but more warmth in the bedroom will help sooth and relax and tense muscles overnight.

Running your AC unit at night will be expensive 

The type of air conditioning you use is a factor in working out exactly how much your air conditioning will cost to run at night, but as a general guide David Hilton says it can be around 68p per hour for AC units that use 2kWH of electricity. This is based on an average electricity price of 34p/kWh.

Hilton explains: "Air conditioning costs depend on the output of the unit that you install. The air conditioning system uses electricity to run a refrigerant system that creates the cooling. The cooling power is more than the electric consumption so a 6kW air conditioning system may use only around 2kWh of electricity."

That means, if you having your AC unit running for nine hours each night — it'll be costing you £6.12 a day, £42.84 a week and £189.12 a month. Given how much cooler it is at night compared to the day, this might be a good place to save money on your energy bill. It's also worth pointing out that you can get portable air conditioning units that are more energy efficient, such as the ElectriQ range on Appliances Direct. Theirmore powerful model pumps out 12,000BTUs with a cooling power of 3.5kWh, which should only use around 1.2kWh of electricity — plus it has an inbuilt fan and dehumidifier.

More tips to keep cool at night

Keeping blinds closed during the day and opening windows at night is the best thing to do when considering how to cool down a room.

"Heat can transfer from the sun into a room. During the hottest parts of the day, consider keeping blinds and curtains closed to block any unwanted heat transferring," says Ashley Hainsworth from Bed Kingdom. "This is especially important if any windows are facing the sun. If your blinds are dark in colour, consider switching them for a light cream or white to stop them from absorbing the heat."

On the flip side, opening blinds in the early morning or late evening can help cool the room before you go to sleep as this is when it is cooler outside.

Meanwhile, Maddy from Mattress Online recommends opening up your loft hatch to allow the heat inside the attic to escape. At Homebuilding & Renovating we agree with the theory of letting heat escape out of the loft to keep bedrooms cooler but, really the way to be properly doing this is through appropriate ventilation in the loft space rather than having to open up the loft hatch.

Other tips on how to prevent overheating in homes include switching your bed sheets to natural materials such as 100% cotton, bamboo or linen, wearing loose cotton pyjamas, sleeping downstairs, keeping space between you and your partner, and making pets sleep in their own beds rather than snuggle their heat into yours.

A pioneering technology called AeroBarrier is transforming the construction industry with its approach to improving airtightness in buildings. 

After emerging in the United States, AeroBarrier has launched in the UK to block unwanted airflow, aiming to significantly enhance energy efficiency and indoor comfort.

This technology claims to allow those building a house to choose their desired air tightness and create homes that meet ventilation building regulations, while also reducing energy bills for homeowners. 

We take a look at how AeroBarrier technology works, how it alters airflow and whether it might be a worthwhile option for your project.

What is AeroBarrier?

AeroBarrier is a new technology designed to improve airtightness. It has already been rolled out to great success in the USA, Canada and the UAE, and has just become available in the UK too.

The way AeroBarrier works is essentially by sealing air leaks in buildings using a special mist that contains tiny particles engineered to form an airtight barrier. This mist is released into the building interior and dispersed throughout the space. As it travels, it automatically seeks out and seals any gaps or leaks in the building envelope. The particles in the mist are propelled by air pressure, and as they accumulate, they form a continuous and complete seal, effectively blocking any unwanted airflow.

And it's creators are so confident of AeroBarrier's effectiveness that they'll guarantee it to a specific level of airtightness — either the UK building standard of 8 m3/hr.m2 or to Passivhaus levels of 0.6m3/hm3.

Why is this airflow control important in a home?

Airflow can be categorised into two main types: intentional and unintentional airflow.

1) Intentional airflow is deliberately designed and controlled through ventilation systems. This includes natural ventilation with the supply of fresh air from outside and the removal of stale or polluted air from indoors. Intentional airflow is often achieved through mechanisms such as windows, doors, vents, and mechanical ventilation systems like fans or air conditioners or MVHR systems.

2) Unintentional airflow, on the other hand, refers to the movement of air through unintended paths, such as gaps, cracks, or leaks in the building envelope. These unintended pathways can occur around windows, doors, electrical outlets, plumbing penetrations, or any other area where the building's structure is not completely airtight. Unintentional airflow can result in air leakage, leading to energy loss, decreased indoor air quality, and compromised thermal comfort.

Good ventilation helps to remove pollutants, odours, excess moisture, and airborne contaminants from indoor spaces. It also prevents the build-up of stale air as well as mould growth in the damper months.

Techniques to manage airflow in homes include air sealing, adding insulation, installing mechanical ventilation systems, air filters, and regular maintenance to identify and repair air leaks. 

What are the building regulations for airtightness?

In the past year, England and Wales have implemented new building regulations aimed at strengthening the requirements for airtightness in new constructions. 

These regulations (Part L is the section of the building regulations that covers the energy efficiency of buildings) have reduced the limit for air permeability in new buildings from 10 m3/hr.m2 to 8 m3/hr.m2. Alongside this change, other significant updates have been made to the regulation of airtightness.

While the building regulation changes targets are not overly demanding, they mark the beginning of a process that is expected to lead to even stricter standards in the future with the UK targeting lower carbon emissions and greater energy efficiency in homes.

By improving airtightness, the regulations aim to minimise heat loss and improve the overall energy performance of new and existing buildings, which is also the aim of AeroBarrier. Tim Crump, founder of Oakwrights, the company introducing AeroBarrier to the UK, claimed, “Britain has some of the lowest performing and oldest housing stock in Europe, and there is a real and growing interest in improving energy efficiency and reducing environmental impact.”

Is AeroBarrier suitable for your project?

AeroBarrier is pretty versatile stuff. This means it can be applied to buildings of different types and sizes, making it suitable for both new build projects and retrofitting existing structures. It has already been used across the United States by architects, builders, and homeowners.

While AeroBarrier is highly effective at sealing air leaks, it is necessary to protect surfaces during the application process. The sealant may not adhere easily to vertical surfaces, but it does settle on horizontal surfaces.

As a precaution, windowsills and finished floors should be protected during the application to avoid any undesired contact with the sealant.

How much does AeroBarrier cost?

The cost of AeroBarrier can vary depending on various factors, such as the size and complexity of the building, the region, and specific project requirements. As a result, it is challenging to provide an exact cost without specific details.

Typically, AeroBarrier is priced per square foot of the building envelope that requires air sealing. Other factors that can influence the cost include the building's design, the number of air leaks present, and any additional services or features requested. For instance, if a building has a significant number of air leaks or complex architectural features, it may require more time and material to achieve the desired airtightness, leading to higher costs.

It is best to speak with a qualified AeroBarrier contractor or service provider to get a better idea of cost for your project as they can assess the requirements of your building.

A stunning Isle of Wight property owned by an architect behind one of Grand Designs host Kevin McCloud’s favourite projects is on sale for £2.25 million.

Lincoln Miles was lauded by the TV star after transforming a 1970s bungalow on a budget of £200,000. When it featured on the Channel 4 show in 2010 McCloud said: “It’s one of the great illusions of architecture, pulled off with utter bravado.”

Now Mr Miles’ other self build masterpiece on the Isle of Wight is set to go under the hammer. It is a former Second World War bunker with incredible sea views in St Lawrence, near Ventnor.

Brise soleil and fibre cement exterior

The property features a brise soleil – French for ‘sun breaker’ – an architectural feature of a building that reduces heat gain within that building by deflecting sunlight.

It is made using richlite, a durable material made from recycled paper, which was chosen to construct the fins for its resistance to the coastal elements and its angular perforations.

It was designed by artist Lisa Traxler, Mr Miles’ wife, as a nod to the ‘dazzle’ patterns of naval camouflage.

Cast concrete staircase curves down to a living space

A lightwell separates the dining space and kitchen in the three-bedroom home.

The kitchen is arranged around a worktop enamelled in the same ‘dazzle’ design and leads to a cast concrete staircase curving down to the double height living space where there is a log burner with a chimney wall.

Estate agents Spence Willard said: “Its towering concrete walls create a monolithic cave-like setting and have been used by the current owners as a gallery and events space, though it could be brilliantly repurposed for entertaining, dining or a recording studio.”

'Bubble-gum aluminium' clad chimney breast

The chimney wall is clad in a ‘bubble-gum’ aluminium design. Also in the living space is wall of south-facing glazing that offers sea views beyond rolling fields.

Meanwhile, there are three bedrooms on the first floor, two of which enjoy sea views and share a wide balcony.

Spruce clad ceilings with polished concrete floor

Polished concrete with underfloor heating runs throughout the property and the walls feature fair-faced blockwork and spruce cladding overhead.

The doors and windows use a prototype framing system employing paper composite material to achieve their massive spans and heights, which exceed three metres in places, while minimising the frame profiles.

The result is a “stripped-back aesthetic that belies the fastidious engineering throughout.”

Converted Nissen hut outbuildings with log burners

In the one acre site southeast of the main house are two Nissen huts which would have been occupied by defence forces during the Second World War. These have been repurposed as studio spaces where the couple work.

Nissen huts were prefabricated steel structures used extensively in the Second World War, especially as barracks.

They are internally clad in OSB, or oriented strand board, insulated, and each contains a log burner and washing facilities.

The listing states that the “huts could easily be run as holiday lets or be used as ancillary accommodation”.

A bathroom is one room in the home that experiences high moisture and condensation, especially when running a hot bath or shower. Without bathroom ventilation, moisture will remain in the air and seep into surfaces. As soon as this happens, mould will start to grow where you don’t want it.

Natural ventilation is part of a good ventilation mix in a bathroom, but it's not always a viable option. Here, we look at why bathroom ventilation is important, the best ways to address it, and the different types of extractor fans that can help provide the right level of ventilation.

The importance of bathroom ventilation

Bathrooms are hardworking spaces, and daily, they experience significant fluctuations in moisture and humidity due to the activities that take place there. Rather than spending your time dealing with mould in bathrooms, it is better to prevent it from forming in the first place.

"The bathroom is one of the major sources of moisture in the home and tends to be used for bathing and showering daily," says Chris Michael, Managing Director of Meaco. "Without good extraction, the levels of moisture will build and build, which can result in mould growth within the room.

According to Victoria Plum: "Water vapour equating to as much as 10 litres can be released inside your home daily, which, unless extracted, can reduce air quality and lead to the formation of mould and damp."

While other rooms in the house will also contribute to this water vapour, the large amounts of water produced by bathing, washing, and showering every day in the bathroom make it particularly essential to address the moisture in this space.

Try these to help improve bathroom ventilation

Best way to ventilate a bathroom

Installing mechanical ventilation is the best way to ensure your bathroom remains well ventilated. For most people, this will mean installing an extractor fan.

That said, if you have mechanical ventilation with heat recovery (MVHR) installed in your home, fitting an extractor fan will be unnecessary – in fact, it could actually interfere with the MVHR's performance.

"The bathroom is one of the main sources of heat that the MVHR system is trying to recover, so an extractor fan would actually be detrimental to the system," explains Tim Pullen, an expert in sustainable building methods and energy efficiency in residential homes and author of The Sustainable Building Bible, amongst other titles.

"It would suck all that lovely warm air resulting from your shower and exhaust it to the atmosphere, rather than recirculating it to warm the air being delivered to the bedrooms, lounge, etc."

If you are going to be relying on an extractor fan, be sure that it is positioned correctly in order to make the most of it. Fans should be positioned as high as possible on the wall, close to the main source of steam and well away from any sources of 'replacement air' such as windows.

"A bathroom fan shouldn’t be installed just anywhere. Fans that are suitable for wall, ceiling or window installation make choosing where to locate the fan much easier," says Natasha King, RMI Product Manager at Vent-Axia. "In larger bathrooms a fan can be installed safely away from any sources of water spray. But in smaller rooms, such as an en suite, this may not be possible. In these cases, a fan with an IP45 rating (for Zone 1) can be safely installed in the splash zone.

"Another feature to look out for is variable speed models, where fan speed can be adjusted to meet the individual airflow needs of the project – this is especially helpful with long duct runs. Plus, variable speed models can be altered to achieve the required airflow at a sound level that is acceptable to an individual household."

Types of extractor fans for bathrooms

In order to get the ventilation spot on in your room it is important to choose the best bathroom extractor fans for your needs. There are three main types of extractor fan, each suitable for different situations:

• Centrifugal fan: This type of extractor fan is perfect if your bathroom is located more than 1.5 metres from an external wall. Centrifugal fans – which are commonly fitted into ceilings – are more powerful than other types of extractor meaning they can move air further. On the downside, they are often a little noisier than other models due to their powerful motors.
• Axial: If your bathroom is 1.5m or less from an external wall, an axial extractor fan may do the job of removing stale air just fine. They are less powerful than centrifugal fans and are therefore usually quieter too.
• Inline: In some cases neither of the above types of extractor fan will be sufficient to ventilate your bathroom – this is where inline fans come in. These fans are designed to be capable of moving stale air much longer distances than either of the above – often at least 40m.

There are also a whole host of newly developed features to look out for when selecting a bathroom extraction fan, many of which will improve the indoor air quality (IAQ) in the space further.

"Intelligent, fully automatic humidistats are also a great addition in the fight against moisture," says Natasha King. "Fans with this feature, such as Vent-Axia’s PureAir Sense, learn to run only when they can make a difference to IAQ. It can also sense when someone is in the room and then activate the fan. These intuitive sensors can reliably recognise room occupancy through light movement and shadows, but can distinguish between car headlights flashing and people moving about to avoid nuisance running."

She adds, "Additionally, the delay-on feature avoids the fan being triggered in the night during quick bathroom visits. Finally, an airing function is ideal for those who are away a lot or for a guest bathroom. This runs the fan for an hour if it has been inactive for over a day, ridding the room of stale air and stuffy, musty odours."

Choosing the right size

Along with choosing an extractor fan that will suit the location of your bathroom in your home, it is really important to select the right sized model – too small for the space and the money you spend on it could well be wasted, too big and you will be using more energy than you need.

"First up is making sure the fan you choose is up to the job. This means it meets the air change requirements for the room, to ensure that steam and smells are removed at source," says Natasha King. "This not only prevents condensation and mould appearing in the bathroom, it also stops moisture migrating to colder parts of the house and causing damage around the home."

You need to base your choice of fan on its extraction rate – the amount of air that can be removed from a room in an hour. The extraction rate will usually be measured in m3 per hour – m3/hr.

Next you need to turn your attention to 'air change'.

"For bathrooms it’s recommended that you should have four air changes per hour (you may wish to increase air changes depending on the size of the bathroom) with an extract rate of no less than 54m3/h at 15 l/sec. Alternatively, you could ventilate continuously at 0.3l/s/m2," says Natasha. One l/s is approx. 3.6 m3/hr.

In order to work out the extraction rate you need, calculate the size of your room in cubic metres by multiplying the height, width and length of the room – so, for example, if your bathroom measures 3m high x 3m wide x 2m long, you would carry out the following calculation:

3m x 3m x 2m = 18m3.

This means that in order to change the air in that room once an hour, a fan would need an extraction rate of 18m3/h. For the room to have the required four air changes per hour, you would need a fan with an extract rate of 72m3/h (4 x 18m3/h).

FAQs

What are ventilation building regulations for bathrooms?

The type of ventilation required by the building regulations will depend on your bathroom but, unless you have a bathroom with no windows, there is no legal requirement for you to fit an extractor fan. That said, relying on a window alone to ventilate your bathroom is going to leave you very chilly in the winter months.

In new bathrooms, with a bath and shower, mechanical ventilation is required – and this means an extractor fan or MVHR. In a bathroom, you will need to fit a fan with a minimum extraction rate of 15 l/s.

If, on the other hand, you are renovating a bathroom that currently has only a window for ventilation, there is no requirement to install an extractor fan – but it is highly recommended that you do, particularly if you are looking at how to stop condensation, mould and damp from becoming problematic.

Is my extractor fan working properly?

If you are renovating a bathroom with an existing extractor fan there is an easy way to check that it is working.

"A good extractor fan is essential in keeping a bathroom dry and there is a simple test that you can do to judge whether your extractor fan is up to the job," says Chris Michael. "Take a sheet of A4 paper and hold it up to the extractor fan, if it sticks, then the suction from the fan is good and the extractor is doing its job, if the paper falls to the ground, then the extractor needs cleaning or replacing."

Can you use a dehumidifier in the bathroom?

Dehumidifiers are a great way to reduce the humidity in a room and to keep it free of condensation, damp and mould – however, they cannot be used in bathrooms.

"A good option would be to place a dehumidifier on the landing or hallway outside your bathroom or shower room," advises Meaco's Chris Michael. "If you leave the bathroom door open once you have finished, then the damp air in the room will naturally move towards the dehumidifier (damp air migrates to a dry spot) and the dehumidifier will keep the bathroom and the landing and bedrooms dry without the need to have the dehumidifier in the actual bathroom.

"An added bonus is that the towels in the bathroom will dry faster as well. This solution is helpful where you don’t have an extractor fan and you don’t want to or can’t leave a window open."

Dehumidifier running costs might not be as high as you think and you can also use them to dry clothes quickly.

If you’re renovating a bathroom, you need to consider more than just ventilation. Check out our guides on Where to buy bathroom tiles, bathroom layout mistakes to avoid and some smart modern bathroom ideas.