I reviewed the Aranet4 HOME monitor to see if the air quality in my home was cause for concern. I learnt more than I thought I would

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.

Image 1 of 2

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.

Image 1 of 3

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.