The healthy home — it sounds a bit abstract, right? Like something that surely can’t exist in reality, a bit like Feng Shui, Ley Lines or Laurence Llewelyn Bowen. Hardly the stuff to obsess the rest of us. It’s easy to dismiss, for sure, as a meaningless and slightly dubious ruse by the eco warrior lobby. All concept, no science.
Well, you would be wrong. “Britain is finally waking up to a concept that has been mainstream in housebuilding in mainland Europe, particularly Germany, France, Spain and Italy, for many years,” says Thomas Gartner, partner at Gale & Snowden Architects in Devon and a Director of the British arm of the Building Biology Association.
Baubiologie (building biology) began in Germany in the 1970s, and in the 2000s international movements sprang up in North America, Australia, Japan, France, Spain — the list goes on. But Britain has only had its Building Biology Association since 2014. It’s still the German-based Institute for Building Biology and Sustainability (IBN) which administers the Healthy Home Standard (you can find out a lot more about it, and the key principles, at baubiologie.de).
For now, the UK arm runs courses for interested designers and does a bit of promotion around the concept of healthy homes, but one senses that, a bit like Passivhaus in the UK in about 2008, there is a surge in interest waiting to happen.
That said, it’s early days, according to Oliver Rehm, MD of Baufritz, the German timber frame company who specialise in healthy homes (covering light, warmth, acoustics, air quality and more). “For us, it is the most important part of our philosophy and building concept/system. Only a healthy home can be an ecological one that is good to humans and nature.”
What is a Healthy Home?
So what does it actually mean? As Thomas Gartner puts it: “For years we have concentrated on the impact that humans have on the environment. The Healthy Home Standard looks at the impact the environment has on humans.” It looks at how an individual’s health is impacted by five categories:
- the site
- the environment
- interior design
- the indoor climate.
These are addressed through all of the major elements of a homebuilding project, namely the design, the specification and of course the building physics.
Indoor Air Quality
As we spend more of our time in our homes than ever, we give surprisingly little thought to the air we breathe there.
VOCs (Volatile Organic Compounds)
Dr Derrick Crump, Director of the Institute of Environment and Health at Cranfield University, says that, since the 1950s, as our lifestyles have become increasingly based in buildings rather than spent outdoors, it is illogical to concentrate on traditional air pollution issues (e.g. vehicle exhausts) at the expense of the quality of the air in our buildings. Which for most of us really means our homes — and as those most vulnerable to pollutants spend disproportionately more time at home (elderly, newborn, sick) it becomes all the more important that we consider our indoor air quality (IAQ — yes, it’s a thing).
As Dr Crump says: “Our indoor air quality is affected by three main factors: Longer-term emissions from materials in the building fabric and furnishings; our own activities, such as cooking, and ourselves, through things like perfumes and washing detergents.” The main issue is around reducing or eliminating the amount of new toxins released into the internal air — and of course ensuring adequate ventilation to ensure they can be removed quickly.
VOCs (volatile organic compounds) are essentially chemicals that are not acutely toxic but over the long term can ‘off-gas’ toxins; a significant and accepted body of research links long-term exposure with health problems (specifically headaches and nausea, fatigue, eye irritability and a few others). The most harmful VOC is formaldehyde, which is present in most conventional oil-based paints and even present to a small degree in acrylics — although, as it has no smell, it is not the cause of the overwhelming aroma that paint gives off.
VOCs are also present in many other building materials and some of the larger (and more responsible) manufacturers have been taking steps to address concerns. British Gypsum’s ActivAir technology, for instance, is added to some of its plasterboard and plaster ranges and aims to decompose formaldehyde emissions into non-harmful compounds — it even works through emulsion.
One of the main areas of concern is the levels of VOCs in particleboard and MDF. One theory is that this is due to the bonding element of the wood, but studies have shown variations in terms of VOCs depending on the type of source wood (e.g. southern pine) used. Most experts believe that it is actually the degradation of the wood that causes VOCs to be present. However, manufacturers now have to meet British Standards when selling MDF (it is tested at BRE in Watford) and off-gassing is likely to be a tiny proportion of what it was when these products first came out in the 1960s. Look out for formaldehyde-free boards (it is used as a binding agent) and where possible source your boards from inside the EU, where low-emissivity boards are required as standard.
The number of paint manufacturers selling low-VOC or VOC-free paint has grown significantly in recent years, with even the major manufacturers supplying ranges low in solvents (e.g. Crown’s Breathe Easy and Dulux’s Ecosense). It’s worth checking out the leading ‘eco’ paint suppliers such as Ecos Paints, Earthborn and Little Greene.
Mould – something those of us in colder homes in our typically damp climate have all experienced, usually in wet areas such as bathrooms – is a big issue, particularly for those with asthma. Around 3-4% of the population, and 10% of those with allergies (according to Asthma UK) experience symptoms when in contact with mould spores (which are released into the air by mould and, outside, would usually be blown away by the wind). The rest of the population have immune systems that get rid of them through sneezing or coughing.
As the risk of asthma attacks is heightened by exposure to mould, the answer lies in removing it from your home. Warmer external walls are key, as is adequate ventilation. A combination of the two is usually sufficient. In new build homes it is usually never an issue — but renovators need to account for it in their design and build. Ventilation solutions can either be mechanical – e.g. MVHR (mechanical ventilation heat recovery) units – or passive (using natural air flows to ensure fresh air — try Ventive).
Managing ventilation is key to reducing humidity in the home, but there are quicker fixes, such as Dimplex’s Forte dehumidifier (£129-£179 RRP)
Allergens in the home can be reduced by limiting the number of fabric-based surfaces (which tend to harbour dust mites, pollen, etc) and replacing them with harder surfaces (so, for example, specifying hard floors rather than carpet). The same principle applies to furniture and window dressings.
Clearly, reducing the amount of unfiltered air entering the house is key (so airtightness is something to aim for) while at the same time fitting mechanical ventilation systems with filters is essential — the amount of dust is also significantly reduced. Of course, this relies on the filters being changed/maintained on a regular basis — most people who install MVHR units never touch them again.
A simpler option for those less committed to installing a mechanical ventilation system is plug-in air purifiers such as Dimplex’s Pur-80 Air Purifier, which is able to capture dust and pollen with low power consumption.
The Key Elements of a Healthy Home
- A site without disturbances
- Homes away from sources of emissions and noise
- Sufficient green space
- Best possible quality drinking water
- Minimising energy consumption and using renewables where possible
- Local materials where possible and responsibly sourced
- Natural building materials
- Materials with low radioactivity levels
- Materials with noise and vibration protection
- Pleasant or neutral smell with no off-gassing toxins
- Natural light conditions
- Consideration of ‘harmonic’ proportions
- Natural regulation of indoor air humidity through humidity-buffering materials
- Low overall moisture content of home that dries out quickly
- Optimal air and surface temperatures
- Good indoor air quality through natural ventilation
- Heating system based on radiant heat
There’s clearly a difference in how you’d feel being locked in a dark room as opposed to standing a sunny room. Of course, the difference in the amount of light (both natural and artificial) in our homes is a bit more nuanced than that, but the principle is the same. In essence, the more natural light the better — a common phrase you’ll hear from people who have built homes with large amounts of glazing is that they feel more connected to the seasons, good and bad. Here, the window to wall ratio (WWR) becomes a consideration.
The WWR is derived from the area of windows or glazing divided by the area of walling. Over the course of a whole elevation, a typical WWR would be around 30%.
It varies by elevation, of course — Passivhaus design principles usually result in minimal glazing to the north and large openings to the south to maximise solar gain and reduce heat loss. Clearly, big glazing provides its own problems — usually resulting in a requirement for triple glazing that has a cost impact, as well as potential overheating, which can be overcome to an extent by overhangs and shading.
Light quality is a key issue and can be quantified. Indeed, the now defunct Code for Sustainable Homes offered credits for ‘daylighting’ and required the following:
- Kitchens to achieve a minimum average daylight factor of at least 2% (the average daylight factor is, roughly speaking, the ratio of the internal light level to the external light, but it’s more complicated than that)
- Living rooms and studies achieve a minimum average daylight factor of at least 1.5%
- 80% of the working plane in most ‘day’ rooms such as kitchens must have a view of the sky (the working plane is the level which most of us work at, e.g. head height)
Details of how to achieve these in reality appear in British Standard BS 8206-2.
Artificial lighting is a highly complex field, as Thomas Gartner explains: “Artificial lighting can have a huge impact on our melatonin and hormone levels, which can affect our sleep or energy patterns,” he says. “We tend to need reddish light in the evenings to boost melatonin and help us sleep, whereas in the day, more blue-ish light is desirable as it’s stimulating. Modern LEDs offer varied qualities of colour spectrums to make up their white light, and very few are really up to scratch, often having too much blue in the spectrum.”
To add to matters, low-energy glazing coatings can block out certain hues, causing related issues. “We check all the glazing we specify with a spectrometer, which measures the properties of light passing through the glass,” says Thomas Gartner.
Light quality is a key element of Saint Gobain’s Multi-Comfort House standard, which applies science to the issue. “Daylighting autonomy is a dynamic analysis tool that shows the amount of time a space is above the required illumination levels,” says Saint Gobain’s Stacey Temprell. “This can considerably help the lighting designer, from specifying additional artificial light to helping understand the behaviour of natural light — a very different subject. As our living habits change, so will our lighting needs.”
Noise is becoming a major factor in our homes and it’s surprising how recently it has become such an issue. In the 2008-published Code for Sustainable Homes, noise was a component that designers could gain credits against, but the criteria related to successfully prohibiting noise exiting the home (and affecting neighbours) rather than managing acoustic quality within the home.
The Healthy Home Standard reverses this approach and deals with acoustic quality in two respects: stopping noise entering the home in the first instance and also managing acoustic performance within the home itself (e.g. not being able to hear people using the toilet upstairs while you’re in the kitchen).
It’s hardly news to people who live on busy roads or in the middle of towns or cities, but the impact of external noise can be damaging to our health (mainly by impacting on stress/anxiety levels and affecting our sleep quality). The Healthy Home Standard suggest that this be considered in the design stages — for example by positioning main bedrooms in the quietest parts of the site and minimising exposure to the road elevation for outside spaces (for example designing in courtyards). Of course that’s only really possible depending on your individual site.
The good news is that it’s measurable. Outdoor-Indoor Transmission Class (OITC) is used to measure the transmission of sound between inside and outside and the performance of materials (windows and doors) that act as the barrier. So a door with a stated OITC of 30dB will reduce an outside sound of 70dB to an internal noise of 40dB.
For walls, the measurement is Sound Transmission Class (STC) but the principle is the same. Acceptable measures can be achieved through either double or staggered stud walls or, more easily, solid masonry walls in excess of six inches thick. This can, of course, be further improved through acoustic-performance plasterboards (British Gypsum carry some very interesting solutions) but do check that these can satisfy other aspects of a holistic healthy home criteria.
External Emissions: Electromagnetism and Wireless Signals
Electromagnetic sensitivity – a syndrome caused by exposure to wireless emissions – is recognised in some countries as a disability (such as Sweden) but not in others. The UK essentially ignores any consideration of mobile or wireless frequencies as problematic (in spite of World Health Organisation studies which stated that they were potentially carcinogenic), whereas, for instance, France has established areas without wireless networks. In essence, it leaves the sufferer with nausea, headaches and fatigues when exposed (to Wi-Fi, mobile antennas, and so on).
As you can imagine in today’s modern world, it’s almost impossible to prevent exposure in our everyday lives. However, you could move to Green Bank, North Carolina (where the presence of the world’s largest radio antenna prohibits the use of wireless signals within a 10-mile radius — as a result it has attracted dozens of sufferers who have set up home there) then essentially insulating your home is the answer.
The conventionally built home wall (whether it’s timber or masonry) will typically allow wireless signals to penetrate (as anyone who has ‘borrowed’ Wi-Fi from the neighbours will know). However, some package suppliers and construction specialists are now able to adapt the construction in order to provide a barrier. Baufritz, the German timber frame package supplier, are leaders in this field and have developed an electro-smog radiation barrier – they call it the Xund-E – as an inner coating on their external walls and roof. This is part of their wider strategy for providing healthy homes, which includes many of the concepts talked about in this article.
“We don’t charge extra for the ‘healthy home’,” says Oliver Rehm, Baufritz’s MD. “However the purchase of natural building materials, that are toxin and emission tested, is more expensive than commonly used materials. Our purchasing department, engineers, architects and installers are specifically trained on healthy building methods and construction. You can only build healthy homes if you have the right people who believe in this and do not make any compromises.”