I’ve had a couple of requests for links to the sources for “Natural Ventilation – does it work?”, my article for Passive House Plus Issue 6 (start of 2014), so here is a list of most of them – live as at the time of posting in April 2014, but no guarantees they will remain so of course. Continue reading “Does Natural Ventilation Work? – References and Links”
Tag: ventilation & health
Healthy buildings – feature in Green Building magazine
Most people spend 80 – 90% of their time indoors, which means the indoor environment is where people meet many of the influences that affect their health and wellbeing, for good or ill. The impact is serious: just one condition affected by the indoor environment, asthma, kills three people a day and costs the country millions of pounds annually.
We all want the buildings we create and occupy to be healthy, and the sustainable building world often makes special claims to be creating healthy spaces. But are we directing our attention the right way? Which hazards are most important – and which can we actually do anything about?
In this article for the Spring 2014 issue of Green Building magazine, I have a look at the indoor hazards that might affect out health, and consider which ones we can do anything about – and how they might be tackled.
Download the article in pdf, for references and links: Healthy Buildings
Natural ventilation – does it work?
While mechanical ventilation is sometimes perceived as problematic, expensive and possibly even energy-guzzling, natural ventilation often seems to be seen as – well – “natural” – a safe, old-fashioned, reliable default solution. In this article for Passive House Plus I had a look at this assumption.
Theoretical modelling suggests that natural ventilation is likely to be rather unreliable, with the same building at risk of both under- and over-ventilation under different weather conditions. But what happens in practice?
The first problem I had was finding some data: there is very little of it.
In the studies I was able to find, it turned out that indoor air quality in naturally ventilated homes (including levels of relative humidity, oxides of nitrogen, and volatile organic compounds, for example) is not what it should be. (I also found some studies from schools raising similar concerns, but there wasn’t room to write about these as well).
For example, a study of 22 homes built to the 2006 Part F regulations for ventilation found that about half of them failed to achieve their recommended background ventilation rate even with all vents open/fans running as intended; pollutants exceeded the guideline levels in a number of them.
But what was really worrying was that when the researchers first arrived, they found that many of the vents were closed, and many of the extract fans (both in bathrooms and kitchens) had been disabled at the isolator. Similar findings appeared in all of the studies I was able to track down. Continue reading “Natural ventilation – does it work?”
Can Passivhaus teach the policymakers to love the occupant?
Ventilation was much in my mind as I dipped in and out of conversations and seminars at Ecobuild this week. And I began to notice a disturbing tendency for airtightness measures and ventilation to be discussed quite separately, with the costs and benefits of each addressed almost as though the two were unrelated.
Again and again, ventilation appeared to be an afterthought, or a problem, instead of an integral part of the assessment of building performance. Several people also lamented that “well, you can get draft proofing done on a Green Deal, but ventilation doesn’t meet the golden rule, so who will pay for it? – it can’t be funded”. And alarmingly, this dangerous split seems to be reflected in the very structure of the Green Deal.[1]
This strikes me as rather like saying “you can get this operation that you need, but there is no money to sew you up afterwards”.
Ventilation seemed almost to be resented, an ‘obstacle’ in the way of deeper carbon cuts, limiting what could be achieved. All that fresh air spoils the building performance, it seems.
This put me in mind of a similar flavour you find in discussions about ‘comfort taking’. Once again, the pesky needs of the occupants are getting in the way of the true goal of carbon cutting. Thus in its Green Deal Impact Assessment DECC complained that “comfort taking” leads to “underachievement in real-world energy savings”.[2] Is it really an “underachievement” to make someone’s house more comfortable?
In both these instances, there is a not-so-hidden subtext that the base animal needs of building occupants are a real hindrance to the low-energy, zero carbon perfection we are seeking. And in a way, you can see how if your job is to achieve these goals, a building with no occupiers would solve a lot of your problems.
So it might be unexpected in a way, that it takes Passivhaus, possibly the most shamelessly geeky and science-based standard of them all, to be the one that not only embraces the occupant, but actually starts from the occupant perspective. My understanding of Passivhaus design is it is built from the premise that occupants want comfortable, healthy buildings that are cheap to run. And yet, somehow, it looks as though Passivhaus manages to deliver the lowest energy and (I think you could easily argue) lowest emissions buildings of the lot of them.
Which is why (or at least one of the reasons why), as I remarked on Twitter this morning, I found that Passivhaus crept into my mind quite often, when I was pondering my uneasiness with what was being said outside the Passivhaus sessions. I think the Passivhaus lot are on to something.
[1] I was told that for post 1919 buildings there is not anything in the Green Deal that requires the advisors to assess ventilation, even when they recommend draftproofing. There are especially serious concerns about the mass-scale installation of solid wall insulation, where the installer alone is responsible for the ventilation strategy, with no back-stop liability resting with a Green Deal provider. This is an issue that needs more than a blog to tackle – hopefully I will get the chance to come back to this soon.
[2] DECC June 2012 Green Deal Impact Assessment