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.

Unfortunately we do not seem to be very sensitive to the high relative humidity and other pollutants than are, nonetheless, dangerous to our health – but we are sensitive to draughts, and noise. This means that vents get closed and fans shut off, and our living conditions are unhealthier than they should be as a consequence.

What was interesting was to find that poor indoor air quality is not a new problem; studies dating back to long before airtightness was much of an issue, showed similarly poor indoor air quality and low ventilation rates. So the comfortable belief that natural ventilation is somehow “tried and tested” probably needs revisiting.

We seem to be facing a ventilation performance gap as worrying as the energy performance gap. As with energy performance, designers seem to have checked compliance with the Part F recommendations, looked at the results from their modelling exercises, and assumed this means a building is going to be properly ventilated in practice. As with energy performance, monitoring data shows this just isn’t the case.

At least the energy performance gap is now on the agenda – and we are even getting some practical solutions discussed. But despite the huge costs to the nation of respiratory diseases like asthma, and numerous other ailments worsened by poor air quality, ventilation is too often taken for granted. It’s probably time this changed.

 Read the article in pdf here Natural ventilation – does it work?

My thanks to Passive House Plus for the use of this document.

I have now added a post containing links to a number of the references used in this article, here.


Passive House goes large

Passivhaus is no longer just the preserve of the self-builder: more and more large Passivhaus schemes are being announced. These include both non-domestic buildings, for example in schools and universities,  and multi-housing schemes, generally in the social rented sector, though sometimes with a portion for private sale.

In this article for Passive House Plus magazine I looked at some of the economies of scale available on larger Passivhaus projects, and some of the obstacles that larger schemes may run into. Also, following from my previous article on the cost of Passivhaus, I looked a bit further into the economics of Passivhaus from the point of view of developers and owners – in both the domestic and the non-domestic sectors.

Read the article in pdf here: Passive House goes large

My thanks to Passive House Plus for the use of this document.

The cost of building passive

Passivhaus (Passive House) is often thought of as being “too expensive” for the mainstream. There are some designers and developers however who are managing to shave the capital cost premium down to just a few per cent – or even zero.

In researching this article for Passive House Plus I learned that the extra costs, where they are incurred, seem to derive from two main sources:

  • Passivhaus components tend to be more expensive than the “conventional” alternatives – though this difference is diminishing all the time; and
  • There is a “learning curve” in first (and probably second and third) Passivhauses for any team, where designers and contractors alike need to spend a bit longer working out how to co-ordinate their activities to ensure that details are buildable, and that built quality matches up to the standards sought.

The extra costs are mainly up-front; looked at over the building’s first decades of lifetime, running cost savings – including maintenance, and even cost associated with tenant dissatisfaction – start to pay back the initial investment.

Of course a key question is “costs compared to what?” – and as statutory building standards edge upwards, you might expect the “standard” and Passivhaus build costs to converge – thus, for example, mechanical ventilation is increasingly commonly installed in non-Passivhaus dwellings, simply because Part L of the building regulations is looking for more energy efficiency and hence higher airtightness.

However, a couple of caveats:

  • Mainstream dwellings built even to high notional standards may employ cheaper construction “models” with less quality control, and therefore, leave bigger performance gaps; and
  • Passivhaus is offering more than just energy savings, it is also concerned with comfort and occupant health – something that has clear value, but is perhaps hard to price in the context of a shortish article.

I was particularly interested in the perspective from some of the people I spoke to, suggesting that insulation (literally!) of occupants from rising and unpredictable energy costs was not only attractive to owner-occupiers, it was also attractive to landlords and to lenders, as problems with soaring energy bills appear to be playing an increasing part in rent and mortgage arrears – making a Passivhaus building a better bet for investment.

Several people suggested to me that if building standards (and testing standards) were set higher, “levelling the playing field”, this would reduce the competitive advantage of low-efficiency, shoddy building – and with it, reduce the cold wind that whistles though the performance gap and straight into occupants’ wallets.

Unfortunately, to bring about this kind of improvement, I can’t help feeling big developers would have to devote less energy to lobbying for the status quo, and more to changing their modus operandi. But with the first record of a Passivhaus building (in Frankfurt) offering heat “too cheap to meter”, customers may yet demand the same here.

Read the article in pdf here: The cost of building passive

My thanks to Passive House Plus for the use of this document.