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Health and low energy buildings

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) held a conference last week on the topic “Environmental Health in Low Energy Buildings.” Although you wouldn’t necessarily guess it from the name, the society is a lively, welcoming group of folks from all over the world interested in improving the built environment. At this conference, the focus was on two aspects of the built environment — indoor air quality (i.e., IAQ) and energy efficiency. My interest in going was on exploring the potential downstream applications of my work on the microbial ecology of the built environment, plus seeing if I could incorporate things into my research that might be readily “translatable” to practicing engineers.

Strategies to lower the energy use in buildings often work by reducing the air exchange rate, which I have come to interpret as the number of times in an hour the air in a room is replaced. (I heard at the conference that in practice the number for the AER and the physical replacement of air are slightly different, but I gather through discussion this is a good enough approximation.) This makes sense — once you’ve heated air to a comfortable temperature, it’s less energy to keep it in the room or recirculate it through the house than to take (hopefully fresh) outdoor air and heat it all over again.

In one of the plenary talks, Mark Mendell of Lawerence Berkeley National Lab questioned, what are the health effects of these low-energy strategies that reduce air exchange rates? He seemed to caution that, although we don’t know much definitely, the available data shows it’s not good. For instance, many talks of the conference noted that at lower air exchange rates, compounds like carbon dioxide and indoor-generated pollutants such as formaldehyde are higher, and these properties have been linked to, among other things, poor decision-making and respiratory distress.

In another plenary talk, Rich Corsi of UT Austin summarized the main problem of the conference topic: measuring the success of energy efficiency is straightforward because it’s one-dimensional, whereas determining the indoor air quality is multi-dimensional, and it’s not yet clear what are the important chemicals and properties to measure. He spoke about the reactivity of surfaces in producing indoor-generated compounds; from what we do know, we don’t know how that changes in energy-efficient buildings. In other words, to really figure out how environmental health is affected by low-energy buildings, ASHRAE — and those interested in the build environment — have their work cut out for them.

The biological components to these issues are not well known, and I can say without a doubt that there is a lot of room for biologists and their work in this topic. For example, in many talks the generation of certain compounds was often classified as “microbial”, a contrast to those generated through chemical or physical processes. Plus, microbial presence was typically measured using broad, traditional techniques like spore counts and total fungal biomass. While these metrics are informative, we know that they only scratch the surface of microbial ecology. That was one reason it was great to see an update from Shelly Miller at CU Boulder on the work she and others are doing characterizing the microbiology of homes from a microbial ecology and indoor air quality perspective. Going to a conference full of engineers reminded me quite clearly – The microbial black box of the indoor environment is one we are still trying to fully understand.

I heard that the slides from the plenary talks – which are definitely worth checking out – will eventually be posted online at the ASHREA website.

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