ASHRAE Journal - October 2011 - 90

IAQ APPLICATIONS

Theory Meets Practice
A
By Lawrence J. Schoen, P.E., Fellow ASHRAE

Indoor Air 2011

s engineers and members of the ASHRAE community, we focus on the application principles used to design and maintain

healthy, comfortable and productive indoor environments. Underlying our practical work is the science of indoor air and human health. That science comes in large part from a community of researchers and practitioners, many of whom are active in ISIAQ, the International Society of Indoor Air and Climate. Some individuals (myself included) are also active in ASHRAE.
ISIAQ has historically run two series of conferences that take place every three years: Healthy Buildings and Indoor Air. From June 5 to 10, Indoor Air 2011, the 12th International Conference on Indoor Air Quality and Climate was held in Austin and organized by University of Texas. There is no way to write a short article that does justice to all the content of a ﬁve day conference that often had eight parallel sessions. Instead, this article gives my perspective on a few of the sessions I attended and my personal takeaways as a practitioner. Any omissions say nothing about any paper or presenter and might mean simply that I did not attend the session. I have grouped papers by several subject areas: particles and ﬁltration; thermal comfort; green building rating systems; ventilation and design standards; climate change; and residential applications. ticles, research and regulation have followed suit. While there is new and interesting work being done on the socalled ultraﬁne particles that are 0.1 microns and smaller, more “mature” science and regulation are in the ﬁne particulate range (PM 2.5). The good news is that we have effective technology to remove particles in this size range, and there is increasing evidence that it has a positive health outcome. I was particularly interested in the scientiﬁc and health basis of concerns about ﬁne particulates and the beneﬁts of particle ﬁltration from a plenary given by Bert Brunekreef, Ph.D., of Utrecht University, Netherlands. As pointed out by Brunekreef, the Harvard six-cities study published in the 1993 New England Journal of Medicine established measurable health effects of fine particle exposure. Higher exposure in traffic areas increases these effects as does time the individual spends in transport. Also, indoor particle levels have been shown to correlate with outdoor levels. A 2010 article by Macintosh in Journal
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Particles and Filtration
As advances in instrumentation have allowed the measurement of ﬁner par90 ASHRAE Journal

of Exposure Science and Environmental Epidemiology shows the benefits of high efficiency filtration and mechanical over natural ventilation. A 2011 paper by Allen in American Journal of Respiratory and Critical Care Medicine showed health effects in homes in a wood smoke impacted community. In that same Journal in 2008, Brauner showed how air filtration reduced indoor particles and improved vascular function. Environmental Health Perspectives published a paper by Janssen (2002) showing how the percent of centrally airconditioned buildings in a city decreases hospital admissions for heart and lung disease. Brunekreef said that outdoor air might be used for natural cooling but sound dampening grills, HEPA ﬁlters, and a fan are needed to clean it. I think it is great conﬁrmation that applications of particle ﬁltration of outdoor air entering buildings can reduce exposure and health effects. Among papers on the subject of particles, Alain Ginestet stressed the importance of pre-filters and showed that two filters in series (G4 and F7, which is about MERV-7 and 13-14) had better pressure drop without sacrificing filtration efficiency compared to a single filter. Electret type filters (a factory electrostatic treatment) have a sharp drop in filtration efficiency of about 90% to 30% after two to three months. Luiliu Du’s paper showed how standalone ﬁlters make a difference in reducing particulate matter in inner city residences, resulting in a reduction to about one-third (69% to 80%) of the level without a ﬁlter. However, its use by residents dropped over time. Lance Wallace, Wayne Ott and Neil Klepeis showed the high levels
October 2011

ASHRAE Journal - October 2011

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