ARB Research Seminar

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Small and Medium Commercial Buildings: Ventilation, Indoor Air Quality, and Energy Use

Photo of Deborah Bennett, Ph.D.

Deborah H. Bennett, Ph.D., Environmental and Occupational Health, Department of Public Health, University of California, Davis

April 06, 2011
Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA

Presentation: 1. 2.
Research Project


People spend 87 percent of their time in buildings, to shop and for health needs, but mostly to work. Small commercial buildings are the most likely workplace for non-industrial, non-agricultural American workers. In this first part of a two-phase study, a telephone survey and supplementary mail back survey were used to collect relevant details on ventilation and indoor environmental quality in small and medium-sized commercial buildings constructed after 1978 with floor area between 1,000 and 50,000 square feet and with no more than three stories. A total of 476 telephone surveys focusing on building characteristics and indoor air quality, and 71 supplementary surveys focusing on ventilation, were completed. A broad variety of air contaminant sources are present in small and medium-sized commercial buildings and building owners and managers did not know much about their Heating, Ventilating, and Air Conditioning system; the emission sources and concentrations; indoor air quality; and ventilation.

The field study of 37 small and medium commercial buildings (selected mostly but not entirely using the survey program) throughout California obtained information on all aspects of ventilation and levels of indoor air pollutants. Sixteen (43%) of the buildings did not provide mechanically supplied outdoor ventilation air. Low efficiency air filters were frequently observed in the air handlers. The air exchange rates averaged 1.6 ± 1.7 per hour; measured ventilation rates were compared against Title 24 standards. Ultrafine and PM2.5 particulate matter indoor/outdoor ratios were less than 1.0 in most buildings; exceptions were restaurants, hair salons, and dental offices, which have known indoor sources. The average black carbon indoor/outdoor particulate matter ratio was 0.64, indicating that the building shell and HVAC system provided partial protection from outdoor particulates. The majority of buildings had formaldehyde levels above the OEHHA (Office of Environmental Health Hazard Assessment, California Environmental Protection Agency) 8-hour reference exposure level. Recommendations will be presented.

Speaker Biography

Deborah H. Bennett, Ph.D., is Associate Professor, Environmental and Occupational Health, Department of Public Health Sciences, at the University of California, Davis. Dr. Bennett's current research interest fall into modeling and monitoring ambient indoor air quality in indoor environments; for example developing an indoor fugacity model to assess exposures resulting from indoor releases of pesticides and other organic compounds important for young children in homes where pesticides are used due to their increased contact with indoor surfaces and their hand to mouth activity. Dr. Bennett's model of the indoor environment, including air and indoor surfaces such as floors and walls is expanding to include the resulting exposure and she is investigating her model's applicability for use with other consumer products.

Dr. Bennett's interests and experience in field studies to support model development fit perfectly with the general thrust of the indoor air quality program at the Air Resources Board (ARB), whose contribution to the state-of-the-science in hazard assessment indoors and development of guidelines and educational directives for the citizenry and the legislature is known and appreciated. Professor Bennett has been enthusiastic and supremely giving in bringing additional resources, time, and energy to this complex and difficult task. ARB has welcomed the research that Professor Bennett and Dr. Michael G. Apte, her co-investigator, have made seminal contributions to the state-of-the-science in this area. Dr. Bennett attained her master's and a doctorate degree from University of California at Berkeley and a bachelor's degree in mechanical engineering from University of California Los Angeles. Professor Bennett has gained significant indoor air quality and energy efficiency experience and conducted research at Hughes and Lawrence Berkeley National Lab's venerable Environmental Energy Technology Division. Professor Bennett was an assistant professor at Harvard School of Public Health before assuming her current duties at UC Davis.

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