Project at a Glance

Title: Indoor Environmental Quality and HVAC Survey of Small and Medium Size Commercial Buildings. Field Study

Principal Investigator / Author(s): Bennett, Deborah

Contractor: University of California, Davis

Contract Number: 06-311

Research Program Area: Health & Exposure

Topic Areas: Health Effects of Air Pollution, Indoor Air Quality


Ninety‐six percent of commercial buildings in the United States are small‐ to medium‐sized, use nearly 18 percent of the country’s energy, and shelter a large proportion of population, thus underlining the importance of understanding the relationship between ventilation, energy use, and air quality. This field study of 37 such buildings throughout California obtained information on all aspects of ventilation and levels of indoor air pollutants. The study included seven retail establishments: five restaurants; eight offices; two gas stations, hair salons, healthcare facilities, grocery stores, dental offices, and fitness gyms; and five other buildings.

Sixteen (43 percent) of the buildings were not designed to or did did not provide mechanically supplied outdoor ventilation air. In some cases the air handling unit was a residential rather than a commercial model, thereby failing to meet applicable ventilation standards. Low‐efficiency air filters were frequently observed. The air exchange rate averaged 1.6 with a standard deviation of 1.7 exchanges per hour and was similar between buildings with and without mechanically supplied outdoor air, indicating that buildings have significant leakage, in contrast to California homes. Compared against Title 24 standards, healthcare establishments, gyms, offices, hair salons, and retail stores were ventilated below the required rates, not meeting Title 24 ventilation requirements; restaurants and gas stations had rates above the standard, meeting ventilation requirements.

Indoor/outdoor ratios of ultrafine particulate matter and particulate matter smaller than 2.5 microns 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 ratio was 0.72, indicating that the building shell and heating, ventiliation, and air condidtioning system provided partial protection from outdoor particulates. Aldehydes and volatile organic compounds were measured. The majority of buildings had formaldehyde levels above the Office of Environmental Health Hazard Assessment 8‐hour reference exposure level.

Recommendations based on this study’s finding are: (1) require a mandatory inspection to confirm that appropriate mechanically supplied air is supplied; (2) increase formaldehyde source control; and (3) require increased air filter efficiencies.

For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753

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