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THE EFFECT OF OPENING WINDOWS ON AIR CHANGE RATES IN TWO HOMES
Citation:
HowardReed, C, L A. Wallace, AND W R. Ott. THE EFFECT OF OPENING WINDOWS ON AIR CHANGE RATES IN TWO HOMES. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION 52(2):147-159, (2002).
Impact/Purpose:
The primary study objectives are:
1.To quantify personal exposures and indoor air concentrations for PM/gases for potentially sensitive individuals (cross sectional, inter- and intrapersonal).
2.To describe (magnitude and variability) the relationships between personal exposure, and indoor, outdoor and ambient air concentrations for PM/gases for different sensitive cohorts. These cohorts represent subjects of opportunity and relationships established will not be used to extrapolate to the general population.
3.To examine the inter- and intrapersonal variability in the relationship between personal exposures, and indoor, outdoor, and ambient air concentrations for PM/gases for sensitive individuals.
4.To identify and model the factors that contribute to the inter- and intrapersonal variability in the relationships between personal exposures and indoor, outdoor, and ambient air concentrations for PM/gases.
5.To determine the contribution of ambient concentrations to indoor air/personal exposures for PM/gases.
6.To examine the effects of air shed (location, season), population demographics, and residential setting (apartment vs stand-alone homes) on the relationship between personal exposure and indoor, outdoor, and ambient air concentrations for PM/gases.
Description:
Over 300 air change rate experiments were completed in two occupied residences: a two-story detached house in Redwood City, CA and a three-story townhouse in Reston, VA. A continuous monitor was used to measure the decay of sulfur hexafluoride tracer gas over periods of 1 to 18 hours. Each experiment included a measurement of the air change rate first with all exterior doors and windows closed (State 0), then with the single change from State 0 conditions of opening one or more windows. The overall average State 0 air change rate was 0.37 air changes per hour (h -1) (SD = 0.10 h -1; n = 112) for the California house and 0.41 h -1 (SD = 0.19 h -1; n = 203) for the Virginia house. Indoor-outdoor temperature differences appeared to be responsible for the variation at the Virginia house of 0.15 h -1 to 0.85 h -1 when windows were closed. Opening a single window increased the State 0 air change rate by an amount roughly proportional to the width of the opening, reaching increments as high as 0.80 h -1 in the California house and 1.3 h -1 in the Virginia house. Multiple window openings increased the air change rate by amounts ranging from 0.10 h -1 to 2.8 h -1 in the California house and from 0.49 h -1 to 1.7 h -1 in the Virginia house. Compared to temperature differences and wind effects, opening windows produced the greatest increase in the air change rates measured in both homes. Results of this study indicate the importance of occupant window opening behavior on a home's air change rate and the consequent need to incorporate this factor when estimating human exposure to indoor air pollutants.
The EPA, through its Office of Research and Development, funded and managed part of the research described herein. It has been subjected to Agency review and approved for publication. Mention of trade names or commercial products does not constitute an endorsement or recommendation for use.