A national survey of window-opening behavior in United States homes.

Air exchange is among the most important building parameters influencing indoor air quality and energy use. Over 18-month period we surveyed over 3800 individuals to generate a contemporary, nationwide measure of window- and door-opening behavior. We also identified influences of demographics, climate, and region. For the entire survey, including all seasons and geographic regions, 43.9% of respondents said that at least one window was open the day prior to taking the survey. Greater window-opening frequency was associated with having a lower income, living in attached homes or apartments, renting, lack of air conditioning, or being Asian or Hispanic. People living in the west and north open windows considerably more frequently and longer than those in the southeastern US. Window-opening frequency and duration increases with outdoor temperature until a maximum occurs at 18-21°C. At temperatures greater than this, window frequency decreases. The pattern roughly holds, by region, with the peak occurring at a lower temperature in the NW (12°C), and a higher temperature in the SW and SE. The frequency of door opening is roughly half that of window opening with similar, but not identical, demographic, regional, and climate associations.

Analysis of indoor particles and gases and their evolution with natural ventilation.

The air composition and reactivity from outdoor and indoor mixing field campaign was conducted to investigate the impacts of natural ventilation (ie, window opening and closing) on indoor air quality. In this study, a thermal desorption aerosol gas chromatograph (TAG) obtained measurements of indoor particle- and gas-phase semi- and intermediately volatile organic compounds both inside and outside a single-family test home. Together with measurements from a suite of instruments, we use TAG data to evaluate changes in indoor particles and gases at three natural ventilation periods. Positive matrix factorization was performed on TAG and adsorbent tube data to explore five distinct chemical and physical processes occurring in the indoor environment. Outdoor-to-indoor transport is observed for sulfate, isoprene epoxydiols, polycyclic aromatic hydrocarbons, and heavy alkanes. Dilution of indoor species is observed for volatile, non-reactive species including methylcyclohexane and decamethylcyclopentasiloxane. Window opening drives enhanced emissions of semi- and intermediately volatile species including TXIB, DEET, diethyl phthalate, and carvone from indoor surfaces. Formation via enhanced oxidation was observed for nonanal and 2-decanone when outdoor oxidants entered the home. Finally, oxidative depletion of gas-phase terpenes (eg, limonene and α-pinene) was anticipated but not observed due to limited measurement resolution and dynamically changing conditions.