Distribution of Air Change Rates in Residential Buildings in Beijing, China

Abstract

China has been facing rapidly growing energy use and severe outdoor air pollution, such as fine particles (PM2.5) and ozone (O3) in recent years. Ambient air could emigrate to indoor environments through openings of buildings, influencing the concentrations of indoor PM2.5, O3, and volatile organic compounds (VOCs) as well as the energy consumption to ensure satisfied indoor air quality. Therefore, air change rate is significantly important in estimating human exposure to air pollutants and energy consumption. In this study, the air change rates in residences without mechanical ventilation system in Beijing, China, when windows were closed and open, were measured. The influential factors were analyzed. The results show that the mean value of air infiltration rate (windows closed) and natural ventilation rate (windows open) for four seasons were 0.31 h−1 and 3.43 h−1, respectively. The air change rates when the windows were closed and open were log-normally distributed, with mean values of −1.77 and 0.76, and standard deviations of 1.02 and 0.88, respectively. Outdoor wind speed, number of floors, type of window, type of building, apartment volume, construction year, and number of rooms had a significant influence on the air infiltration rate. Outdoor air temperature and bedroom volume had a significant influence on the natural ventilation rate.