Air change rates at night in northeast Chinese homes

Air change rate data for dwellings in China are scarce. We carried out a study of ventilation rates in 399 homes in Tianjin and Cangzhou, China. Carbon dioxide concentration was continuously measured for 24 h in bedrooms and living rooms. The air change rate at night was calculated using a single zone mass balance model. In the whole home, the median air change rates during sleeping time for spring, summer, autumn and winter were 0.27 h−1, 1.11 h−1, 0.29 h−1, 0.30 h−1. In the child's bedroom with closed window and door, the median air change rates during sleeping time for spring, summer, autumn and winter were 0.25 h−1, 0.25 h−1, 0.30 h−1, 0.37 h−1. Air change rates in homes with open windows were significantly higher than those in homes with closed windows (p = 0.000).