presents the air-pollutionadjusted NV hours with box plot at five climate zones in the year of 2015. The national average NV hours is 2324 (out of 8760 h/year), with a standard deviation of 778. Clear differences in NV hour are observed across five climate zones. The Mild climate zone includes cities with the most NV hours. It is the most favorable climate for utilizing natural ventilation mainly due to the suitable outdoor temperature throughout the year. On the other hand, Hot Summer/Cold Winter (HSCW) is the least favorable climate for natural ventilation due the long hot/humid summers and cold/humid winters.