Influencing factors of mechanical night ventilation for an office building in Harbin

In order to save operation energy for air-conditioning systems, the summer outdoor climate in Harbin was analyzed, and 3 typical days were chosen. Then the indoor thermal environment with mechanical night ventilation in an office building in Harbin was simulated. The influencing factors of night ventilation such as the air change rate, the ventilation period and the envelope were analyzed. Results show that, in the range of ventilation rates for a conventional air-conditioning system, indoor temperatures and mean radiant temperature of the envelope surface decrease quickly as the increase of air change rate and ventilation period, thus the effect of night ventilation is obvious. While the envelope surface temperature and air temperature of the heavyweight walls are almost the same as those of the lightweight walls because of the short night ventilation period.