Abstract:A calculation method for night ventilation was presented by considering the air flow rate as piecewise function and utilizing the calculation method of natural ventilation. A night ventilation experiment was done to compare the effect of ventilation time and air flow rate, and the temperature of experimented rooms was calculated by the model. The results of experimental and mathematical calculations were compared. It has been shown that they are in good agreement, so the calculation method on night ventilation can be used in engineering.