Ventilation  ducts are the use of natural air (called fresh air or fresh air) to  replace the indoor air to improve the indoor air quality. So how does it improve indoor air quality?

(1) to provide oxygen required for human breathing;

(2) dilute indoor contaminants or odor;

(3) to send the indoor process of pollutants;

(4) to remove the excess heat or moisture (hereinafter referred to as waste heat and residual humidity);

(5) to provide the necessary room for combustion of indoor combustion equipment.