Effect of indoor and outdoor CO2 concentrations on requirement of minimal outdoor air volume

Based on the change characteristics of the concentration of CO₂ in atmosphere and urban micro environment, points out that the calculation basis for standardized value of personal minimal outdoor air volume should be properly adjusted during the design of air conditioning system. Based on the classification range of indoor air CO₂ concentration, discusses the range of outdoor air volume by classification standards of indoor air quality (IAQ). Combined with occupant activity intensity in main rooms of buildings, calculates the minimal outdoor air volumes under different CO₂ concentration differences between indoor and outdoor air. Compares them with the index in the current HVAC code. The result shows that when smaller value of CO₂ concentration difference is taken for coarsely populated room and bigger value is taken for densely populated room, the corresponding outdoor air volume range conforms to that in the current HVAC code.