A CO2-controlled ventilation system

For buildings in which the emissions from people is the main source of pollution, the number of people is the limiting factor for air ventilation. When such buildings are not used at full capacity, the ventilation, and consequently the energy consumption, is unnecessarily high. One possible control system would allow the amount of CO//2 in the exhaust air to control the ventilation rate. To study if this principle is practicable and economic, a CO//2 indicator has been installed in an office building in Helsinki. The mixture of exterior air and recirculated air is adjusted so that the amount of CO//2 during working hours is kept on 700 ppm. The equipment was used during winter 1981-82, and the variation of CO//2 and the exterior air flow has been registered. The proportion of other pollutants in the room air has been studied simultaneously with a gas chromatography. Different types of CO//2 indicators were used to study the efficiency of the control system.