Effect of demand-controlled ventilation strategies on indoor air pollutants in a classroom: A Norwegian case study

Abstract

Abstract The choice of the minimum ventilation rate (V min ) in a demand-controlled ventilation strategy can influence energy demand but also introduce outdoor air pollutants. The latter may have direct health effects, as well as affect indoor chemical reactions. In this paper, we evaluate the effect of ventilation rates and operation hours on the level of CO 2 , nitrogen dioxide (NO 2 ), and ozone (O 3 ) in a classroom during normal use. We compared the baseline ventilation scenario (S0) with a V min of 430 m 3 /h with S1; V min of 150 m 3 /h for normal ventilation operation time (6:30-17:00) and continuous ventilation for 24h (S2). We found that S1 with reduced V min would lower the ozone concentration by 35% during the hours before occupancy compared to S0. Moreover, continuous ventilation during night time with a low V min resulted in almost as high O 3 concentrations as the baseline ventilation scenario. As O 3 reacts easily with certain VOCs to produce secondary organic aerosols, the level of V min and the ventilation duration would impact the indoor air quality upon entering the classroom.