Compromise between ventilation, filtration strategies and recirculation rates for the design and operation of air-conditioned facilities in the tropics

This study examines the impact of filtration, ventilation and recirculation rate on concentration of condensed-phase, ozone (of outdoor origin)-derived oxidation products (secondary organic aerosols (SOA)) in a model room with a ventilation system that recirculates a large percentage (90%) of its supply air. Additionally, it critically evaluates the potential approach for filtering recirculated air and also avoiding the negative consequence of having loaded filters in a ventilation system. Increased recirculation rate not only influences the surface removal rate constant, but also increases the fraction of pollutants removed by building filters. Increased ventilation rate dilutes pollutants with indoor sources and ozone-derived products. Activated carbon filters are more effective in reducing ozone and SOA particles than filters without carbon. Even a filter with a quarter of the standard carbon content of the commercially available bag-type stand-alone combination filter incorporating activated carbon improves the perceived air quality significantly more than a filter without carbon. This study is important because it provides information on how to improve the health and comfort of indoor environment inhabitants without compromising on energy conservation.