The Real Life Efficiency of Gas Phase Filters Used in General Ventilation and their Influence on the Indoor Air Quality of an Office Building

Gas phase filters have been installed within the air handling unit of an HVAC system feeding 100 %fresh (outdoor) air to an office building. The filters efficiency for ozone (O3) and nitrogen oxides (NO2and NO) has been measured continuously over a one year period as function of time and outdoor airparameters (temperature, relative humidity). The results show that the filters efficiency varies alongtime and depends on temperature and relative humidity of air. It has also been shown that the use ofthis kind of filters improves the indoor air quality as the indoor / outdoor concentration ratio is lowerwith the use of the gas phase filters than without.