The effects of ventilation operations in determining contributions of VOCs sources in air-conditioned tropical buildings

This study analyses the findings of volatile organic compounds (VOCs) levels found in two tropical office buildings (a 1 year old and a 6 year old building) under different conditions of ventilation operations. The geometric concentrations of 11 target VOCs and TVOC have been measured under two scenarios—(1) normal occupancy with ventilation system operating and (2) when the ventilation system has completely shut down. Under the first scenario, the VOCs emission rate determined through mass balanced modeling is due to the buildings, occupants and their activities and ventilation systems. The emission from the second scenario is purely due to the building materials. Majority of the VOCs rose in concentrations after the ventilation system has shut down with exceptions for benzene, benzaldehyde and tridecane that are attributable to outdoor and occupant related activities and ventilation systems. The indoor–outdoor (I/O) ratio method of determining source contributions has been found to be a crude method for this case study. Instead, utilizing the ventilation-resolved mass balanced model method to evaluate contributions of sources (SER) from outdoors, building materials, occupants, their activities and ventilation systems have yielded relatively good and accurate results.