Comparative study of the indoor air quality of naturally ventilated and air-conditioned bedrooms of residential buildings in Singapore

Indoor air quality (IAQ) measurements were carried out in 3 residential dwellings in Singapore to find out the indoor air quality (IAQ) of the bedrooms. It was found that when the subjects utilized air-conditioners while sleeping, there was a considerable build-up of carbon dioxide (CO2) (>1000 ppm) for all types of air-conditioners. These CO2 levels were substantial higher as compared to naturally ventilated bedrooms. A survey was also conducted to investigate whether occupants exhibited sick building syndrome (SBS) symptoms while sleeping in air-conditioned (AC) as well as naturally ventilated (NV) bedrooms. A comparison showed that almost all occupants who used air-conditioners while sleeping exhibited one or more SBS symptoms and these occupants usually displayed more SBS symptoms after using air-conditioning than when they utilized natural ventilation. The survey also revealed that the frequency and duration of usage of air conditioning has important impact on the exhibition of the SBS symptoms.