On the IAQ Characteristics of Child Care Centers in the Tropics Arising from Different Ventilation Strategies

The IAQ characteristics and the corresponding health symptoms and thermal sensation of the occupants of child care centers in Singapore under 3 different ventilation strategies are reported. The 3 child care centers studied were centrally air-conditioned and mechanically (ACMV) ventilated (Case A), naturally ventilated (Case B) and hybrid (natural and air-conditioning) ventilated (Case C). The temperature and relative humidity of the natural and hybrid ventilated centers were consistently higher than that of ACMV but there was no difference in the thermal sensation among the workers as determined from their subjective responses, indicating adaptive thermal behaviour. Ventilation rates were the highest in Case B followed by Case C and finally Case A. CO2 and bacteria concentrations related to occupant were highest in the ACMV center highlighting the inadequacies of low ventilation rates. High CO2 concentration (>1000ppm) was associated with flu-like symptoms with an odds ratio of 2.8 (p=0.14). High VOC levels were found in a naturally ventilated center probably from dominant indoor sources. The natural and hybrid ventilated centers were not capable of preventing outdoor CO and fungi ingress while in the center equipped with the ACMV system, the filters were capable of reducing the outdoor airborne fungi indoors.