REDEFINING APPROPRIATE THERMAL COMFORT STANDARD FOR NATURALLY VENTILATED BUILDINGS IN TROPICS (SINGAPORE AND INDONESIA PERSPECTIVE)

In naturally ventilated buildings (NVB) located in tropical regions, thermal comfort prediction based on PMV standard has shown some deviation from observed results. Hot and humid environmental conditions throughout the year and personal adaptation make the people in tropics expect and perceive thermal comfort differently. The proposed thermal comfort standard based on adaptive modeling approach is still not convincing enough for application since it sometimes rely on one environmental parameter for prediction. This study has collected more than 1000 data through extensive field survey in Singapore and Indonesia. The potential of combining the fundamental thermoregulation with the adaptive approach that considers behavioral adaptation has been explored. The reciprocal effects from environmental parameters and occupant’s behavioral adaptation were investigated. In tropical free running buildings where the air temperature and humidity can not be modified without mechanical means, the people were observed to prefer substantially higher wind speed. INDEX TERMS Adaptive behavior, Thermal comfort, Tropical climate INTRODUCTION In the past twenty years, the percentage of household in Singapore which installed AirConditioner (AC) unit, has increased significantly from only 7.8 % in 1978 to 57.7% in 1998 (Singstat 2000). The increment of AC availability more than seven times indicates an interesting phenomenon of how a higher standard of living requires a better comfortability in living environment. To do so, the occupants actually play active roles in ensuring their living environment is as comfortable as possible. In comparison with other buildings such as offices, occupants in residential NVB have more freedom to control their environment in the form of clothing adjustments, taking bath more frequently, getting more drink, opening windows, switching on fan or AC etc (Wong NH et.al 2002). It is rather complicated to comprehend the whole mechanism of human thermal perception and control as well as to provide criteria for thermal comfort assessment in NVB. In some publications, it has been presented that it is unreasonable to apply directly thermal comfort standards developed for mechanically controlled (AC) buildings to NVB (Fountain et.al 1996, Brager et.al 2000). Firstly, this inapplicability is due to large differences in environmental controllability. For example, in the tropics, uniformly high air temperature inside and outside spaces and constantly high humidity cannot be modified easily by passive cooling strategies. Secondly, the inapplicability could be due to differential living context which is particularly important in the context of those countries where only a small percentage of buildings are * Contact author email: bdgwnh@nus.edu.sg Proceedings: Indoor Air 2002