Thermal Adaptive Behavior of Occupants in Air-conditioned Office Buildings in Thailand

Thermal adaptive behaviors are the actions people take to adjust to the indoor environment. This study aims to clarify occupants' perception of thermal environments and how they adapt themselves into those environments of air-conditioned offices in the tropical region. Six offices in Bangkok, Thailand, were investigated during April to September 2018. Indoor environment quality measuring devices were installed inside the offices to evaluate factors such as indoor temperature, humidity, and air velocity. Questionnaires following the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) 55 standard were distributed to occupants during working hours. Thermal comfort votes were analyzed together with behavioral adaptation votes. When we plotted thermal environment values on a psychrometric chart, they were inside 1.0 clo rather than 0.5 clo. Out of 2,028 samples, 50.2 % of occupants voted neutral. However, they felt colder than neutral rather than feeling warmer than neutral (36 %:14 %). Occupants who felt comfortable were 45% of total occupants, and 59.7% of them preferred "no change". Considering adaptive behavior, the highest activity was changing of clothes (50%). Those who wore more clothing (68.9 %) voted for feeling slightly cool to cold. Of those, 34% changed clothing during the day. The median of clothing increased from 0.56 clo to 0.61 clo to reduce the feeling-cold sensation and increase thermal neutrality. Other adaptive behaviors were drinking hot or cold water (31.3%), doing nothing (26.2%), moving around (24.5%), wearing a scarf (14.7%), using a pedestal fan (11.8%), taking a rest (8.6%), washing hands or face (8%), and opening or closing window blinds (7.7%). These adaptive behaviors were strongly relevant to thermal sensation votes and maintaining thermal comfort. These adaptive actions were adopted by both the feeling-hot persons and the feeling-cold persons. This study would be applicable to offices in Thailand in terms of both thermal satisfaction and human behavior.