Associating thermal comfort and preference in Malaysian universities’ air-conditioned office rooms under various set-point temperatures

Overcooling indoor spaces in hot-and-humid regions indicate excessive usage of air conditioner (AC). Understanding the occupants' thermal perception in AC settings helps navigate the cooling energy required. This study investigated thermal comfort in biased and non-biased environments and examined the occupants’ preferences. Four set-point temperature conditions (Original, Original ±2 °C, and MS Standard) were implemented in a semi-controlled field study done in 19 offices. 628 samples were taken from 42 occupants via thermal measurements and questionnaire surveys. The indoor air temperature in the typical AC settings (Original set-point) was 23.1 °C, denoting non-compliance to the local guideline. The results showed that occupants generally felt more comfortable when the indoor air temperature was increased. The mean comfort temperature was 24.6 °C, and the proportion of comfort votes depletes when the operative temperature reaches 26 °C. The preferred temperature was estimated at 23.9 °C, and the linear relationship with comfort temperatures revealed that occupants preferred a cooler environment despite being thermally comfortable. The findings suggest that occupants could tolerate higher AC settings well, but thermal preference may be a critical factor in estimating the comfort temperature limits.