Thermal Comfort Evaluation and Building Heat Gain Assessment of Naturally Ventilated Public-School Classrooms in Rodriguez, Rizal: Basis for Thermal Comfort Intervention

This study aimed to examine the indoor thermal environmental conditions and their relationship to the thermal comfort of occupants in a naturally ventilated public-school building in Rodriguez, Rizal, Philippines during the dry season. Indoor environmental parameters such as air temperature, humidity, etc., and mean radiant temperature were monitored at various floors of the building at three-hour intervals during the day. Thermal sensation votes of approximately 30 students per classroom using ASHRAE 55 survey were also recorded The findings revealed significant vertical and temporal variations in indoor environmental conditions within the building. Higher floor levels consistently recorded higher environmental parameter compared with lower floors which indicates the influence of solar heat gain through the building envelope. Thermal sensation responses of students also reflected increasing levels of thermal discomfort during midday and afternoon periods when indoor temperatures were highest. Statistical analyses using Pearson correlation demonstrated strong relationships between thermal comfort responses and measured environmental variables, particularly mean radiant temperature and operative temperature. Repeated measures of ANOVA confirmed significant differences in thermal conditions among floor levels and across different periods of the day. The results highlight the substantial role of building heat gain and ventilation limitations in influencing indoor thermal comfort in naturally ventilated DepEd classrooms located in tropical climates. It also emphasizes the significance of the use of passive and active design strategies such as cross-ventilation, reflective paint, exhaust fans, and solar-powered whirlybirds to reduce heat stress in classrooms. Recommendations have been made to monitor the peak heat periods and limit the occupancy of classrooms when the thermal conditions exceed the safe comfort thresholds.