Thermal comfort and ventilation performance in an air-conditioned mosque in tropical climates of Malaysia

Mosques serve as pivotal hubs for Muslim worship, accommodating intermittent prayer sessions occurring five times daily. Comprehending the environmental dynamics within air-conditioned structures experiencing varying occupancy is imperative for informed design decisions. This study aims to analyse a Malaysian mosque's thermal conditions, including comfort temperatures and compliance with standards. It also seeks to assess indoor air quality by measuring CO2 concentrations and estimating ventilation performance. Field measurements spanned a week and encompassed various prayer times. A questionnaire-based adaptive thermal comfort survey was conducted after Friday prayer. Furthermore, ventilation performance was estimated using the transient mass balance and decay methods. It was found that the optimum comfort zone was within the range of 26.0-27.8 degrees C with a comfort temperature of 27.3 degrees C using Griffiths' method. The study observed air changes per hour (ACH) at 0.7 h(-1) during the build-up and 1.1 h(-1) during the decay phase. The results indicate that the set point temperature at about 20 degrees C did not contribute to thermal comfort during prayer time, and the air quality during long periods of prayer time was worse due to poor ventilation. Therefore, adjusting the temperature to a higher acceptable temperature and improving the ventilation as simulated is suggested.