Improving thermal comfort in mosques of hot-humid climates through passive and low- energy design strategies

Mosques have intermittent operational schedules with short-term occupancy during the five daily prayers. The occupancy level of the daily prayers is a fraction compared to the mandatory Friday prayers with full occupancy. Usually, the same thermal control mechanism is operated within the same large prayer hall to maintain the thermal comfort of the occupants. Yet, the comfort requirements are often not met due to the short span of operation during prayer times. Nevertheless, mosques have a very high energy usage as the same energy-intensive system is operated even during minimal occupancy profiles. The current research aims at using a passive approach towards design to achieve the comfort conditions during the low occupancy daily prayer times without employing mechanical intervention. Numerical simulations are carried out on a validated model of the case study building to investigate the impact of the west-facing Qiblah wall as the congregation stands in proximity to this wall. The design alternatives are tested in conjunction with ventilation strategies to holistically assess the thermal comfort of the occupants. Results show that as much as 4-6 degrees C reduction in indoor wall surface temperature can be achieved with a suitable Qiblah wall design, which reduces the mean radiant temperature of the occupants by 2-4 degrees C. Combined with ventilation strate-gies, thermal comfort can be significantly improved by at least 40% for the prayers during the hottest times of the day, and as much as 80% for night-time prayers. Results suggest that suit-able comfort conditions can be achieved without the need for air-conditioning for at least two or three of the five daily prayers.