Experimental assessment of ceiling cooling systems incorporating PCM in flat and domed roofs: Energy, environmental, and economic performance in hot-dry climates

This study experimentally assesses the cooling performance of phase change material (PCM)-integrated ceiling systems in two roof configurations—flat and domed—under the hot-dry climate of Yazd, Iran. The objective is to evaluate the thermal, economic, and environmental benefits of PCM-based ceiling systems compared to conventional systems. A ¼-scale building model was used to examine three configurations: a basic PCM ceiling, a fan-assisted PCM ceiling (PCM-F), and a mini cooler-assisted PCM ceiling (PCM-C), in both flat and domed roof setups. Comparative analysis shows that PCM integration reduces average indoor air temperature by up to 4 °C in the flat roof and 5 °C in the domed roof. The PCM-C configuration achieves the most effective cooling and thermal comfort, particularly with the domed roof, due to improved air circulation. Relative humidity remained largely unchanged in the PCM and PCM-F scenarios but increased by 6–8 % in the PCM-C configuration. Economic analysis over a 30-year period indicates that PCM-F offers the lowest total cost, with the domed roof reducing operating costs by up to 10 % compared to the flat roof. Environmental impact analysis reveals that PCM systems lower CO₂ emissions by up to 53 %, with domed roofs performing slightly better than the flat one. The findings suggest that PCM-integrated domed ceiling system, especially when combined with auxiliary cooling, offers a promising strategy for passive cooling and energy savings in hot-dry climates.