Optimization study for PCM application in residential buildings under desert climatic conditions

Despite their effectiveness in improving indoor thermal conditions and reducing energy consumption, the performance of phase change materials (PCMs) in buildings is highly dependent on ambient conditions. In desert climates, where summer outdoor temperatures can exceed 40 °C and nighttime temperatures rarely drop below 30 °C, PCM application can be challenging and may lead to undesirable outcomes if not implemented properly. Therefore, an optimization study was conducted to assess the feasibility of using PCMs to enhance thermal performance and reduce the energy consumption of residential buildings in desert climates. The optimization was performed for different seasons and involved PCM's position and transition temperatures, cooling and heating setpoints, and combining mechanical ventilation for cooling. The results indicated that optimization based on summer conditions resulted in the most significant reduction in annual energy consumption (AEC), given the greater demand for cooling energy. The optimum performance was achieved with a cooling setpoint of 25–26 °C, PCM transition temperatures of 30–31 °C for externally applied PCM, 28 °C for internally applied PCM on external walls, and 24–26 °C for internal partitions. Under the investigated conditions, using the optimal PCMs for the cooling setpoints 25 °C and 26 °C achieved maximum AEC reduction of 24.1 % and 30.4 %, respectively, while the annual thermal discomfort (ATD) was 3 % and 30.5 %, respectively. Despite the higher ATD with the optimal PCM based on the cooling setpoint of 26 °C, 96 % of the operative temperature was maintained below 27 °C, indicating an acceptable thermal condition. The findings confirm that optimal PCMs can perform well in desert climates in reducing energy consumption and improving indoor thermal conditions.