Single and combined phase change materials: Their effect on seasonal transition period

Phase change materials (PCMs) are being used as thermal mass in buildings to conserve energy. In this research, the application of appropriate PCMs to reduce building energy consumption and operating time of mechanical equipment during spring and autumn transition period in hot arid climate is studied. The study was conducted in buildings with diurnal occupation pattern. The simulation results were compared against measurements obtained from a calorimeter that was constructed for this purpose. The results show that PCM 29°C and 5 air change natural ventilation rate reduce annual energy consumption by 15%. This means that while for 38 days in spring and 29 days in autumn, the mechanical equipment can be turned off. The thermal performance of PCM 25°C is very well in spring. The appropriate PCM is the one with combined phase change melting point of 29°C and 21°C PCMs, which reduces energy consumption and increases the seasonal transition period 8% more than that of the single PCM 29°C.