Multi-objective optimization of energy and thermal comfort using insulation and phase change materials in residential buildings

Recently, due to the increasing demand for energy and the identification of fossil fuels and their pollution, the focus on renewable energy is increasing day by day, so the use of renewable energy and energy-saving techniques is very important. PCMs are one of the most effective means of thermal energy storage, whose task is to change phase with increasing temperature, store thermal energy, and release this energy with decreasing temperature. This is one of the applications of these materials in building walls. In this research, the aim is to analyze and investigate the use of phase change materials in addition to thermal insulation. For this purpose, optimization in terms of energy and thermal comfort of residents has been done by the response surface method. Four Iranian cities with different climates—Tehran, Bandar Abbas, Tabriz, and Rasht—have undergone this optimization. According to the results, it can be concluded that the best temperature for the heating thermostat is approximately 20 °C and for the cooling thermostat, approximately 28 °C and 25 °C. Also, the best thermal insulation and PCMs are polyurethane and BioPCMDSCM27Q21. The thickness of the thermal insulation in the range between 6.9 cm and 9.8 cm is chosen as optimal, and the thickness of the phase change material is approximately 5 cm optimal for all cities (except Tehran). Due to the optimization of thermal comfort between 25 and 60 %, heating electricity between 43 and 99 % and cooling electricity between 38 and 52 % have been improved. •This study deals with the use of PCM and thermal insulation in Iran, focusing on energy optimization and thermal comfort.•The best temperature for the heating thermostat is 20 °C and for the cooling thermostat 28 °C and 25 °C.•The best thermal insulation and phase change materials are polyurethane and BioPCMDSCM27Q21.•The optimal thickness of thermal insulation was obtained from 6.9 cm to 9.8 cm for all cities.•Thermal comfort 25-60 %, heating electricity 45-100 % and cooling electricity 40-53 % have been improved.