Determining the optimal location and thickness of phase change materials in the building walls: an energy-economic analysis

One of the most important approaches for energy consumption reduction in buildings is employing thermal insulation. Phase change materials (PCM) can be used in many insulation applications due to their high heat capacity, low heat transfer coefficient and energy storage potential. In this study, the numerical simulation is used to investigate the effect of employing PCM as thermal insulation in the educational building of Hakim Sabzevari University located in Iran during the six hot months of the year. For this purpose, the optimal location of PCM layer into the wall is firstly determined, and then, different PCM thicknesses of 2, 3, 4 and 5 cm are examined. It is found that the ratio of heat exchange reduction using PCM layer with thicknesses of 2, 3, 4 and 5 cm is equal to 9.8%, 13.4%, 17.5% and 20.4%, respectively. Finally, the amount of energy saving and payback period for different thicknesses of PCM are calculated based on thermo-economic analysis. Accordingly, an optimal PCM thickness of 3 cm is obtained using Pareto solutions and TOPSIS method which leads to a payback period of 50 months.