Economic optimization of PCM and insulation layer thickness in residential buildings

As suggested by previous studies, in economic optimization of buildings equipped with phase change materials, insulation layer and PCM highly affect each other's performance. To consider these effects, in the present study, the thickness of the insulation and PCM layer of a residential building are optimized simultaneously. Coupled with EnergyPlus as the thermal simulation tool, genetic algorithm is applied to optimize the thicknesses for different climatic regions of Iran. Tehran, Isfahan, Shiraz, Bandar Abbas, Yazd, and Tabriz were selected for optimization. The fitness function is the total cost of the building throughout its operation years. In each city, the optimum PCM and insulation layer thicknesses are obtained with different present worth factors each accounting for a different scenario regarding the economic outlook of the country. Results show that the optimum PCM thickness is zero for all cases. On the other hand, the optimum insulation thickness varies significantly by region and PWF. While in southern parts of the country it was approximately zero, in cold regions, the optimum thickness was more than 6 cm. Moreover, results show that with current economic situation of the country, insulation layers are far more cost effective than phase change materials.