Numerical analysis on the energy performance of the PCMs-integrated thermochromic coating building envelopes

Abstract

Extreme environmental conditions are inappropriate for the cycling of phase change materials (PCMs) attached to building envelopes and have a negative impact on their energy performance. To solve this problem, therefore, thermochromic (TC) coatings are proposed to improve the energy efficiency of PCMs by regulating solar radiation influence. In this paper, the energy performance analysis of TC-PCM systems was carried out in five different representative climate zones. Simulation findings show that, compared to traditional PCM systems (TR-PCM), in the climate characteristics of Shanghai, the annual energy demand of TC-PCM systems decreases by 42.9 kWh/m2, and the corresponding energy-saving rate is high up to 39.9%. This is because the adaptive solar absorptance of TC-PCM systems could enhance the phase change cycle performance of PCMs to reduce both the cooling and heating energy demand. The results also show that the TC-PCM system, with a switching temperature of 26 °C for TC coatings and a transition temperature of 26 °C for PCMs, could achieve the lowest annual energy demand in the climate characteristics of Shanghai. Finally, we investigated that the TC-PCM system has huge potential for energy-savings in all provinces in hot summer and cold winter climate zones, and the highest energy-savings rate can be as high as 10.2%.