Experimental study of the thermal protection performance of the high reflectivity-phase change material (PCM) roof in summer

In order to reduce the building heat gain through the roof, a new kind of high reflectivity-PCM roof was proposed. That is to lay a layer of PCM outside the common roof, then a layer of high reflectivity film was laid outside the PCM layer. To compare the thermal protection performance of the high reflectivity-PCM roof with PCM roof, high reflectivity roof and common roof, three real size rooms were built. The three rooms were first installed with PCM roof, reflectivity roof and common roof. The thermal protection performance of the three roofs was compared for eight days (July 23rd to July 30th). Then the PCM roof and the high reflectivity roof were combined to form the high reflectivity-PCM roof, and the thermal protection performance of the high reflectivity-PCM roof was also compared to that of common roof for another eight days (Aug. 17th to Aug. 24th). Results showed that the high reflectivity-PCM roof performed more excellent in decreasing indoor air temperature, inner surface temperature and inner surface heat flux. Thermal balance results showed that the new type of roof can significantly reduce the solar radiation heat gain and storage most part of the heat passing through the high reflectivity film. The high reflectivity-PCM roof had better thermal protection performance than the other three roofs.