Dynamic hygrothermal behavior and energy performance analysis of a novel multilayer building envelope based on PCM and hemp concrete

Phase change materials (PCMs) have high thermal inertia while hygroscopic materials have high hygric inertia. However, few studies have integrated the two materials and considered both hygrothermal behavior and energy performance. This study proposed a novel multilayer building envelope integrated by PCM and bio-based hygroscopic material (hemp concrete) to utilize the advantages of both materials. Four envelope configurations were experimental studied based on the presence and location of the PCM to study the effect of PCM and its location on the hygrothermal behavior and the energy performance of the integrated envelope. The results demonstrated the benefits of PCM in reducing the temperature/relative humidity (T/RH) amplitude and energy consumption as well as delaying the peak T of the envelope. Placement of the PCM in the middle of the envelope was recommended, with the PCM kept in a partially melted state. Compared to the configuration without PCM, the T/RH amplitude and energy consumption were reduced by 50%/60% and 15.3%, respectively, and the peak T was delayed by 70.4%. The PCM placed on the outdoor side had the highest efficiency and energy participation, but it absorbed the most heat and was prone to overmelting. The envelope with PCM placed on the indoor side lost the benefit of regulating RH. This study provides a reference for multilayer envelopes composed of PCMs and hygroscopic materials and dedicated to T/RH regulation.