Experimental investigation on the hygrothermal behavior of a new multilayer building envelope integrating PCM with bio-based material

Abstract

Bio-based materials have strong hygrothermal behavior and phase change materials (PCMs) have high thermal inertia, but they have usually been studied separately in most research. In this paper, the hygrothermal behavior of a multilayer building envelope integrating hemp lime concrete (HLC) and PCM was investigated at experimental level. The envelope was flanked by a climate chamber and the laboratory ambient to imitate the outdoor and indoor environments, respectively. Four envelope configurations comprising a reference (without PCM) and three configurations with PCM (PCM placed on the outdoor and indoor side, in the middle of the envelope) were considered in order to study the effect of PCM and its position on the hygrothermal behavior of the envelope. The results showed that the PCM had a significant effect on the hygrothermal behavior of HLC, based on the high coupling between temperature and relative humidity. The characteristic time was considered to quantitatively evaluate temperature and relative humidity trends, and their value was increased with the participation of PCM. Moreover, PCM increased the heat store/release capacity linearly with its position. The closer the PCM was to the outdoor, the higher the heat store/release capacity and the lower the heating/cooling load from the envelope to the indoor environment. These phenomena were closely related to the PCM's temperature distribution and its corresponding specific heat capacity. Therefore, due to the envelope's thermal and hygric inertia on the indoor environment and the building's energy saving potential, it was recommended that the PCM be placed close to the outdoor side.