Experimental study on the thermal performance of PCM-based panels developed for exterior finishes of building walls

Phase change materials (PCM) can improve the thermal performance of building envelopes. Although they are commonly applied close to the indoor environment, a few studies reported their better performance on the envelope's exterior. The exterior PCM increases the envelope's thermal resistance to the outdoor environment, which can be favorable for warm and hot climatic conditions. However, studies that address PCM exterior applications are limited, and most of them were performed as part of numerical optimization for the PCM position. This study aims to experimentally investigate the thermal performance of PCM-based panels developed for walls' exterior finishes. Multiple panels were produced by incorporating the microencapsulated PCM into a cement render and foamed concrete. The panels were subject to consecutive heating and cooling cycles using a self-designed testing setup to evaluate their thermal performance compared to panels without PCM. The PCM-based panels showed effective reductions in the internal surface temperature and heat flux during the PCM melting process reached up to 7.35 °C and 58 W/m², respectively, which lowered their peaks by 3.95 °C and 26 W/m². As a consequence, the air temperature in the testing cell was decreased by 3.59 °C during the PCM melting time, resulting in lower peaks by 3.05 °C and lower temperatures exceeding 30 °C by 22%. Furthermore, the decrement factor of the testing cell with PCM-based panels was reduced to 0.64. The findings demonstrate the high effectiveness of PCM exterior applications. The panels produced from PCM and foamed concrete showed better thermal performance, indicating a promising solution to improve the thermal resistance of building walls.