An experimental investigation of phase change material (PCM)-enhanced cavity walls with integrated windows in office buildings: Optimising energy savings

In this study, the optimal PCM position for energy-saving potential in multi-layered PCM wall buildings with windows has been investigated, focusing on moderating indoor temperatures and reducing heating and cooling loads. An experimental setup was constructed to measure the thermal behaviour of the PCM wall with a double-glazed window. The results indicated that the optimal PCM positions were in an arrange of 341 mm and 356 mm measured from the external surface of the wall through which the energy consumption for heating and cooling could be reduced by approximately 34–37% and yielded both a moderate PMV maximum value of 0.21 and a PPD value of 6.0%. As the PCM distance was increased from the outer wall layer to the inner wall layer, the heat transfer rate across the wall followed an exponentially decaying function combined with a sinusoidal component, influenced by a phase shift, amplitude modification, and a constant offset. This reduction in heat transfer was achieved through the PCM’s capacity to absorb and release latent heat, thereby stabilising indoor temperatures and reducing dependency on HVAC systems. These findings underscore the potential of PCM layers to contribute to the design of more energy-efficient and sustainable building and wall structures.