Determining the most efficient phase change materials configuration for enhancing the thermal and energy performance of concrete building envelopes in a tropical region

Retrofit techniques applying phase change materials (PCM) to existing building envelopes can passively decrease solar heat gains in indoor environments. To assess the application potential of PCM in building fabrics, two identical concrete test cells were constructed. Concrete represents the main construction materials used in Mauritian buildings. The SP25E2 PCM was selected for the experimental study as preliminary analysis indicated that the average indoor temperature closely matches the SP25E2 PCM's melting temperature of 25 degrees C. A wooden structure was used inside the PCM test cell for easy incorporation and reconfiguration of multiple layers of PCM panels on the building envelopes. Weather data and indoor temperatures were gathered during both winter and summer periods. Multiple linear regression analysis was then used to determine the PCM configuration with the best thermal efficiency based on a new metric indicator for indoor thermal comfort. The experimental results show that installing two PCM layers under the roof and on the north oriented fa & ccedil;ade, respectively, and using a single PCM layer on the east and west fa & ccedil;ade each, represents the most efficient strategy. The regression analysis also demonstrates that night ventilation further improves the thermal efficiency of this PCM configuration. Finally, the CO2 emission and electricity cost savings calculations revealed that the most efficient configuration led to a reduction of 2.91 kg CO2 and $0.38 per day, respectively, while the least efficient configuration showed only a reduction of 1.30 kg CO2 and $0.17 per day, respectively. These values demonstrate that maximising the potential of PCM in building envelopes through well-thought building designs can double the savings of both the CO2 emission and the electricity costs compared to an improperly planned strategy.