Performance evaluation of different building envelopes integrated with phase change materials in tropical climates

The need to improve building envelope components and reduce energy consumption is becoming increasingly crucial. The use of phase-change material (PCM) technologies is a viable solution to reduce energy consumption in buildings and associated greenhouse gas emissions. However, the performance of PCMs in buildings is strongly dependent on the melting temperatures and the climate conditions of the building's location. Therefore, the present study presents an optimisation-based approach to assessing the performance of building walls integrated with PCMs at different melting temperatures. To achieve this goal, a multiobjective genetic algorithm is used in conjunction with EnergyPlus building energy models to determine the optimal balance between total building energy consumption, lifecycle cost, and CO2 emissions. The proposed approach is applied to a single-family residential building located in six locations in the Central African sub-region classified as tropical savanna climate (Aw), hot semi-arid climate (Bsh), tropical rainforest climate (Af), and tropical monsoon climate (Am). Two different PCM technologies (InfiniteRPCM and BiocPCM) are applied to four wall types (brick, concrete block, cast concrete, and earth), and their parametric models are developed in EnergyPlus to optimise the melting temperature, thickness, and location of each PCM layer simultaneously. An optimisation is conducted for each selected wall and each location, and the optimised buildings are systematically compared to the reference buildings. The optimisation results showed that regardless of the climate zone and wall type, the application of PCMs with different melting temperatures significantly reduced energy consumption and CO2 emissions. Moreover, the results showed a different set of optimal solutions for each climate zone and wall type. The optimal solutions reduced the total energy, life cycle cost, and CO2 emissions by up to 47.80 %, 29.62 %, and 52.96 %, respectively.