Multiobjective passive optimization of building envelopes integrated phase change material in tropical climate: A case of Gabon

Energy consumption in buildings has increased significantly in recent years, with the building envelope playing a key role. Passive systems incorporating phase-change materials (PCMs) offer an effective approach to improving energy efficiency and reducing occupants’ thermal discomfort. This study presents an optimization-based method to evaluate the energy and thermal performance of building walls integrating PCMs with different melting temperatures. The approach is applied to a single residential building located in two major cities of Gabon, considering two envelope types: concrete block and earth block walls. Annual energy consumption is used to assess energy efficiency improvements, while thermal performance is evaluated using average temperature reduction (ATR), maximum temperature reduction (MTR), and discomfort hours (DH). The results show that PCM integration provides balanced performance across both envelope types and climate zones. Energy consumption is reduced by 29.11% and 31.50% in Libreville and by 27.14% and 30.05% in Port-Gentil for concrete and earth block walls, respectively, leading to cost savings of 23.61% and 27.75% in Libreville and 21.86% and 25.66% in Port-Gentil. In terms of thermal comfort, discomfort hours decrease by up to 68.09% in Libreville and 64.81% in Port-Gentil. Average indoor temperature variations are reduced by up to 1.11°C in Libreville and 1.55°C in Port-Gentil, while maximum indoor temperatures decrease by up to 2.91°C and 3.31°C in Libreville and Port-Gentil, respectively