Finite element and genetic algorithm-based optimization of phase change material integration for passive thermal regulation in studio apartments in Portugal

This study presents a finite element modelling (FEM) and genetic algorithm (GA)-based optimization framework for integrating phase change materials (PCM) into studio apartments to improve passive thermal regulation. A “T0 flat” in Coimbra, Portugal, was analysed to assess the influence of PCM placement, thickness, and melting temperature on indoor temperature stability and energy efficiency. The aim is to develop a validated optimization strategy that reduces reliance on active cooling in compact residential buildings. A high-fidelity FEM model was created to simulate transient heat transfer, incorporating real climate data and building envelope properties. Validation against measured electricity consumption from August 2024 showed strong alignment with real-world cooling demand. A GA was applied to optimize PCM configuration by systematically varying placement locations, material thickness, and melting temperature. Results indicate that optimal PCM integration can reduce peak indoor temperatures by up to 3.2 °C and cooling energy demand by 25.7 %. Among tested materials, salt hydrate (melting at 24 °C) demonstrated the highest latent heat storage, while a multi-layer PCM system (melting at 22 °C, 26 °C, and 30 °C) provided enhanced temperature buffering. Wall and ceiling integration proved more effective than floor applications due to higher exposure to solar gains and convection. The novelty of this study lies in combining validated FEM with GA to optimize PCM deployment across these critical variables in small urban dwellings—an area underexplored in prior research. The proposed framework offers a scalable, data-driven approach to enhancing building energy efficiency and supports climate-responsive design strategies in Mediterranean climates. • Numerical model and optimization enhanced passive building heat control. • Simulated energy use closely matched real apartment electricity data. • Multi-layer design lowered peak indoor temperature by up to 3.2 °C. • Wall and ceiling placement proved most effective for heat mitigation. • Optimization improved comfort with minimal material and energy use.