Numerical analysis of the thermal performance of a lightweight insulating roof integrated with a phase change material

Lightweight roofing materials are increasingly adopted due to their low structural load, ease of installation, and high energy efficiency. The present study numerically investigated the thermal behavior of two typical lightweight roof systems used in Mexico incorporating an inorganic PCM under warm-subhumid climatic conditions. A two-dimensional transient conjugate heat transfer analysis was conducted using the open-source code OpenFoam. Based on this model, four roof configurations were evaluated through computational fluid dynamics, considering two base materials, namely concrete and expanded polystyrene (EPS), with and without PCM integration. Notably, lightweight roofs incorporating the PCM reduced indoor heat gain, delayed peak temperatures, and stabilized interior conditions, leading to energy savings of up to 86.5 % (EPS–PCM configuration). These findings underscore the potential of PCM-based solutions to improve cooling demand in hot climates, offering a cost-effective solution for environmentally friendly building design.