Phase change materials and building envelope: An innovative solution for energy transition

The energy efficiency of buildings is a critical challenge in regions with harsh climates, where heating and cooling demands are steadily increasing. Among the most promising passive strategies, the integration of phase-change materials (PCMs) into building envelopes enables latent heat storage and release, thereby stabilizing indoor temperatures and reducing overall energy consumption. This study employs transient CFD simulations to propose and assess an innovative wall system incorporating two PCM layers arranged in parallel, specifically tailored to the semi-arid climate of Marrakesh. The novelty of this work lies in the simultaneous parametric analysis of three key design factors: PCM type, thickness, and spatial positioning within the wall. Results indicate that the PCM1 (29 °C) + PCM4 (16 °C) configuration delivers the best performance, reducing indoor temperature fluctuations by over 40 % and lowering annual energy demand by up to 24 % compared to a reference wall without PCMs. Temperature contour analyses revealed a more uniform thermal distribution, while viscosity field visualizations provided valuable insights into the progression of melting and solidification cycles. These findings underscore the strategic role of PCMs as an effective passive solution for enhancing energy efficiency and thermal comfort in hot, arid climates. The study establishes a reproducible and climate-responsive framework tailored to North African conditions, paving the way for the broader adoption of PCMs in sustainable building design.