Hygrothermal analysis of external walls with hemp wool and phase change materials insulation in Mediterranean climate: A case study of Tetouan, Morocco

Abstract

Energy-efficient wall systems are vital for sustainable construction, especially in humid Mediterranean climates. This study assesses the thermal and hygrothermal performance of four double hollow brick wall assemblies incorporating various insulation materials: air gaps, hemp wool, and phase change materials (PCMs) combined with hemp wool. Simulations were conducted using WUFI Pro software to analyze heat and moisture transfer under the Mediterranean climate of Tetouan, Morocco. The results reveal that the configuration with PCM placed before hemp wool delivers optimal performance. This setup achieves a thermal transmittance (U-value) of 0.38 W/m²·K, representing a reduction of 47 % compared to regulatory maximum standards. This configuration also demonstrates effective moisture control, keeping the hemp wool moisture content below the critical threshold of 18 % throughout the entire simulation period, thus preventing condensation and mold growth. In contrast, the air gap configuration failed to meet thermal standards and showed increased risks of mold growth. The PCM placed after hemp wool, while achieving a favorable U-value (0.38 W/m²·K), led to significant condensation at the critical interfaces with hemp wool. The highest mold growth was recorded at the right interface near the indoor environment (1632 mm), compromising long-term hygrothermal stability. These findings emphasize the importance of optimizing PCM placement and highlight the synergistic effects of combining PCM with hemp wool to enhance energy efficiency and indoor comfort. This study underscores the potential of such sustainable insulation systems in reducing energy demand while ensuring hygrothermal stability in humid Mediterranean buildings.