Experimental evaluation of the impact of roofing materials and natural ventilation on attic overheating in a temperate Chilean climate

Journal article, 2026

This study presents an experimental evaluation of overheating in habitable attics, examining the combined impact of roofing material and natural ventilation in a temperate climate. 1:5 scale test cells were built in Concepción, Chile (Csb), representative of lightweight housing construction. Asphalt-shingle and Aluzinc (high-reflectance) roofs were compared under two conditions: closed windows and cross-ventilation. Indoor air temperatures were monitored for 15 days in summer and 15 days in winter. Quantitative analysis was carried out using a representative average day for each measurement period. In summer, the test cell with the asphalt-shingle roof reached a maximum temperature of 32.71°C, exceeding that of the Aluzinc test cell by 2.84 K, and exhibited a thermal lag of 2–3 h, maintaining elevated indoor temperatures during the afternoon and delaying night-time cooling. In winter, the differences between materials were considerably smaller (0.84 K), indicating a limited thermal penalty of high-reflectance roofs under low solar radiation. The results confirm that high-reflectance roofs combined with natural ventilation constitute an effective passive strategy for mitigating overheating in habitable attics. This study broadens the regional empirical evidence and highlights overheating as an emerging challenge in temperate climates.