Thermal performance and solar absorptance of asbestos-free fiber cement roof tiles under different natural aging processes

Abstract Fiber cement roof tiles undergo natural aging processes that may change their surface solar absorptance and thermal performance: carbonation, efflorescence and fungal development. With the aim of identifying the impact of these processes on their absorptance and thermal performance, this research study was undertaken in three stages: a) determination of the aging processes in tiles naturally aged for 28 days and after 36 months of exposure; b) surface temperature measurements by infrared thermography; and c) spectral reflectance measurements with a spectrophotometer to calculate the solar absorptance of the tiles. The results indicate that the carbonation process after 36 months of natural aging reduced the tiles' absorptance and surface temperatures when compared to the new 28 days' tiles. However, tiles with fungal growth after 36 months of exposure showed increased initial absorptance and surface temperatures, indicating that fungal growth can increase building solar heat gains. The results indicated that the natural aging processes of fiber cement tiles considerably affect its thermal performance over the building's lifetime.