Durability of high reflective materials designed for building envelopes

Abstract

As an alternative to mitigate the urban heat island effect, materials known as “cool surfaces” are a suitable passive technology for reducing heat transmittance into buildings and diminishing the electricity demand for cooling. However, due to ageing, the performance of cool surfaces becomes less effective, with decreasing solar reflectance generated by dust accumulation and microbial growth. However, there is little literature on the subject and the data usually present a local perspective in durability which makes harder to compare with other cases. This research conducted a systematic review on works approaching natural ageing of highly reflective materials to identify the main factors that influence the albedo durability of cool surfaces. The main factors found were macroclimate, microclimate, the tilt of exposure, materials characteristics, and substrate. The data analyses conducted in this research highlight the importance of having a general perspective when studying reflectance durability, since agents that don’t seem relevant when evaluating a local case can be important when comparing the general figure. The inspection promoted by this study might help future research to better analyse their results and connect the diffuse knowledge in the current state of the art.