Durability and performance of opaque high-reflectance envelope systems: A systematic review

The demand for energy-efficient dwellings has led to various design solutions that improve the performance of building envelopes. High surface temperatures affect the durability of insulation systems and energy performance. Highly reflective coatings (cool materials) reduce surface temperatures and improve the durability of thermal insulation systems. Recent research evaluates the impact of these coatings and emphasises their thermal-energy performance and reflectivity, but weathering and soiling can reduce their effectiveness over time. This article summarises the durability assessment of highly reflective coatings for opaque building envelopes through a systematic review combined with a meta-analysis of publications on the ageing reflectance of different building coating systems. The discussion focused on the relationship between weathering phenomena, reflectance loss and degradation behaviour depending on the ageing test used. It was noted that many studies focus on the effect of reflectance on energy demand but do not address degradation phenomena in detail or specify measures to mitigate the loss of durability. There is also a need for more information on the correlation between the extent of degradation and different approaches, such as accelerated or long-term testing, to evaluate highly reflective building coatings. While most research focuses on highly reflective building envelopes in hot climates, this review highlights important future research areas. It also proposes a methodology that aims to fill research gaps and enable a comprehensive assessment of highly reflective coatings in building envelopes for sustainable urban development.