Cool roofs are roofing systems designed to reflect significant solar radiation, reducing heat absorption and subsequent cooling energy demands in buildings. This paper provides a comprehensive review of cool roof technologies, covering performance standards, material options, energy-saving potential, and hygrothermal considerations. The review examines provisions in current codes and standards, which specify minimum requirements for solar reflectance, thermal emittance, and solar reflectance index (SRI) values. These criteria often vary based on factors like roof slope, climate zone, and building type. Different cool roof materials are explored, including reflective paints and coatings that can be applied to existing roofs as cost-effective solutions. Several studies have demonstrated the energy performance benefits of cool roofs, showing significant reductions in cooling loads, indoor air temperatures, peak cooling demand, and overall cooling energy consumption compared to traditional roofs. However, hygrothermal performance must be evaluated, especially in cold climates, to optimize insulation levels and avoid moisture accumulation risks, as reduced heat absorption can alter moisture migration patterns within the building envelope. While cool roofs provide substantial energy savings in hot climates, further research is needed to validate modeling approaches against real-world studies, investigate the impact of seasonality and green spaces on cool roof efficacy and urban heat island mitigation, and explore energy-saving potential, moisture control, and condensation risks in cold and humid environments.

The building sector is crucial in keeping the environment healthy, mainly because of its energy and material usage. Roofs are one of the most important components to consider, as they not only shield the building from the elements but also have a big impact on the environment. The paper provides a state-of-the-art review of the life cycle assessment (LCA) application in the roofing industry. The review examines three main focus areas: (1) LCA of different roofing materials, (2) LCA of roofing systems, and (3) whole-building LCA. Key takeaways from the literature review demonstrate that there is significant variability in LCA methods and impact categories assessed across roofing studies. Only a few studies have explored the complete urban scale in LCA assessments of roofing components. Future research can include utilizing the potential of LCA at urban scales, which can offer a full understanding of the environmental impacts associated with roofing materials in urban settings.