Urban Heat Island Effect and Sustainable Pavement Materials

Abstract

The urban environment witnesses a high urban heat island (UHI) impact where temperatures rise substantially compared to those in the rural surroundings. Such conditions negatively affect outdoor thermal comfort as well as building cooling energy demands. In this regard, pavement systems, such as asphalt, cover 40 percent of an urban area and have a low albedo value along with high thermal mass. Cooling strategies like the use of cool pavements can effectively decrease heat fluxes and lower the temperatures of surfaces. However, the inclusion of green spaces including trees is vital to increase their efficiency. The objectives of this paper are: (i) to explore the materials currently used for pavement construction; (ii) to examine the contribution of these resources to the UHI Effect; and (iii) to investigate materials and strategies that can mitigate the UHI effect. Findings indicate that reflective pavement technologies — often termed “cool pavements” — play a crucial role by maintaining cooler surface temperatures, generating lower ambient air temperatures, reducing air conditioning demand, and decreasing greenhouse gas emissions. Polymer-matrix solar reflective coatings (epoxy and acrylic) and Phase-Change Materials (PCMs) represent the most promising active-cooling technologies for next-generation urban pavements.