Evaluation of the cooling performance of various heat-reflective cool pavement coatings for Urban Heat Island mitigation

Abstract This paper investigates the optimization of heat-reflective cool pavement coatings to address the critical Urban Heat Island (UHI) effect, which significantly increases energy consumption for urban cooling and adversely impacts thermal comfort and public health. With pavements constituting about 30% of urban surfaces, their role in amplifying UHI effects underscores the need for innovative solutions. This study evaluated the cooling effect of heat reflective coatings (HRC) using water-based and oil-based binders, such as Acrylic Emulsions and Epoxy Resins, with the addition of functional fillers and pigments, including Titanium oxide, Iron oxide, and Silicon oxide. The results showed that both waterborne (acrylic emulsion) and oil-based (epoxy resin) HRC significantly reduced pavement surface temperatures, achieving maximum cooling effects of up to 20°C. During nighttime cooling simulations, these coatings maintained lower average temperatures, demonstrating their effectiveness both day and night. Waterborne HRC exhibited a rougher surface texture, resulting in higher skid resistance compared to the smoother epoxy resin HRC, which poses a potential risk for skid resistance and requires anti-skid additives. However, waterborne HRC showed signs of cracking after 24 hours of drying, indicating lower durability. Incorporating SiO 2 maintained the cooling performance of epoxy resin HRCs while reducing glossiness, enhancing safety and efficacy. Conversely, SiO 2 reduced the cooling effect in acrylic emulsion HRCs, suggesting that their natural matte appearance is already optimal. While yellow and white HRCs have high cooling effects, they may not be suitable for all applications due to potential glare and aesthetic mismatches, particularly in architectural and heritage settings.