Evaluating the microclimatic and thermal comfort impact of high-reflective pavements across different urban canyon settings in a tropical city

Source abstract

Urban heat islands (UHIs) pose major challenges in tropical cities, where elevated temperatures intensify thermal discomfort and environmental stress. The effectiveness of mitigation strategies, however, depends strongly on urban morphology. This study investigates how contrasting urban canyon configurations influence the microclimatic performance of reflective pavements (RP) and pedestrian thermal comfort in a tropical city. Representative vertical and horizontal urban canyons, characterized by distinct socioeconomic conditions and urban forms, were evaluated using high-resolution ENVI-met simulations under baseline and RP scenarios. Results showed that high-albedo pavements (α = 0.5) reduced surface temperatures by up to 9.6°C and air temperatures by 1.7°C during peak solar hours, but simultaneously increased mean radiant temperature by approximately 13°C. The cooling efficiency of reflective pavements was not uniform and depended critically on urban canyon geometry. Low-rise urban canyons exhibited higher temperatures than verticalized areas due to limited shading and restricted airflow. In contrast, vertical canyons reduced the overall effectiveness of RP through radiative trapping and multiple reflections. Furthermore, the conventional UTCI classification tended to overestimate thermal stress, whereas locally adapted UTCI thresholds provided a more realistic assessment consistent with residents’ thermal perception. These findings demonstrate that urban form plays a decisive role in modulating the benefits and trade-offs of reflective pavements and highlights the importance of context-sensitive UHI mitigation strategies for tropical cities.