Pervasive Building Height Thresholds for Urban Heat Response and Implications for Climate Mitigation

Abstract

Urbanization is accelerating vertical urban development, yet the complex relationship between building height (BH) and urban heat island (UHI) intensity remains underexplored. Using 30-m high-resolution urban building data from 2005 to 2020, we quantify the impact of BH on UHI across 11,290 urban grid cells in 331 Chinese prefecture-level cities and assess the potential for UHI mitigation through BH composition reorganization. Our analysis reveals a critical BH threshold (BH_crit) that marks a shift in the thermal effect of BH. Below BH_crit, increasing BH intensifies UHI effects; beyond this threshold, further height increases result in cooling—a finding that challenges the conventional assumption that taller buildings consistently exacerbate urban heat. We further project that, in principle, China's urban grid cells could reduce UHI intensity through BH reorganization, with a national average mitigation potential of 0.31 ± 0.004°C. These findings underscore the importance of optimizing vertical urban composition as a proactive UHI mitigation strategy and provide valuable insights for sustainable urban densification from a three-dimensional perspective.