Nature-based solutions for urban heat mitigation in historical and cultural block: The case of Beijing Old City

Abstract

Urban heat island can exacerbate the harmful influence on human health and urban environment in historical and cultural block within Beijing Old City, China. To improve urban resilience and human well-being, protect historical and cultural heritage, nature-based solutions for urban heat mitigation are being the hotspot of research. However, only few studies focused on the comprehensive thermal environment of historical and cultural block from the social, ecological and technical aspects. Thus, we set-up scenarios combining with the three domains, to explore the cooling effect and thermal comfort improvement of Dashilar Block through ENVI-met. The results showed that 1) The areas with highest air temperature (Ta) and physiological equivalent temperature (PET) were mainly distributed in Peizhi Hutong and Zongshu Toutiao. 2) Five mitigation scenarios adapting to historical protection requirements and public preferences were vertical greening, traditional greening, quality improvement greening, high-albedo paving, and comprehensive. 3) The comprehensive and vertical greening scenarios could reduce the mean Ta of whole block by 1.01 °C or 0.38 °C, decrease the percentage of Ta hotter zone by 13.87% or 19.63%, and reduce the local Ta inside the block by 0.65°C–1.80 °C or 0.33°C–1.05 °C, respectively, which turned out the cooling effect and thermal comfort improvement of abovementioned two scenarios could significantly alleviate the heat stress. The comprehensive and vertical greening can act as the preferred nature-based solution for heat mitigation in Dashilar Block. We believed that this study would provide novel insights into the balance between urban heat mitigation and heritage protection during the renewal of Beijing Old City.