Analysing the relationship between urban form and urban heat island effect at a city-block scale

Abstract

Over the last twenty years China has witnessed rapid urbanisation process. The modification of urban land surface due to urbanisation changes not only affects the geometry of an urban settlement but also its thermal properties, which may give rise to the urban heat island (UHI) affect. Although there has been a large amount of research on mitigation strategies of UHI at the urban scale, there is still a lack of research that concerns the influence of urban geometrical settlement on UHI at a city block scale. Chengdu, a megacity in south-west China, has been chosen as the research subject in this study, to identify the existence of the UHI phenomenon, to measure its magnitude, and to investigate the relationship between UHI and urban design variables, including Floor Area Ratio, Building Coverage Ratio, Green Coverage Ratio, Building Height, Plot-layout Form, and Project Type (function). In this study, urban maps of UHI had been derived from MODIS satellite data for 103 selected projects and 28 urban zones. Correlations were carried out between UHI intensity and urban design variables. The study has developed design guidelines for improving outdoor thermal performance at an city block level. Moreover, a new approach to observe UHI at multi-scales in a long-time period had been conducted, providing a new method to analysis UHI at a city-block scale.