Investigation of typical residential block typologies and their impact on pedestrian-level microclimate in summers in Nanjing, China

Abstract

The morphology of urban residential blocks in China, which is strictly affected by regulations, can potentially improve or deteriorate microclimates. This paper first proposes a framework for identifying typical residential block typologies using Nanjing as an example. A thorough investigation, consisting of 114 samples, was conducted, and 18 typical residential block typologies were summarized. Second, 3D non-isothermal numerical simulations were performed on the hottest days of summer using the ENVI-met. The effect of morphological indices on the microclimate at the pedestrian level was explored using statistical methods and a novel graphic method named m-SpaceMate. The results revealed a strong correlation between the urban heat island intensity (UHII), mean radiation temperature, and universal thermal climate index (UTCI) and floor area ratio (FAR), as well as between wind velocity (U) and building coverage ratio (BCR). A significant increase in FAR (by approximately 1.0) can result in a low UTCI that was driven by MRT and shading conditions. Six-floor blocks, with FAR between 1.8 and 2.1, had a better overall thermal environment (except for lower U) than that of 11-floor blocks. When considering a similar BCR, blocks with slab-type buildings tended to have a U that was higher by approximately 30%.

Key words： Chinese residential blocks; Morphological indices; Urban heat island; Outdoor thermal comfort; Microclimate simulation; ENVI-met