Impact of block morphology on urban thermal environment with the consideration of spatial heterogeneity

•A new classification system for block morphology is proposed.•The GWR model confirms the existence of spatial heterogeneity in the LST.•LST is positively correlated with the intensity of block development.•BD is the most critical indicator affecting the LST.•Based on spatial heterogeneity, different urban planning schemes are proposed. Block thermal environments affect public health and the sustainable development of cities. However, the study of spatial heterogeneity of block morphology in thermal environments needs further research, and exploring a new classification system of block morphology will also be beneficial to urban management. Taking 1426 blocks of Dalian city as an example, this paper proposed a new classification system of block morphology (HDR system) by a two-step cluster. Pearson coefficient, ordinary least squares (OLS) model, and geographically weighted regression (GWR) model were applied to explore the mechanisms of building height (BH), building density (BD), and plot ratio (PR) on land surface temperature (LST) globally (non-classification) and locally (classification system HDR1–5) respectively. The results are as follows: 1) Low-floor buildings dominate Dalian's blocks. 2) Greater intensity of block development is associated with greater LST. 3) BH, BD, and PR show significant spatial heterogeneity on LST. 4) LST is most notably affected by BD. 5) HDR5 is recommended as the preferred block plan to face the worsening of the thermal environment. The results of this study provide direct references and implications for city managers and designers who want to develop practical and sustainable policies and norms for urban renewal and new blocks.