Stratified strategies for enhancing thermal comfort through multidimensional compactness optimization in urban built-up areas during heatwaves

Abstract

Thermal comfort (TC) in built-up areas with varying levels of compactness is unevenly affected during heatwaves (HW). However, identifying zones that should prioritize compactness optimization to effectively enhance TC is often overlooked. This study constructed a research framework for enhancing TC through stratified planning strategies by identifying key compactness-optimized areas and patterns during HW. Taking the built-up area of Shenyang, China, as an example, the compactness index containing spatial, functional and socio-economic dimensions and the TC index were first constructed based on multi-source data. Afterwards, different types of compactness-optimized areas, dominant compactness in different regions, and trade-off and synergy patterns among various dimensions of compactness were revealed using a geographically weighted regression model (GWRM) and local bivariate spatial autocorrelation analysis. The results show that compactness decreases from the center to the periphery of the built-up area, while TC follows the opposite trend. A total of 10 types of compactness-optimized areas are identified, including 8 key types covering 40.472 % of the built-up area. Based on the trade-offs and synergies between different compactness dimensions, 8 optimization patterns are revealed, with synergistic optimization across all three dimensions representing the largest share (71.256 %). Furthermore, 4 optimization categories with different priorities are identified, each exhibiting distinct spatial patterns and targeted optimization strategies. These findings support hierarchical resource allocation and strategic intervention to enhance thermal comfort and promote climate-resilient cities.