Numerical simulation of layout and landscape elements on the thermal environment of urban squares

Extreme urban heat poses significant challenges to the resilience and livability of cities. Urban squares are important open public spaces in cities, serving as main locations for residents' leisure and recreational activities and reflect the identity and cultural background of the cities. Improvement in thermal comfort in urban squares can improve the quality of the urban environment and help mitigate the urban heat island effect. This study developed 18 layout and landscape combination scenarios based on statistical analysis of data from 100 urban squares in regions with hot summers and cold winters. Further, the effectiveness of the proposed design solutions in improving the thermal environment was comprehensively analyzed. The results show that: 1) The block array layout with vegetation, water bodies, and permeable tiles is the most effective scenario, with a PET of 31.84 degrees C, approaching a comfortable level of heat stress; 2) Among the three layouts, the block array layout optimizes thermal comfort better than the main view entrance layout and main view center layout, and reduces physiological equivalent temperature by 10.51-10.77 degrees C compared with that of the other two layouts; 3) Scenarios incorporating water bodies provide better optimization effects than those with only trees, even when the total area covered by greenery remains unchanged; and 4) Permeable paving materials with high albedo more effectively improve the thermal comfort. Our results highlight a great potential of comprehensively using multiple landscape strategies to improve outdoor thermal comfort, and provides design basis for enhancing thermal comfort in similar sized urban squares in hot summer and cold winter areas.