Influence of Environmental Factors on Pedestrian Summer Vitality in Urban Pedestrian Streets in Cold Regions Guided by Thermal Comfort: A Case Study of Sanlitun—Beijing, China

In the context of increasingly extreme high temperatures during the summer in cold regions, the spatial vitality of urban blocks is significantly affected. In order to enhance the summer vitality of sustainable urban neighborhoods, this study explores the mechanisms of street elements and vitality under the guidance of thermal comfort. Taking an urban pedestrian street in Sanlitun, Beijing, during a summer day as the research subject, this study systematically analyzed the impact of environmental factors such as street orientation, aspect ratio, three-dimensional greenery of trees, and tree spacing on the thermal comfort of street space. By quantitatively analyzing the relationship between thermal comfort and pedestrian vitality in different street spaces, this study reveals the mechanisms by which environmental factors enhance the summer usability and spatial vitality of pedestrian streets. The research results indicate that street vitality shows a gradually increasing trend throughout the day, particularly between 12:00 and 16:00, when thermal comfort significantly affects people’s vitality. Furthermore, univariate analysis reveals that the street aspect ratio is the primary factor influencing the spatial vitality of the southern section of the Sanlitun Taikoo Li pedestrian street, with a characteristic average of 8.28 over a week. Finally, the results of the multi-factor analysis show that, when enhancing street vitality, priority should be given to the interactions between street aspect ratio, tree greenery, temperature, and physiological equivalent temperature, where the correlation coefficient between street aspect ratio and vitality is 0.70, and that between temperature and physiological equivalent temperature is 0.63, both showing positive correlations. Research shows that, in street planning, a reasonable building aspect ratio (1:2 to 1:4) and scientific green design are key. By carefully controlling the planting density and greenery configuration of trees, optimal street space effects can be achieved. This study proposes sustainable urban design strategies by optimizing street space design and improving environmental thermal comfort, aiming to enhance the summer vitality of urban blocks in cold regions and advocate for a sustainable development model that combines ecological and social benefits.