Interdependent Influence of Walkway Width, Vegetation Type, and Sky View Factor on Human Thermal Comfort in Park Walkways

Understanding how to select the most thermally comfortable walkways in urban parks—based on weather conditions and spatial characteristics—can greatly benefit urban outdoor exercisers under the growing intensity of urban heat islands and the increasing frequency of heatwaves in cities. To reveal the correlation between spatial characteristics and human thermal comfort of walkways in urban parks, this study focuses on the Tiergarten, a central historical park in Berlin, Germany, which offers diverse walkways and green spaces for outdoor activities. We conducted a 24-hours field measurement in nine different types of walkways in Tiergarten, combining three walkway widths (3m, 5m, 7m) and three vegetation types (Grass, Tree & Grass, Tree & Shrubs). Besides, we conducted microclimate simulation involves 15 idealized scenarios with different  Sky View Factor (SVF), vegetation types, and walkway widths, modelled using ENVI-met® Science V4.3.2. Human thermal comfort was assessed using Physiological Equivalent Temperature (PET), calculated with RayMan Pro Version 2.3 Beta. Key findings include: (1) human thermal comfort on walkways is jointly influenced by SVF, vegetation type, and walkway width. SVF emerges as the dominant factor, followed by vegetation density and walkway width; (2) The interdependent influence of these factors varies between day and night; (3) at nighttime, walkways with high SVF, sparse vegetation type, and greater width show lower PET values; (4) at daytime of a sunny summer day, narrower walkways with low SVF and dense vegetation type provide better thermal comfort. However, when there is a breeze, wider walkways with sparse vegetation and low SVF offer lower PET values. A thermal comfort map for Tiergarten was developed based on these findings, which can guide pedestrians in selecting the most comfortable pathways during heatwaves. The results also provide valuable insights for the design of climate-adaptive park walkways in urban areas.