Exploration of Urban Shade Accessibility and Improvement Paths for Outdoor Thermal Comfort from the Perspective of Blue-Green Infrastructure

Abstract

How to Increase Shade Availability and Improve the Outdoor Thermal Environment of Cities with Blue-Green Infrastructure. Rather than providing new empirical data, it collects existing research on green and blue infrastructure, urban microclimates and thermal comfort indices to propose a path for integrating vegetation and water in heat-resilient public spaces. First, in this discussion, the concept of urban resilience and heat reduction provided by blue-green infrastructure through shading, evapotranspiration and modification of surface energy balance will be introduced; then, it will be explored how trees, ground cover and water bodies specifically alter radiant and air temperatures in streets, parks and waterfronts. According to biometeorological studies using indices such as physiological equivalent temperature (PET) and the Universal Thermal Climate Index (UTCI), this paper introduces design variables that affect the perception of thermal comfort, including sky view factor, canopy cover, configuration and accessibility. Shade accessibility should be considered a problem of spatial inequality in the planning of blue-green infrastructure, and all people need to be able to reach a cool microclimate during a heatwave. Finally, the paper proposes some practical rules for combining shade, ventilation and moisture in urban design, and does not make excessive claims about cooling performance beyond what has been reported in the cited literature.