A study of the impacts sky view factor on urban environments and pedestrians' comforts

Urban environmental quality (EnQ) encompassing thermal comfort and air quality is a critical determinant of urban livability. Global warming and urban heat island have sharpened their negative effects. The sky view factor (SVF), a key metric of urban geometry, is known to influence EnQ, but its integrated and context-dependent effects across different urban settings remain inadequately quantified. This study presents a comprehensive field measurement investigation in Chengdu, China, a humid subtropical megacity, employing a comparative approach with synchronized microclimate monitoring and extensive questionnaire surveys (N = 1692) across contrasting street and park settings. findings in this study reveal a fundamental context-dependency in both environmental mechanisms and human perception. Pedestrians exhibited high thermal sensitivity, with neutral physiologically equivalent temperatures (PET) of 24.2 °C in streets and a significantly lower 19.2 °C in parks. In contrast, sensitivity to air pollution was weaker, with a discomfort threshold for PM2.5 identified at 46 µg/m³. Crucially, the dominant factors shaping environmental quality diverged between settings: in streets, thermal comforts were primarily governed by surface albedo, whereas in parks, it was predominantly controlled by SVF. A striking paradox was observed for air quality; contrary to conventional understanding, multivariate analysis controlling for traffic variables showed that higher SVF was associated with increased PM2.5 concentrations in street canyons, yet it facilitated pollutant dispersion and improved air quality in the park. These findings underscore the complex and often countervailing interplay between urban form and environmental performance. The study provides a robust, evidence-based foundation for moving beyond one-size-fits-all solutions, advocating for context-sensitive urban design strategies that are precisely calibrated to the distinct environmental logic of streets and green spaces to enhance pedestrian comfort and public health.