Impact of wind on pedestrian comfort in the urban environment: wind discomfort, heat stress and rain exposure

Source abstract

ABSTRACT This study addresses the interaction between pedestrian wind, thermal, and rain exposure comfort in a high-rise urban environment, using Geneva, Switzerland, as a case study. Multiscale simulations with urbanMicroclimateFoam and w indDrivenRainFoam are used to quantify wind comfort, heat stress during heatwaves, and annual rain exposure. The results show that high-rise induced downflow, corner streams and channeling flows generate localized wind acceleration, increasing wind discomfort and rain exposure in exposed street corridors while simultaneously improving thermal conditions during heatwaves through enhanced ventilation. In contrast, thermal discomfort concentrates in sun-exposed courtyards and near south-facing façades with limited shading, whereas sheltered zones such as building wakes reduce wind and rain exposure. For this specific case study, wind discomfort affects 39% of the pedestrian area, strong and very strong heat stress together cover 91.5%, and 97% of the domain exhibits rain exposure values above 0.9, indicating generally high exposure conditions across most pedestrian spaces. Wind and thermal discomfort overlap in only 8% of the study area, indicating that wind-exposed discomfort zones are generally associated with comparatively more favorable thermal conditions. The overlap regions of wind discomfort, excessive heat stress, and high rain exposure are limited but spatially concentrated in key pedestrian areas, where multiple stressors coincide. These findings highlight the multidimensional and sometimes conflicting nature of pedestrian comfort, where mitigation of one stressor may exacerbate another. Although case-specific, they indicate that priority should be given to these overlapping high-stress zones, particularly in areas of intense pedestrian activity such as waiting areas, and resting spaces.