Integrating Thermal Comfort Considerations into Urban Street Design Guidelines in a hot and humid climate

Urban street canyons significantly influence the microclimate within an urban area, impacting factors such as solar radiation, wind flow, and air temperature. Vijayawada, ranked as the second most heat stressed city in India, where microclimates in street canyons can increase the urban heat island effect due to reduced ventilation, heat accumulation, and discomfort in outdoor spaces, especially in densely built areas. The present street design guidelines in India primarily focus on mobility, safety, and accessibility while overlooking the role of thermal comfort of pedestrians. Therefore, the study aims to bridge this gap by evaluating the impact of urban design parameters on outdoor thermal comfort within an urban street canyon in Vijayawada and examining how factors like street geometry, aspect ratio (height-to-width ratio), orientation, materials and vegetation interact with the local microclimate. Street canyons in LCZ 3, LCZ 5 and LCZ 6, in N-S orientation were selected to capture varying urban morphologies and microclimatic conditions. Air temperature, relative humidity, wind speed and solar radiation were measured using mobile weather station. A questionnaire survey was conducted among 198 respondents to record their thermal perception. The subjective perceptions were analyzed against the on-site measurements to identify the adaptive comfort range. Further, the urban design parameters and their impact on thermal comfort were analyzed using EnviMET simulations.The findings indicate that urban morphology, material choices, and the presence of greenery significantly affect pedestrian comfort levels, with vegetation and shading emerging as critical mitigation strategies against heat stress. Pedestrians found LCZ 6 (open low rise) to be the most comfortable since it provides for better air flow and ventilation, featured more vegetation and pervious land cover, and reduced heat accumulation due to less paved area and low building density. The comfort range found was 23 °C – 32 °C for the pedestrians.