Examining the effect of neighbourhood geometry on ameliorating outdoor thermal comfort in hot and semi-arid climates

Rapid urbanization is placing increased stress on urban environments and reducing the usability of outdoor spaces, particularly in hot, semi-arid climates where pedestrians are exposed to significant heat stress. While outdoor thermal comfort (OTC) has been widely studied, limited research addresses residential neighbourhoods in such climatic conditions. This study investigates the spatial and temporal impact of urban geometry on OTC, focusing on variables such as Sky View Factor (SVF), aspect ratio (AR), street orientation, vegetation, and surface materials. Field measurements were conducted at 42 Locations across seven built-form typologies in Jaipur, India, during summer 9:00–21:00 h. The Physiologically Equivalent Temperature (PET) was computed using RayMan Pro software to assess thermal comfort at pedestrian level. Findings reveal that open low-rise areas with high SVF suffer from greater daytime heat stress due to limited shading, whereas compact low-rise configurations offered better thermal comfort. Optimal thermal performance was observed in areas with AR between 0.5 and 2.0. N–S oriented streets with high SVF exhibited poor comfort levels. Arcades and courtyards contributed to significant reductions in radiant temperatures up to 6.28 °C and 7.44 °C, respectively. Tree shading along E–W streets reduced Tmrt by 7.34 °C, and neighbourhoods with higher tree cover of 24 % demonstrated improved OTC. Unshaded asphalt surfaces recorded Tmrt values up to 11.15 °C higher than shaded counterparts. The study recommends integrating heat protection strategies, such as arcades and trees, along with heat mitigation elements like courtyards, as effective passive design interventions to enhance the thermal environment and improve outdoor comfort. • Compact low-rise built forms performed better thermally than open low-rise ones. •Areas with an aspect ratio between 0.5 and 2.0 showed better thermal performance. •SVF >0.5 and SVF <0.5 have different impacts during day and night. •Increasing AR is more effective for improving thermal comfort in N-S streets. •Arcades and trees can significantly lower SVF, without compromising AR.