Toward an oriented choice of building materials for improving the outdoor thermal comfort in hot dry climates

Abstract

This thesis addresses the challenges posed by rapid urbanization and climate change patterns, focusing on outdoor thermal comfort in hot dry environments. Investigating Biskra city, in Algeria, as a case study. It examines how external building materials, and street geometry affect pedestrian level thermal conditions. The research aims to provide evidence-based guidelines for sustainable urban planning in arid cities. By investigating the localized effects of building materials and street orientation, which have been largely underexplored in previous research, the study bridges critical knowledge gaps. A comprehensive literature review highlights the need for context-specific studies to better understand the interactions between urban geometry and building material properties in regions with extreme weather conditions. Field data collected in Biskra city, including air temperature and relative humidity, validated via ENVI-met simulations modeling with various street orientations (East-West and North-South), height-to-width ratios, and building materials parameterization (brick, concrete, adobe, and limestone). Therefore, deeper street canyons reduce surface temperatures but are less effective in mitigating thermal stress in East-West orientations, emphasizing the dominant role of street alignment. Complementing these findings, limestone as crucial material demonstrates optimal thermal performance, offering high cooling efficiency, particularly in North-South streets, through its reflective properties, which help retain less heat. However, building material choice has strong relationship to street orientation. Thermal comfort indices, such as Physiological Equivalent Temperature (PET), further validate these findings, with North-South streets achieving significantly lower PET index values. In conclusion, this thesis provides practical urban design guidelines, highlighting building materials selection and North-South street orientation as key components of a comprehensive strategy to enhance outdoor thermal comfort. The findings support sustainable urban planning by mitigating Urban Heat Island (UHI) effects, improving public health, and boosting urban resilience.