Air pollution in urban street canyons presents a serious health risk, especially in densely populated areas. While previous research has explored airflow characteristics in these canyons, it often lacks detailed data on pollutant dispersion and the effects of wind speed on airflow patterns and vortex formation. This study uses Computational Fluid Dynamics (CFD) to deliver quantitative measurements of pollutant dispersion rates and qualitative insights into airflow patterns across various street canyon morphologies. The analysis examines a range of aspect ratios (ARs), from wide (AR = 0.75) to narrow (AR = 4.5), and different wind speeds to evaluate their effects on pollutant dispersion. Findings indicate that purging flow rates decline as the AR increases, with a more pronounced decrease at lower AR values. In narrower streets, airflow patterns are particularly sensitive to wind velocity, leading to unexpected vortices that hinder effective pollutant dispersion. By incorporating these insights into urban design strategies, cities can enhance street ventilation, thereby reducing pollutant concentrations and improving public health. This study also tests a specific street layout in Seville to predict pollutant accumulation under various conditions, assessing health risks based on World Health Organization guidelines. Ultimately, this research aids in developing healthier, more sustainable urban environments.

Natural ventilation in hot climates represents a key strategy to reduce the dependence on mechanical cooling systems, especially in historic buildings, where it is essential to balance thermal comfort and heritage conservation. This study analyses the effectiveness of various natural ventilation strategies in a historic building located in Écija, Seville, which is characterised by a warm climate with nocturnal thermal dips. Experimental data obtained during a summer monitoring campaign were used to validate computational fluid dynamics (CFD) models and thermal simulations. In addition, an efficiency index was defined to quantify the indoor temperature reduction. The results show a cooling efficiency close to 40%, achieving an average reduction of 3 °C in the indoor temperature during the summer. Simulations of different modes of operation of natural ventilation show a 30% improvement in comfort hours according to Spanish regulations and a 50% reduction in the thermal difference during non-comfort hours. This work demonstrates that natural ventilation can significantly improve indoor conditions, offering a sustainable and replicable approach for historic buildings in hot climates.

Urban heat islands are an environmental hazard which degrade people’s lives worldwide, reducing social life and increasing health problems, forcing scientists to design innovative acclimatization methods in public places, such as sheltering. This paper focuses on providing quantitative indicators about airflow rates and qualitative information about airflow patterns in street canyons for typical street canyon morphologies, which is essential when designing outdoor acclimatization strategies to mitigate urban overheating. This is based on CFD simulations using an enhanced numerical domain model, which can reduce computational cost and simulation time. The study is performed for different ARs, from wide (AR = 0.75) to narrow (AR = 4), and wind speed to characterize their effect on street ventilation The results show that air renewal decreases while the AR increases. The reduction is faster for a low AR and then comes to a standstill for a high AR. In addition, the study shows that inside narrow streets, the pattern of airflow is affected by the wind velocity magnitude. These findings provide numerical values of air ventilation for a wide range of typical street canyon configurations, which represent essential data for designing effective climate control strategies, mitigating urban heat islands and conducting outdoor thermal comfort studies. This work contributes valuable knowledge to the multidisciplinary efforts aimed at enhancing urban living environments.