Impact of street interface permeability on ventilation and pollutants dispersion in urban street spaces
Wen Liu, Zhengdong Huang, Dongjin Cui, Ding Ma, Shuo-Jun Mei, Renzhong Guo
Abstract
• Street interface permeability affects ventilation and pollutant dispersion. • Upstream interface permeability effectively enhances pollutant dispersion in streets. • Staggered layout with SIP up > SIP down generally provides a better air environment. • A 20% street interface permeability configuration is recommended. • Urban design guidelines should incorporate street-scale permeability. The concept of permeability has been widely utilized in urban planning to improve ventilation for alleviating hazardous air pollution. However, the influences of street-scale permeability on the wind environment and air quality in urban streets have not yet been fully explored. This study employed three-dimensional numerical simulations validated by the wind tunnel experiment to investigate the impact of street interface permeability (SIP) on natural ventilation and pollutant dispersion in urban street spaces. Two building layouts formed by non-uniform street interface permeability configurations – that is, aligned and staggered arrangements – were discussed simultaneously. The results show that the airflow regimes and pollutant dispersion processes inside urban streets are mainly determined by the upstream interface permeability configuration. Urban streets with higher interface permeability generally exhibit lower air pollution levels. Specifically, increasing the permeability of the upstream street interface can more efficiently enhance air movement and pollutant removal in the urban street space than that of the downstream. The staggered layout with greater upstream street interface permeability than downstream has overall better ventilation conditions and air quality than other layouts. A street interface configuration with SIP = 20% is recommended as a best-of-both-worlds solution to strike a balance between improving the air environment and creating a pleasantly scaled street space. The findings could provide valuable insights for urban planners in terms of improving the street air quality and refining the human scale-led urban design guidelines to promote the environmental quality of public spaces.