The influence of greenery on reduction of air temperature and air pollution in an urban canyon; A case study

Abstract

Abstract Outdoor ambient air temperature and air quality are considered as a main health concern whereas 66% of the world's population live in cities by 2050. The current study aims to evaluate the effect of different types and location of greeneries as well as building heights and wind orientation in urban canyon .The research applied the numerical simulation to model a street canyon with different scenarios. The study, focusing on PM10, PM2.5 and NOx concentrations in hot-arid district. The results showed that stepped buildings with green walls has the highest temperature of 18.02° C, and two rows of deciduous trees has the lowest temperature of 17.56° C as the best and worst scenarios simultaneously. Comparison of scenarios (with and without trees) indicated that the efficiency of trees and vegetation on the moderation of thermal comfort. Scenarios 1, 2, 7 and 8 which are without trees, have a high degree of temperature. However, scenario 5, with two rows of deciduous trees, has the lowest temperature and the highest pollution. Moreover, a significant correlation between wind flow and reduction of air temperature and pollutant have been observed. This study presents the novel design pattern of ventilation for air pollutant removal, moreover develops a scenario with maximum coverage of streets and walls with suitable plants, Using the right planting technique, choosing the right plants and trees for urban streets, building walls, and installing green roofs, these findings might aid urban designers and architects in creating more sustainable cites.