Impact assessment of green infrastructure on surrounding microclimate (case study: Tehran's Nature Bridge)

摘要

In recent decades, establishing green roofs has been used as a method to mitigate urban heat islands and air and sound pollution in most modern cities. This study was carried out on a hot summer day in July 2015, in the city of Tehran, Iran. In the study, the ENVI-met model was applied to simulate the impact of Tehran's Nature Bridge green roof as a green infrastructure on its surrounding microclimate. Accordingly, two simulation scenarios were generated to assess the impact of extensive and intensive green roofs on relative humidity, air temperature and wind speed. In the first scenario (control), the green roof was excluded from the study area map (i.e., The Nature Bridge) and in the second one, both intensive and extensive green roofs existing onthe Nature Bridge were included. The comparison between the scenarios was made at two different heights, 1.5 m to assess the effects of green roof on ground level, and 40.5 m to assess the effect of green roof on the bridge level. Maps showing the simulated situation of two times, 10 am and 4 pm, are presented in results of this study. Results of the second scenario showed 10.47% increase in relative humidity (RH) in comparison to first scenario on bridge level at 10 am. In the second scenario, air temperature dropped by 0.8°C at 10 am compared with the first scenario that is equivalent to 2.87%. Presence of intensive green roof caused a decrease in wind speed on bridge level by 1.75 m s1 and changed its direction. Green roof also influenced speed and direction of wind, RH and air temperature in different ways at ground level. Overall, the green roof altered climatic parameters such as air temperature, RH, and wind speed and direction at both bridge and ground level.