Experimental and simulation studies on the thermal behavior of vertical greenery system for temperature mitigation in urban spaces

Vertical greenery system (VGS) can provide a cooling effect on urban spaces. This paper conducted an experimental and simulation approach using the data logger and ENVI-met software during the summer and winter conditions in Tehran. The mean air temperature and relative humidity (RH) on those days were ~31.4 ºC with ~37.8% RH on the summer day and ~6.1 ºC with ~76% RH on the winter day, according to data retrieved from Tehran's Mehrabad Airport's synoptic station. The measurements were obtained on actual specification cases of VGS, and the temperature was recorded at certain points with definite distances from them. VGS were simulated in the ENVI-met on the same date. Hence, the purpose of this study is to evaluate of effect of thermal behavior on VGS in urban spaces in cold, semi-arid climate. The results showed that the temperature of VGS is cooler by 0.39-0.75 ºC in the summer and 0.39-1.26 ºC in winter. The effect of VGS was more remarkable at a distance of 0-0.5 m. Hence, building VGS creates and maintains an appropriate environment by reducing the temperature during the summer and increasing the temperature during the winter, creating a proper microclimate around itself. This is much more pronounced at a closer distance, but the effect fades away at a distance of 0.5 m.