The cooling effect of vertical greening systems using solar radiation measurement

Vertical greening systems (VGS) can effectively mitigate the urban heat island effect in urban canyons with dense high-rise buildings. This study evaluates the cooling effect of VGS on solar radiation and atmospheric temperature. A thermodynamic analysis was utilized to assess the impact of VGS on outdoor thermal comfort. CNR4 equipment collected data on long-wave and short-wave radiation from Fatsia japonica plants. These data formed the basis for simulation analyses with the Envi-met model, which showed that VGS exhibit significant diurnal surface temperature variations in the urban environment during the summer months. Areas with VGS had higher temperatures than those of high albedo walls (HAW) from 2:00 to 4:00 and recorded lower temperatures than those of HAW between 13:00 and 15:00. VGS absorb short-wave and long-wave radiation better than HAW. The average short-wave radiation of VGS is 43.91 W/h², compared to 31.50 W/h² for HAW, while the average long-wave radiation of VGS is 2.82 W/h², compared to -1.53 W/h² for HAW. Envi-met simulations indicate that the surface temperature of the VGS decreases after 15:00, to about 0.1°C cooler than HAW. The data from July 15 indicate that VGS significantly outperformed HAW in terms of cooling the maximum temperature at 13:00 and stabilizing the minimum temperature at 3:00. Furthermore, the extent of the cooling effect of the VGS was approximately 1.5 meters. This demonstrates that VGS, as an eco-friendly solution, can improve the urban thermal environment, increase the urban greening rate, and promote ecologically balanced development.