Effects of vertical greening on the thermal environment and energy consumption in different street canyons

Vertical greening is vital for energy conservation and urban sustainability. However, previous studies have seldom considered the energy-saving effects of vertical greening within street canyons-an important representative urban model. This study employs ENVI-met and EnergyPlus to evaluate the energy savings of vertical greening in twelve typical street canyon scenarios with varying aspect ratios (H/W = 1, 2, 4) and orientations (North-South, East-West, Northeast-Southwest, Northwest-Southeast). We quantified the relative contributions of building surface temperature reduction (Delta Tse) and air temperature reduction (Delta Ta) to overall energy efficiency. Remarkably, our findings reveal that Delta Tse accounts for over 97 % of the total energy-saving contribution-a novel insight contrasting with previous studies that emphasized combined impacts. Additionally, the results indicate that stronger solar radiation in street canyons leads to greater reductions in building surface temperatures. To achieve maximum daily energy savings, the optimal combinations of street orientation and aspect ratio are: North-South orientation when H/W = 1, Southwest-Northeast when H/W = 2, and Northwest-Southeast when H/W = 4. This study is among the first to quantify the combined effects of different street canyon configurations and vertical greening on urban energy savings, providing effective methodologies and new insights for implementing sustainable urban vertical greening.