Assessment of summer outdoor thermal comfort in an urban neighborhood with high-rise buildings

Abstract

The use of urban vegetation and ventilation corridors can be beneficial in terms of outdoor thermal comfort. High-rise buildings modify urban ventilation by redirecting incident wind flow, which can further complicate local thermal conditions. The present study investigates the interaction of building morphology and urban vegetation during heat wave conditions. A coupled multiscale approach is performed that allows for a detailed analysis of the local impact of vegetation and high-rise buildings in an urban neighborhood in Zurich, Switzerland. Existing configuration in the neighborhood with low-rise buildings of mostly uniform height is modified with high-rise buildings. Mesoscale meteorological simulations are employed to drive the flow in building-resolved computational fluid dynamics (CFD) simulations at microscale. The results show significantly lower air temperature around groups of trees and along main streets aligned with the predominant wind direction. However, there are also locations where air temperature increases due to the presence of trees, especially when there is limited exchange with the main ventilation corridor. Initial simulations with high-rise buildings show that they can have a large influence on air temperature in the immediate neighborhood.