Quantifying impacts of the City of Sydney's urban forest strategy on residential microclimate

As a strategy to mitigate impacts of the urban heat island the City of Sydney has implemented an urban forest strategy aimed at increasing canopy cover across the city from the current level of 15.5% to 23.25% by 2030. This study quantifies the impacts of these proposed increases in urban greening on a site undergoing urban renewal in an inner suburb of Sydney that is actively including substantial urban greening. The site is currently being transformed from large, inner-city industrial to medium to high density mixed-use residential and commercial. It is located at the boundary between the central business district and mid to low-rise residential areas and provides the opportunity to investigate a real-world example of urban renewal in Sydney, future developments may be of similar scale. The area also has two urban meteorological stations providing important data for model validation.

The site's microclimate is simulated for a typical summer day using the three-dimensional prognostic micrometeorological model Envi-met. Simulations are undertaken for a variety of vegetation coverage scenarios, including: no vegetation, current canopy with impervious surface cover; current canopy with ground level vegetation; future canopy with impervious surface; and future canopy with ground level vegetation. Effects on temperature, atmospheric moisture, wind speed and human thermal comfort are compared spatially and over the diurnal cycle to determine impacts of both canopy and surface vegetation on the microclimate, and to determine optimum configuration and type of vegetation cover to best mitigate the urban heat island.