Building façade greening as a mitigation option for climate change in cities

Urban greening, through increased street level vegetation and urban parks, or vegetation affixed to buildings as green roofs and walls, is one technique to mitigate climatic impacts from both global climate change and urbanisation. Green walls and roofs have a dual benefit in that they can moderate atmospheric conditions both internal and external to the building.

This study quantifies the impacts of façade greening on a single prototypical building representative of an area undergoing urban renewal in an inner suburb of Sydney. The microclimate surrounding the building was simulated for a typical summer day using the three-dimensional prognostic micrometeorological model Envi-met. Simulations were undertaken for two vegetation species suitable for façade greening, one representing a native species ( Myoporum parvifolium a ground cover plant with a leaf area index of 1.5) and one representing an exotic species (Glycine max, a sub-shrub with a leaf area index of 4). The total amount of vegetation cover across the façade was also modified for different simulations. Whilst the impacts on surrounding microclimate were found to be small (< 0.3 °C) the green walls reduced outdoor surface temperature of the walls by up to 15 °C. Future work will evaluate the impact of this decrease in building wall temperature on building energy consumption.