On the energy impact of urban heat island in Sydney: Climate and energy potential of mitigation technologies

Abstract Urban Heat Island (UHI) is a phenomenon resulting in the increase of ambient temperature in dense areas of cities in comparison with rural areas. UHI has been demonstrated to be relevant in the Sydney metropolitan area, with a peak intensity of up to 6 °C. This has the consequence of increasing of up to three times the cooling demand of buildings. With the general aim of mitigating the effects of UHI in Sydney, several strategies, involving the use of outdoor surfaces with high Solar Reflectance and the use of greenery on outdoor surfaces at ground level and on roofs have been implemented and tested. Moreover, the benefits due to the adoption of mitigation technologies, in terms of reducing both UHI intensity and building cooling demand have been predicted. Results have shown that solutions involving the increase of the global albedo of the city demonstrate the highest benefits, achieving a reduction of peak ambient temperature of up to 3 °C and of peak cooling demand of residential buildings of up to 20%.