QUANTIFYING THE IMPACT OF URBAN INFILL ON THE URBAN HEAT ISLAND EFFECT – A CASE STUDY FOR AN ALTERNATIVE MEDIUM DENSITY MODEL

Abstract. Urban Heat Islands (UHIs) impact the quality of life in many urban centres. Metropolitan areas of Australian cities and urbanised regional centres, in particular, show vulnerability towards UHIs due to challenging climatic conditions and the model of greater subdivision of established properties whereby backyards and mature trees are replaced with more residential dwellings and sealed areas. The measurements for the UHI mitigation, such as imposing reforestation, employing sustainable and medium density housing build form typology must be quantified. Simulation-based identification and mitigation of UHIs can be used for planning decisions. There are several advantages to use simulations. For instance, alternative subdivision design, building design and the placement of trees and other measures is only required in the digital twin. Experimenting with the digital twin saves resources and maximises the outcome by being able to quantify the heat reduction. The aim of this work is to quantify the impact of the current urban infill methods on UHI. We focus on an area that has gone through a process of re-subdivision that is bounded by roads within Perth, Western Australia. For the same area we propose an alternative design with an urban infill model based on a medium density housing guidelines with an improved green space allocation. While the current model shows significant effects of UHIs we could mitigate those effects in the alternative proposed model. In our simulation the hottest surfaces are roads with a temperature of approximately 45 °C at 2PM in the afternoon. In the current model close to 100% of the road surfaces reach this temperature. In contrast, in the alternative model only 45% of all road surfaces reach this temperature, significantly reducing the impact of UHI for pedestrian walking close by to those roads. At 2PM, the most frequent temperature of all surfaces for the current model is around 44 °C while the alternative’s model the most frequent temperature is approximately 28 °C – a difference of 16 °C.