Abstract
As the frequency and intensity of heatwaves are growing in Australia, strategies to combat heat are becoming more vital. Cities are exposed to urban heat islands (UHIs) due to excess urbanisation. In this study, a definition of urban heatwave (UHW) is conceptualised to investigate the combined impacts of heatwaves and UHIs. To quantify the negative impacts of UHW, indicators—such as excess morbidity, electricity and water consumption—are considered. The intensity of UHWs is calculated using the unit of excess heat factor (EHF), developed by the Australian Bureau of Meteorology. EHF enables the comparability of UHWs in different geographical locations. Using the indicators and the intensity of UHWs, a calculation method to quantify heatwave resilience at a precincts scale is proposed. The study summarises the assumed influential factors of precinct heatwave resilience based on the existing literature and propose a “cool retrofitting toolkit” (CRT). CRT creates the framework to assess the adaptation to and mitigation of UHWs available to retrofit existing precincts, and to evaluate potential retrofitting strategies in terms of energy and carbon efficiency, financial affordability and perceived acceptability by population. This study illuminates the importance of climate, function, built environment and population characteristics-conscious retrofitting.
Highlights
The “Fifth Assessment Report” of the Intergovernmental Panel on Climate Change noted the continuous increase of global mean surface temperatures since the late 19th century [1]
The urban heat island (UHI) is one of the adverse impacts caused by urbanisation and is defined in the discernible temperature difference between urban and rural areas [5]
The ultimate goal of this paper is to summarise the principles of an evaluation tool for potential retrofitting techniques against heatwaves at precinct scale, considering cost—and energy efficiency and the location—and precinct-specific characteristics
Summary
The “Fifth Assessment Report” of the Intergovernmental Panel on Climate Change noted the continuous increase of global mean surface temperatures since the late 19th century [1]. The risk of climatic extremes is growing as a consequence of increased greenhouse gas emissions caused by human activities [2]. These emissions will potentially raise the overall temperature in Australian cities by up to 1.2 °C by 2030, up to 2.2 °C by 2050 and up to 3.4 °C or more by 2070 [3]. Urbanisation has negative impacts that reduce significantly both the efficiency and liveability of cities. The urban heat island (UHI) is one of the adverse impacts caused by urbanisation and is defined in the discernible temperature difference between urban and rural areas [5]. The phenomenon is ascribed to the combination of inappropriate use of building and urban materials, urban morphology, the lack of urban vegetation, the extensive coverage of the stormwater sewage network, anthropogenic heat generation, altered wind patterns and increased air pollution in cities [5,6]
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