UNSW working to mitigate heat vulnerability
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As millions have sweated through a heatwave that spread across mainland Australia earlier this week, concerns are being raised about the growing issue of urban overheating. Researchers from the University of New South Wales have created a national index to measure and then mitigate heat vulnerability in Australia’s towns and cities.
With 2023 being the hottest year recorded, the elderly, the young, and those with pre-existing health conditions are facing higher risks of heat exhaustion and heat stroke – which can lead to death.
The urban heat island effect
According to UNSW, extreme heat events claimed more Australian lives between 1900–2010 than the total number of deaths from all other natural hazards combined.
Some towns and cities are more vulnerable to the effects of heat due to the urban heat island (UHI) effect. Densely populated areas can experience increased ambient temperatures due to the buildings and carparks absorbing and reflecting heat.
Parts of Western Sydney experience dangerously high temperatures in summer due to the urban heat island effect, exacerbated by high-density developments, dark roofs and a lack of trees and green spaces. Photo courtesy of Nearmap, 2024.
UNSW researcher Associate Professor Lan Ding and her colleagues at the UNSW’s High Performance Architecture team are leading a project to provide a standardised approach to data collection and measurement of heat vulnerability, which includes the impact of the built environment.
Recording the adverse effects
The National Heat Vulnerability Observatory Index (NaVHO) will identify areas where populations are more vulnerable to the adverse effects of urban heat, and can inform of effective cooling interventions in the built environment. Heat vulnerability measurements quantify the effects of high temperatures on communities, including heat-related illness, energy consumption and outdoor thermal environments.
The data is then used to model the impact of different heat mitigation strategies and advise local authorities about which would be most effective in their locations.
A/Prof. Ding says addressing the impacts of urban heat vulnerability is critical for Australia to plan for resilient, sustainable communities to combat climate change.
“Concerningly, many of the places in Australia that are most vulnerable to extreme heat have been designed without enough of the features that mitigate heat, such as urban surface treatments, green spaces and trees with water irrigation, and water-cooling systems,” she says.
“This exacerbates the UHI effect and thereby intensifies the health, economic and environmental impacts of extreme heat for these populations.”
The NaHVO partnership
The NaHVO is a partnership between the NSW Department of Climate Change, Energy, the Environment and Water and UNSW’s High Performance Architecture team, and has an advisory committee with representatives from government, industry and academia.
It was set up in 2023 to develop national benchmark datasets and a consistent methodology to measure heat vulnerability in Australian towns and cities.
A/Prof. Ding says the ability to monitor heat vulnerability and identify cooling opportunities will enable those responsible for communities to see and measure the effects of urban overheating. It will also support urban planners, developers and architects to design smart, climate-resilient towns and cities.
Next steps
The team have just completed phase 1 of the project, where they built town-specific datasets for areas of Dubbo Region and Maitland City measuring heat vulnerability. They then modelled the potential effects of heat mitigation strategies and other planning decisions on those locations.
In both cities, the team was able to use the multi-disciplinary benchmark datasets to model how the use of cool materials (on roads, pavements and roofs) and increased urban greenery (through planting and irrigation) would reduce heat.
The project team also conducted “microscale” cooling potential analysis as part of the pilot.
Modelling showed that the use of cool roofs, cool pavement, greenery with water irrigation, water-misting and outdoor shading could reduce air temperature by 1.6°C in the areas studied in Maitland, and 2°C in the areas looked at in Dubbo – and lower the surface temperature by over 10°C in each location.
“We were able to compare the impact of scenarios, from altering subdivision lot sizes in a new development to changing the materials of roofing and hard surfaces, and provide data specific to those locations that showed how different decisions would affect temperatures and therefore everything from energy consumption to the health of the community,” says A/Prof. Ding.
“The more cities we collect benchmark data from, the more robust the NaHVO will be.”
After their success in Dubbo and Maitland, the researchers are now expanding the project to a further 21 cities in Australia.
Source: HVAC&R News
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