Density Planning Shift Fuels Urban Heat Island Fears

Australia has warmed by about 1.51°C since national record-keeping began in 1910. Globally we’re on track for 3.6°C of warming by the end of the century. At this rate, according to climate scientist Joëlle Gergis, the catastrophic bushfire season of 2019-20 will look like an average summer within the next 15 years. “If you think of 2°C of global warming, what that starts to mean in a country like Australia is 50°C summer temperatures,” Gergis told an Investor Group on Climate Change conference last month. “By 3°C that becomes an average summer in parts of southern Australia.” Under those conditions, our buildings, cities, and lifestyles will change in ways almost unimaginable. Urban heat island effects compound the impact of global warming, with western Sydney a notable example. During heatwaves, the western suburbs can be up to 10°C hotter than the east. Penrith recorded a high of 48.9°C on January 4, 2020, making it the hottest place on Earth at the time. It was not the first time that was the case. Adaptation to those levels of heat and mitigating the factors that cause and compound global and urban warming need to be designed into our built structures and their layout, experts say. Urban cooling must be planned for at citywide, precinct and microclimate levels—and urgently. ▲ Paris is taking massive, urgent steps towards mitigating urban heat. Professor of Urban Management and Planning at Western Sydney University Sebastian Pfautsch says that permeable pavements, reflective roofs and urban greening are among initiatives that need to be deployed immediately. “These are the things that we want to see at scale, not a pilot here or there. We’re past that,” Pfautsch told The Urban Developer . “We know how these things work, there’s lots of science out there, so it’s not necessary to have another feel-good project for someone that gives you a green roof, and then they can have a five-star or six-star Green Star building.” Other cities are already implementing massive cooling projects. Singapore, a notably hot, humid and monsoon-prone jurisdiction, recently unveiled a roadmap to cool the entire island of Sentosa using a combination of technology, design, greening and materials science. The most successful elements will be rolled out across the entire country in coming decades. Pfautsch says that there are cities in Europe preparing for future temperatures that Australian cities are already experiencing. “Paris has set a target of being 50 per cent porous by 2030 and it looks like they will achieve that. They’re looking at ripping up streets. They’re looking at getting rid of parking for cars inside the city, they’re looking at installing rooftop gardens wherever they can,” Pfautsch said. “They literally closed city highways and gave them back to the people, where they now have a gravel pathway on the sand. [There are] movies that have car chases on these roads and they are now parks.” In Western Sydney, meanwhile, suburbs are already experiencing heat effects that will have generational impacts. Overheating to the point where it becomes unviable to have a social life outdoors is affecting children’s activity levels and development, according to Pfautsch, and will have health and lifestyle implications in future decades . Homes for hundreds of thousands of residents are going up in Western Sydney, Pfautsch says, “without really knowing how we’re doing this, so that they are safe and they can have a dignified life, without paying thousands of dollars for cooling energy requirements”. Developers must get behind urban cooling push Ark Resources managing director Jan Talacko says that, at the moment, mismatches between intentions, systems and incentives are not leading to optimal urban cooling outcomes at a project level. “We’re rapidly watering down planning controls so that there’s more activity and more residential projects approved. As that happens, the fear is that density means less greenery, exacerbating the climatic effects locally and regionally and globally,” Talacko says. ▲ Greenery can be used for urban cooling at building, a suburb or city level. Research by Pfautsch also supports that idea, showing that Marsden Park in Sydney’s west has just 1 per cent tree canopy cover, compared to the NSW target of 40 per cent, and that maximising available planting locations leftover from development would only yield 17 to 22 per cent coverage. While strategies and targets exist at all levels of the property development process, Talacko says that “the real problem is that there’s no clear set of rules or requirements that requires developers to do what we would consider to be a great job”. Talacko sits on the advisory board for Nature Based Cities, whose report in conjunction with Urbis found residential projects that integrated greenery had significant commercial uplift. “I don’t think that’s any surprise to most people … everyone’s aware that there’s a benefit,” Talacko said. Nature Based Cities has been working on providing tools so that developers can integrate greenery into projects in a way that demonstrates to the market, and to planners, the commercial, cooling and other benefits. “We’re trying to avoid more regulation or more green tape, so our focus is on encouraging and rewarding the developments that take this approach,” Talacko said. “It’s aligned with what we need to do in our cities to cope with the climate as it changes, inevitably, even if we manage to keep it to 2°C.” Developers need help to cool microclimates Talacko says that the microclimatic effects of greenery are tangible and obvious. “At a localised level, if there’s extensive planting compared to a large area of concrete or bitumen…we all know that if you go and sit in a park on a hot day, you get much more comfort. So the microclimate which is created by planting will mitigate the effects of heat.” ▲ Cooling effects are tangible, but more localised heat measurement data are also necessary. Pfautsch, too, is working on project-level tools such as the Cool Suburbs application, which he suggests would be appropriate for integration into the Green Star system. That tool “can cope with any type of development, at any stage of the development. So at masterplanning, before the DA, during the DA … from a single home to a whole suburb”. Pfautsch says that councils can support developers and residents by building local heat measurement networks to understand microclimatic effects. While the Bureau of Meteorology has just 22 stations across Sydney, Pfautsch has measured differences of more than 15°C across only a few kilometres— from the Botanic Gardens, to St Peters in Sydney’s inner west. “If you do this in Penrith, or if you do this across Blacktown, you will find the same kind of thing. Blacktown is the largest LGA ... in Greater Sydney, has the highest population density and has zero meteorology weather stations,” Pfautsch says. With the right network of smart sensors, localised misting of green belts can take place a few days before an impending heat wave, for example, turning greenery into air conditioning systems. However, don’t expect to bolt on technology and think it will save a project or a city post-facto. Designing for a warming climate and integrating heat consciousness into the planning process are the foundation of liveable urban environments. “I always think, from experience, you can only be as smart as you build capacity in your organisation to be smart,” Pfautsch said. “Smart [technology] is great, but you need smart people and resourcing to really make that work.”

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ExclusivePatrick LauFri 31 Oct 25

Density Planning Shift Fuels Urban Heat Island Fears

Get the full story.

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