4 July 2013 — With Australian cities getting hotter, and heat waves becoming more frequent, finding ways for cities to adapt and build resilience is imperative.
A project led by the University of South Australia is doing just this, having been granted $1.2 million, including from the CRC for Low Carbon Living, to tackle heat stress in Australian cities. And our buildings are a key target.
“Cities are getting hotter and it’s a serious issue,” said project leader professor Steffen Lehmann. “Heatwaves can and do kill, and as the planet warms we are going to experience more of the same.
“We need to ask what happens in public spaces when older people and young children are not able to go out because of the heat. How do we build cities that mitigate heat stress and the storage of heat?”
The UniSA project will examine urban microclimates in Sydney, Melbourne and Adelaide in a project spanning three years and bringing together three universities and eight industry and government partners, including SA Urban Renewal Authority, BlueScope Steel, Hassell Architects, the City of Sydney and CSIRO.
The project will focus on the urban heat island effect, and research “the interplay between urban form, density, materials, surfaces and ambient temperature”, said Professor Lehmann.
The urban heat island effect is found in metropolitan areas where a microclimate is created due to human activity. Urban development is a big culprit as original land surfaces are diminished and replaced with dark energy-absorbing roads and buildings. It is also caused by waste heat from airconditioning units, which often need to be used more to combat the effects of heat increases, further exacerbating the problem.
“The heat stress that people experience in cities can be considerable, often much more intense than in less built up areas,” said Professor Lehmann.
He told The Fifth Estate that in the past cities used to cool down overnight – when you came into the CBD of a morning the heat from the previous day had dissipated. Now, due to an excess of anthropogenic heat, it’s just not happening anymore.
Professor Lehmann said that the project is the first of its kind, and will provide important information for architectural, precinct and city development.
“It’s never been done to this extent,” he said.
However, he said we needed to look far beyond green roofs to solve the problem.
“They’re fantastic and we love them, but what do we do in the suburbs where we can’t put green roofs in?” he said.
Cool roofs and cool buildings were other areas the project would delve into.
“Building materials, surface colours and pavement all have a significant effect,” he said.
Black tiles on roofs were currently an “unfortunate fashion” with developers that needed to stop, Professor Lehmann said, saying they were one of the worst thing you could do to a building.
He said that the effect of black roofs was to absorb more heat energy, leading to greater cooling loads needed. This equates to more greenhouse gas emissions and increased energy costs.
“Black tiles are to be avoided,” he said. “We suggest to Sydney, Melbourne and Adelaide to legislate and change the building code against the use of black coloured or heat trapping tiles.”
City of Adelaide Lord Mayor Stephen Yarwood said the research project would have tangible benefits for Australian cities.
“While there is a considerable body of international UHI research, this project will apply that knowledge to Australian cities and their particular issues, comparing the built environment in Sydney, Melbourne and Adelaide,” he said.
After this project, Professor Lehmann said the next target was three large Chinese cities, with populations of greater than 10 million people. He said that due to their climates, the urban heat island effect there was having particularly serious consequences.