A four-dimensional model of Braddon which shows the history and composition of the suburb's buildings and land use over time could be used as part of a system to assess the environmental impact of new development across Canberra, new research suggests.
Researchers at the CSIRO developed the model of Braddon's "urban metabolism", showing how the suburb has changed over time and what the environmental impact has been, and say the model could be expanded to cover the whole of Canberra to inform sustainable development practices.
Dr Heinz Schandl said as cities become more efficient with their energy use, the environmental impact of physical buildings would need to be carefully considered for cities to become truly carbon neutral.
Three quarters of the available global carbon budget to keep the planet within 1.5 or 2 degrees Celsius of warming would be used in the second wave of urbanisation, he said.
"Even before we drive an hour or turn on our electricity for an hour, 75 per cent [of the budget is] already gone just for the need of creating residential and other buildings. And that's often overlooked," Dr Schandl said.
The work on Braddon, published in the Journal of Cleaner Production, showed the carbon dioxide equivalent held in the suburb's buildings was about 282,000 tonnes, about the annual carbon sequestration and storage of between 140,000 and 560,000 hectares of Australian forests.
"Demolition or large-scale refurbishment of pre-1982 buildings in Braddon could result in around 9000 tonnes of CO2e [carbon dioxide equivalent] emissions. Such emissions could have a social cost of around $445,000," the paper said.
"A planning process that takes account of different development scenarios and a good understanding of the environmental merits and impacts of different planning decisions will create very large opportunities for the quality of life and for reducing environmental impacts of cities."
Dr Schandl, who worked with a team of researchers in Canberra and overseas, said there was potential for the ACT to be at the forefront of efforts to create a circular economy in the building industry, recovering material from the demolition process and putting it to use.
By extending the model across the city, planners would be able to assess what recoverable materials were held in different areas and use that to inform planning decisions.
Dr Schandl said when infrastructure was decommissioned - a building redeveloped or a house knocked down - most of the material was thought to be waste.
"But there's so much in there which is still useful and can go back into the economic process. It has quite significant employment implications. And so [Canberra] could be like a laboratory, if you like, for how can you organise urban living in a different way, creating better economic and human well being, with all these additional environmental co-benefits," he said.
Greens assembly member Caroline Le Couteur said the provisions would apply to a small number of applications. "It would be for things which are likely to introduce a large quantity of greenhouse gas emissions so it wouldn't be relevant to your standard house," Ms Le Couteur said.
