Using advanced spatial planning and urban design software, CSIRO scientists examined six urban development models to evaluate their impact on a city's air quality and the exposure of its population to harmful pollutants.
Urban growth
A CSIRO study titled Reshaping Cities for a More Sustainable Future predicts that if Australia’s cities continue to grow as urban sprawl, in just 10 to 15 years air pollution in our cities will increase as much as 70 per cent compared to 1990 levels.
The cost of air pollution to Australia is already high.
The human health cost is estimated at between A$3 billion and A$5.3 billion every year, and annual damage to materials, property and buildings is between A$3 billion and A$5 billion – one per cent of gross domestic profit (GDP).
Cars are the biggest cause of air pollution.
Because most Australians shun public transport and rely on cars for transport, we are among the highest per capita air polluters in the world.
Because most Australians shun public transport and rely on cars for transport, we are among the highest per capita air polluters in the world.
Urban design exerts a strong impact on a city's air quality and the exposure of its population to harmful pollutants.
The result is cities that, in the long term, are economically and environmentally non-sustainable.
As the pollution increases, the liveability of our cities will worsen.
Futures scenarios
In Australia most people have come to accept urban sprawl and driving long distances to work as a way of life – but this may change due to:
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the threat to oil supply and associated price increases
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the enhanced greenhouse effect
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the threat to human health caused by poor air quality.
The CSIRO study examined several alternative urban forms to evaluate their capacity to minimise both energy consumption and atmospheric pollution, including greenhouse gas emissions.
'Similar enquiries in the past have been based on subjective assessments about city planning having impact on air quality and how energy is consumed,' says Dr Newton.
'But the order of magnitude between different types of city structure has never been evaluated anywhere in the world.'
Integrated land use/transport emissions/airshed models using advanced spatial planning and urban design software assisted researchers in exploring the effects that alternative residential, workplace and transport structures might have on energy consumption and urban air quality up to the year 2011.
Six alternative scenarios of future urban form were examined:
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Business as usual – the extrapolation of current patterns into the future, that is, laissez faire, low density, dispersed
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Compact city – increased population and density of inner suburbs
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Edge city – increased population, housing densities and employment at selected nodes within the city, with increased investment in orbital freeways linking the edge cities
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Corridor city – a focus on growth along linear corridors emanating from the CBD and supported by upgraded public transport infrastructure
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Fringe city – additional growth predominantly on the fringe of the city
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Ultra city – additional growth predominantly in provincial cities within 100 kilometres of a capital city and linked by high-speed rail transport.
These urban configurations (represented in the diagram below) were applied to the city of Melbourne on the basis of a population increase from 2.5 million to 3.0 million by 2011.
Five of the six scenarios for future urban form. | Photochemical smog for each urban configuration. | Fine particle exposure for each urban configuration. |
Other key assumptions included:
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increasing residential density
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a varying ratio of public/private transport
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the full uptake of vehicle emission controls
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increasing telecommuting (working from home) in particular industries.
The results of the urban modelling were dramatic in their impact on urban air quality.
Worst case scenarios
Photochemical smog would:
Particle emissions would:
Towards a sustainable urban future
The report suggests a number of strategies to improve urban air quality.
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Changes to urban planning and public infrastructure: with advances in computer models now emerging, it is possible for government planning agencies to evaluate a range of development futures for a city, and use these outcomes to guide major infrastructure investments and development plans.
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The role of the construction industry: the ‘ecological footprint’ concept should be used as a strategy for both government and the private sector to minimise energy consumption and emissions in the construction, operation and maintenance of buildings. 'It must become part of design thinking,' says Dr Newton. 'Incentives through tax or a star-rating system like the National Home Energy Rating System (NatHERS) or Green Star (LCA Design) would encourage industry to minimise their building footprints.'
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Education of the public: the Australian public must became more aware of air pollution and the impact private transport usage has on the air we breathe. For example, if public transport patronage increased by 45 per cent, there would be a 28 per cent decrease in exposure to photochemical smog.
Find out more about CSIRO's work in integrated water systems.
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