Human Settlements Theme Report
Australia State of the Environment Report 2001 (Theme Report)
Lead Author: Professor Peter W. Newton, CSIRO Building, Construction and Engineering, Authors
Published by CSIRO on behalf of the Department of the Environment and Heritage, 2001
ISBN 0 643 06747 7
Waste, recycling and reuse (continued)
Air pollution and greenhouse (continued)
Urban form and structure has a profound effect on the patterns of travel and energy use of the inhabitants of a city. Governments have a prime responsibility to shape the development and redevelopment of cities according to principles that will provide the greatest opportunity for their long-term economic, environmental and social sustainability.
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Source: Newton (1997).
Our present city forms have created high levels of automobile dependency and use. This, coupled to the age and condition of the vehicle fleet, makes our transport emissions per capita among the highest in the world, more than double those of European cities. Low population density means low emissions per unit area, so Australian airsheds are still relatively clean except on days-meteorologically conducive to pollution.
Hybrid cars have low emissions compared to conventional cars.
Source: Toyota Motor Corporation Australia (2001).
Projected population increases need to be located in an effective way in terms of local amenities, transport and employment. If not, energy use and pollutant emissions will increase disproportionately.
In modelling air quality outcomes for Melbourne in 2011, assuming an additional 0.5 million population, the Inquiry into Urban Air Quality in Australia (AATSE 1997) revealed marked differences in air pollution for alternative scenarios for the placement of this added population. The alternative scenarios were: business-as-usual; corridor city; compact city; multi-model (edge) city; and fringe city (for more details on the study see Newton (1997)). Each scenario represents a relatively extreme possibility, deliberately selected to explore for relative shifts in air quality performance.
Coupling urban form and airshed modelling provided dramatic outcomes in relation to energy use and urban air quality:
- Energy use - daily transport fuel consumption was up to 43% lower for a compact city compared with business as usual. Telecommuting could reduce this even further.
- Photochemical smog - for a high smog day scenario in 2011, photochemical smog levels show a 55% improvement from the present day (base 1990) for the corridor city compared with a 71% increase in pollution levels for business as usual (Figure 88).
- Particulate pollution - for an adverse set of winter conditions resulting in particle build up, there would be a corresponding improvement of 14% for the corridor city and a worsening by 61% for business as usual computed to the 1990 base. The compact city is, for a given emission load, substantially worse than any other.
Figure 88: Effect of urban form on population exposure to photochemical smog in Melbourne on an adverse day; base case (1990) and five archetypal urban development scenarios for 2011.
Source: Newton (1997).
The worst possible scenario, in terms of energy use and total pollutant emissions, is the continuation of current low-density, distributed settlement patterns.
These results show that urban form does matter, and that a laissez-faire approach which continues to create a relatively low-density, dispersed city form with random infill will create and continue to create, suboptimal living and working environments into the future.
Greater consideration needs to be given to issues such as the 'shape' of urban development, improving the integration of transport and land use, minimising the amount of travel required and encouraging higher levels of self-containment. It is here that governments have the prime responsibility to shape the development of cities in ways that will provide greatest opportunity for their long-term economic, environmental and social sustainability.
The introduction of low-emission vehicles into the car fleet will, over time, result in a reduction in pollution levels in Australia's major cities. Congestion and the relative contribution it makes to energy use and air pollution will not be reduced, however, from the introduction of low-emission vehicles.