Good intentions not enough: do your sums on urban sustainability

Planning new developments for sustainability should reflect the evidence. Fernando de Sousa

It is not surprising that there is plenty of debate about making urban development more sustainable. However, like much of the debate on sustainability in general, there is little or no attempt to define and quantify the meaning of urban sustainability in either technical or economic terms.

This oversight needs to be rectified.

The World Health Organization says world population living in cities and urban environments has now passed 50%. It’s estimated to reach 70% by 2050.

The Food and Agricultural Organization of the UN (FAO) says “water use has been growing at more than twice the rate of the population increase during the last century. In rapidly growing urban centres, water has become a fragile and scarce resource in a competing environment”. While urban use consumes 25% of water in Australia, agriculture and other industries that feed and service them require a lot more water.

The residential sector consumes 12% of Australia’s energy use and generate on average 572kg per capita of municipal waste each year.

Both the government and the private sector are trying to reduce the environmental footprint of our cities and that of future urban developments. However, the evidence on whether these initiatives are worthwhile or not is difficult to verify. Even more importantly, it’s getting harder to predict sustainability in an objective way.

The solutions for sustainability that are both proposed and developed are done so in many cases without due consideration to their technical and economic efficiency. For instance, in Australia we have seen new desalination plants built in all major capitals to provide additional water. This is clearly neither technically nor economically the most efficient way of providing water supplies.

Arguably, new and improved sustainable urban development models for our cities must satisfy technological and economic efficiency principles. That is, they must reduce the physical environmental footprint and do so in a way that is economically efficient.

This entails reducing energy consumption and carbon emissions associated with various energy uses, water demand, waste generation and management and transport services. These improvements must be accompanied by a similar improvement in the socio-economic performance aspects of the development.

To improve the economic efficiency of a development, initially the cost of improving sustainability performance should be less than the costs of the situation that the proposed development is attempting to address. For instance, the costs of building a new piece of infrastructure to reduce congestion should be less than the costs of that congestion,otherwise why build it. Then, if a range of options are available (i.e. building a train line versus improving the road network)in which the benefits exceed the costs, selecting the best option should be based on a range of cost effectiveness measures such as the cost/reduction in congestion or cost/CO2 saved.

Ultimately, prospective investors and owners should also be informed of the technical and economic efficiency of the proposed design in terms of the cost per ton of carbon emissions or kilolitres of water saved. Calculations of these measures have not received sufficient attention in the past.

Assessing performance across all these key sustainability areas is a complex process. Several research efforts are currently underway to develop modern computational tools - Melbourne University’s MUTOPIA© is one of them. Planners can use these to objectively assess how new urban developments will perform in critical areas of sustainability such as energy consumption, requirement for new water supply, waste generation and management, transport services and other key economic and financial measures.

Data availability across all these sustainability streams is significantly lacking and dispersed. Responsibility for data lies across too many agencies, and there’s no clear focus on measuring sustainability performance in new urban undertakings. Tools like MUTOPIA can help to better focus data collection and integrate data that are often dispersed in many jurisdictions.

Some progress in improving sustainability has been made in individual areas like water demand and management options such as recycling, rainfall collection and runoff collection and reuse. But these options can have an increased energy carbon emissions footprint. Knowledge and understanding of these interactions is limited, but it’s also critical for a comprehensive picture of the overall environmental and economic footprint of a new development.

Use of these all encompassing visualisation and modelling tools is still low. Most development projects still rely on generic information, often focused on individual dwellings, rather than a whole-of-development performance process. However, if we are to meet the carbon emission reduction targets set out by the Australian Government, new urban development projects must be informed by objective evidence of the benefits and costs involved. Only this will enable developers, investors and residents to act in a rational manner.