City-Level Decoupling-Full Report

requirements of new service behaviours or infrastructure protocols. Finally, what lessons from self-reliant developments can be applied to the reconfiguration of existing city-wide infrastructures?

Rebound effects are the unintended outcomes of investments that result in more efficient use of resources per capita. Such rebound effects could cause TMR per capita to increase because savings may encourage people to buy more goods and services. For example, shifting commuters from a private vehicle transport model to the use of public transport might reduce TMR per commuter, but making mobility more accessible to the poor would increase the number of commuters, and may ultimately increase overall TMR per capita. This would be a positive developmental outcome in developing country cities where private car systems exclude the poor. But a negative outcome in developed country cities would, for example, be energy savings from green buildings being converted into increased consumption of imported luxury foods. A key mechanism to counteract the rebound effect is to link improvements in efficiency to rising eco-taxes that effectively capture the savings for re-investment in public goods rather than allowing savings to be recycled via malls into increased private consumption (a topic addressed by the Decoupling 2 Report). However, rebound effects might also be less of a problem where real incomes are declining due to recession or inflation, which could itself be driven in part by rising resource prices. Along the same lines, if imports into cities are derived from localities that are expected to pay for environmental externalities, then the imports could well be underpriced. This is effectively a subsidy of consumption in the destination city, thus reinforcing the rebound effect. This suggests that the rebound effect cannot be resolved without understanding indirect material flows embodied in regional flows between urban, rural and peri-urban regions and global flows created by trade (which is the subject of a forthcoming International Resource Panel Report). Direct and indirect flows need to be addressed at the urban level, and this may require socio-political changes in the relationships between consuming and producing regions in the interests of better resource management.

7.3 Total material

requirements and rebound effects

Material flow analyses of cities should be more widely promoted. The work by Sabine Barles on Paris can be considered the current gold standard for this purpose. 126 This will complement and extend the kind of global comparative work that has been initiated by MIT. 127 As the understanding of urban metabolism grows, it will become possible to shed much greater light on the Total Material Requirements (TMR) of cities, including both direct and indirect flows. This will reveal how dependent cities are on material imported from other localities within and beyond national boundaries, indicating the environmental impact of cities on other localities. Linking the quantitative approach provided by the material flow analysis with the qualitative social science approaches will: 2) Make it possible to better define targets for action. For instance, the final energy consumption of Paris has been stable for ten years, while its primary energy consumption continues to increase. This means that reducing urban consumption is as important as improving downstream energy supply. 129 Another example is that of food, where indirect flows are much more important than direct ones. 130 3) Show that indirect flows can help assess what is possible to achieve within an intra-urban approach and place the city within the broader system of flows and stakeholders that make it possible for the city to function. 1) Improve the assessment of indirect flows and urban ecological footprints. 128

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