City-Level Decoupling-Full Report

no longer possible for the former to grow and develop at the expense of the latter. Indeed, ‘recoupling' suggests that urban systems need to find ways to develop by restoring their bioregions and the eco-system services they provide to humans and non-humans. 4.2 Adapting the material flow analysis methodology Applying material flow analysis to city-regions requires modifying the framework that is normally adopted at the national and global level. The most sophisticated framework has been developed by Barles based on the Paris city-region. 58 This is described in some detail here because it provides a template for what could be a future global assessment of a broad sample of the world’s cities selected from all regions.

Using standard Eurostat data, Barles has slightly modified material flow analysis in order to develop an approach that is suitable to cities. The difference between countries and cities is that the latter are open systems that will always require sources (of resources) and sinks (for wastes) that are located outside their borders. For example, a substantial proportion of the wastes generated by the city are eventually exported out of the city into the wider region. Reading Figure 4.1 and Table 4.1 together leads to the following conclusions about material flows: • Domestic Material Consumption (DMC) of resources in a city is equal to Domestic Material Input (DMI) minus what is exported out of the system. (DMI comprises both locally extracted and imported materials.) • A proportion of materials that flow into the city accumulate in buildings and infrastructures, referred to as Net Addition

Figure 4.1 Urban material flows 59

INPUT

SOCIETY/ECONOMY

OUTPUT

Balancing inputs

Material accumulation

TMR TMI

Unused local extraction

Balancing outputs

TDO

TMO

Local extraction Emission to air Emission to water Wastes landfilled Dissipative flows

Unused local extraction

DPO

DMO

To nature (local) Emission to air Emission to water Wastes landfilled Dissipative flows

DMI

Material throughput

Imports

To nature (exported

Fossil fuels Raw materials Semi manufactured products Finished products other products Packaging wastes

Emission to air Emission to water Wastes landfilled Dissipative flows

LEPO

Exports except wastes Cf. imports

Exports

Recicling (local+external)

Indirect flow associated with imports

Indirect flows associated with exports

Source: Barles 2009:900

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