"Societies in their urban (and also non-urban) segments, are extracting materials and energy from their natural environment, processing these flows, eventually accumulating portions of them as stocks and, in the end, deleting them into the environment as wastes, emissions or deliberate discharges. Urban settlements – cities – are a specific type of stocks in the metabolism of societies, and the way these cities are being built and operated has a substantial influence on the quantities and qualities of material and energy flows needed to sustain their existence. In SUME, the urban metabolism shall be understood as a metaphor for our societies’ way of dealing with its natural environment. With global climate change, limited resources and sources of energy, the question of how a healthy level of metabolic exchange with the environment can be achieved is gaining a dramatic new actuality. It is the question of how existing urban areas shall be transformed and new cities or expansions should be planned – to be researched in SUME with a truly comprehensive approach. The concept of urban metabolism, as understood and applied in SUME, will be including all relevant flows (material, energy, waste etc.), and – as link to future planning – consider the influence of the various urban spatial forms and ways of urban restructuring on the levels and qualities of the flows. In order to search for a reduced extraction of resources and energies, new criteria for planning and governing of urban development will be needed. The urban metabolism approach will be tested as a guideline for such knowledge and methodological improvement. As a comprehensive approach, the concept of metabolism also is scrutinizing the effects of investment, asking if an intensified use of flows for the renewal of urban structures will pay off in the future by lowering the levels of material/energy flows over time, thus attempting to make urban metabolisms more sustainable."