Understanding regional metabolism for a sustainable development of urban systems

Cities are the most complex forms of settlements which man has built in the course of his cultural development. Their ''metabolism'' is connected with the world economy and is run mainly by fossil energy carriers. Up to now there are no validated models for the evaluation of a sustainable development of urban regions. The guidelines for a ''sustainable development'' suggest the reduction of resource consumption. The article is concerned with the problem of how the ''sustainable-development concept'' can be transformed from a global to a regional scale. In urban settlements the strategy of final storage should be applied. By this, the subsystem waste management can be transformed within 10 to 15 years to a ''sustainable status''. With regard to the system ''agronomy'', the article concludes that agriculture in urban systems should focus on food production instead of promoting reduction of food production in favour of energy plants, which is not a suitable strategy. The main problems are the energy carriers. Transformation to a ''sustainable status'' is only possible by a reconstruction of the urban system, i.e. of buildings and the transportation network. The rate determining step in achieving such a status is the change in the fabric of buildings and in the type of transportation networks. The reconstruction of an urban system needs, mainly for economical reasons, a time period of two generations.