Features of stable ecological structures are explored and compared with the characteristics of urban structures. Having a high efficiency in recycling material flows, while exploiting a renewable energy resource (sunlight), such ecosystems represent a good example of natural solution towards self-sustainability. Part of their dynamics could be taken as a reference for the environmental sustainability of anthropic systems. By identifying the standpoint from which the anthropic system differentiates from the natural one, this analysis allows the introduction of a set of ecological metaphors useful to interpret urban environmental inefficiencies and used to suggest possible pathways to cope with such issues. After having introduced a number of urban issues that have the most relevant influence on the sustainability of cities, a refined and enhanced metabolic model (named new urban metabolic model), that takes explicitly into account the role of institutional activities and the possible closure of urban cycles, is deepened to produce a tool for the description and the analysis of environmental dynamics and performances in cities.

In: Clini C., Musu I., Gullino M.L. (eds) Sustainable Development and Environmental Management. Springer, Dordrecht