We recycle things that are subject to a life cycle. Parts of cities, objects, materials: talking about the city as something that can be recycled makes us think about its rhythms, life cycles, metamorphoses. Recycling is not just reusing, but, if we follow the analogy with the organic world, it puts forward a new life cycle. If, beyond the contradictory and short-term outcomes of many interventions, we accept the idea that the city is a resource and that it can be recycled in parts or episodes or as a whole at the end of the different life cycles, then the cities in their making and unmaking are "renewable resources," and recycling cities is an essential strategy that cuts across the scales and themes of the contemporary urban question: the environmental crisis and evermore frequent extreme phenomena, the progressive divide between rich and poor, forced or denied mobility that points towards new exclusions.
Recycle and energy
In a period of energy scarcity, embodied energy becomes an important factor to be considered and should be preserved as much as possible. Recycling allows saving a considerable part of the embodied energy. For a house, if one considers the energy required for the production, use and (eventually) the demolition, it is often much more efficient to recover the existing buildings, rather than demolish and rebuild them. Compared to the processes of urban renewal or urban regeneration, recycling focuses on the physical stratification of what exists. However, a recycling process has a cost, both from an energetic and economic point of view. Therefore reuse and adaptation are worthy when they are given a new ecological, economic, historical value. The starting of a recycling process requires a specific demand and needs the conditions for a new life cycle. Making hypothesis in regard to such conditions allows more precise definition of which building or portions of land may be suitable for a recycling project.
How the diffuse city changes (in the Veneto region)
Over the past twenty years, the diffuse city has changed a lot. Before this period it was made mainly by filaments along the streets, isolated houses with gardens, small and medium-sized warehouse, built along the main axis. More recently the tissue has been densified by the addition of small apartment buildings, row houses, new industrial areas, parking, pedestrian routes, new public spaces and gardens. Over the past two decades these new settlements have grown within the small and medium urban centres, making them more compact and fully exploiting the existing facilities and services. The diffuse city has been densified especially in these centres, while the less dense part has not changed too much. A reflection about recycling must reconsider the patterns of spatial distribution, not only in relation to environmental issues, but also in regard to the dynamics of territorial transformations.
