2448588352_df1737f9ecThese transformations are the key to understanding why we need to rethinking the dominant urban model.The question is where to move forward, what is the new urban model to follow. A sustainable urban development goes through some reference criteria. On the one hand, it is necessary for local economic competitiveness policies to be integrated in the long term and oriented towards a systemic vision of cities, placing social cohesion and the right to the city as inalienable objectives, together with the promotion of a model economic and industrial process that is respectful of the environment and that does not make economic progress depend on the increase in the consumption of resources. On the other hand, it is necessary to rethink cities in terms of their scale and structure, because both factors greatly condition the pressures on the environment and the quality of life exerted by buildings, urban planning or urban transport and mobility. This last element is of particular significance. In the last two decades we have witnessed a process of extension of the forms of dispersed urbanization that signify the main pattern of unsustainability of the cities that we have inherited today. This is a pattern that has modified, as we said, both the scale and the structure of our cities, transforming their operation. And, the city understood in metabolic terms, functions as an organism that highly demands resources and generates waste.

In general, a more sustainable city in environmental terms must be able to reduce the consumption of energy and raw materials in typically urban activities (transport, building), integrate respect for the natural environment and the presence of biodiversity within the city itself, minimizing the demand for transport, redirecting expansive land consumption policies, ensuring urban health that eliminates as much as possible the detrimental effects on health of urban functioning and, lastly, organizing adequately the flows of materials with their environment. A city whose design and operation is designed for the people who inhabit it.

Following these general guidelines, in recent times ecocities have appeared as a promise to bring urban sustainability. They are proposed as integral projects for the construction of utopian spaces for the development of new habitable environments that fully comply with the requirements of reducing CO2 emissions (zero emissions), residues (zero waste), etc. They contain an optimistic vision (an urban structure capable of being sustainable by itself and of maintaining a systemic balance in its ecological functioning can be built from its foundations) but also a pessimistic vision (it is impossible to achieve it in the already built city and it is not worth the worth dedicating efforts to resolve the unsustainability of the current urban model).

This is a debate that is urgent; first, because the cranes have stopped and the siren songs of the change in the production model speak of sustainability and the temptation may be to aspire to create newactivity in the construction sector by promoting developments in the form of ex novo ecocities. And, secondly, because what is absolutely urgent is the firm commitment to the rehabilitation of the private housing stock, industrial areas and public facilities and buildings. These eco-cities may have had certain demonstrative value, as pilot experiences for the possibility of applying new technological solutions for heating, insulation and energy consumption systems in buildings, but they are not a generalizable solution. if they are conceived as a new stage of urbanization. In a country where there are thousands of empty homes and incomplete urban developments, no more housing should really be built, at least if we look at objective reasons for the social utility of housing, and any urban development that is justified by its sustainable benefits will be false or, at best, a well-intentioned error. On the other hand, a radical commitment to the comprehensive regeneration of the current urban fabric represents a fantastic opportunity to make the promises of sustainability a reality: to recover the most obsolete housing stock to improve the habitability conditions of the neighborhoods most forgotten of our cities, recover and reuse public spaces to give them meaning in community life, rehabilitate public and private buildings to improve their energy efficiency and that are active in the production of renewable energy, redensify the land already built to avoid occupation of more land, making it a priority for cities to start thinking about making the transition to a post-oil scenario and, finally, activating the commercial uses of historic centers and city neighborhoods are some of the actions that best can help the urban transition.

Image < /a>by pieroflix on Flickr under license CC BY-NC-SA 2.0