La risorsa “costruito” per lo sviluppo delle città:retrofit edilizio e addizione volumetrica.

Decreasing the impact of human activities, and particularly of building construction, on natural ecosystem, means on the one hand to limit the amount of use of resources and on the other, according to environmental, social and economic sustainability, to increase the quality of what you create using these resources and the involved territory. Today the growth of cities tends to be implemented through the transformation of existing buildings, aimed at raising the quality level or transfer new quality to buildings through the integration of new features and new benefits, especially those of energy, in a historical moment in which the challenge is lowering the impact of human actions on natural terrestrial ecosystem. In this context, various European interventions of building transformation and volumetric additions are intended to integrate new features or facilities or to build new housing units in order to provide an economic incentive for upgrading the overall building performance. They include strategies aimed at transforming the urban research for new models of social, economic and environmental impacts, while stimulating innovations in construction technologies, which must satisfy the static constraints, feasibility and appropriateness that building on the existing needs, suggesting new models of cities development. Through a critical reading of these measures, demonstrating the ability to give the city the power "to grow and grow without end" and especially "grow light" (Calvino, 1972) about the impact on the ecosystem, the article aims to highlight the technology and the cultural values of such interventions, analyzing their potential applications in the Italian context.