Adaptability as a multi-scale strategy for the regeneration of the built environment through circular economy perspective

Since its founding documents, sustainability has recognized collective well-being and environmental protection as the key to the development of society and, at the same time, the main challenge in the relationships between human activities and the limited capacity of ecosystems to support them. For a long time, it was believed that natural and anthropic systems responded to perturbations gradually through a slow adaptive process. Today, we know that vulnerability (economic, social, environmental and health) projects us into a condition of sudden discontinuity, unpredictable and uncontrollable immersive events, in which every single fragility is related to the "whole" and every single action produces an eco or a cascading effect on the well-being of users and the health of the planet. The global crisis scenarios, the conditions of uncertainty and reality complexity, the limited resources and the variability of the framework of the needs show the failure of a "rigid" conception-organization of the built environment often forced to reorganize itself as a result of stressful events for reach acceptable levels of efficiency or to show its fragility (seismic, hydro-geological, climatic, social) by undermining the concepts of stability (environmental, economic and social security) we are used to. Precisely in urban areas, a context in which human health-planetary health relationships express their effects more than elsewhere, it is necessary to intercept new solutions and rules to deal with the direct consequences (deterioration of surface materials, structures, reduction of energy performance) and indirect (loss of identity, interruption of socio-economic activities, loss of livability and conditions of well-being) of climate change on urban centres. Although the literature recognizes the need for impact forecasting tools, it appears increasingly important to support strategies aimed at increasing adaptability understood as a characteristic of the designed system that allows its transformation/modification, increasing its performance qualities and its life span useful. In this sense, adaptability is one of the fundamental requisites for a holistic-circular regeneration and redevelopment of neighbourhoods and architectures, conceived as products that are not "disposable" but "error-friendliness" or "prone to error" and structured to "regenerate" following damage or decompensation through actions of transformation, repair, maintenance, reuse, reconditioning, etc.A paradigm shift is needed in the interpretation of adaptive intervention as a "regenerative process", understood not only as a solution for the restoration/maintenance of acceptable performance conditions - in a linear vision of the life cycle of the designed system - but a moment of "reset /restart" in which the action (of transformability, maintainability, replaceability, reversibility, mitigation/compensation, etc.) underlies a set of strategies structured in a circular process (Refuse, Rethink, Reduce, Re-use, Repair, Refurbish, Remanufacture, Repurpose, Recycle, Recover). In this sense, interventions on the built environment constitute an opportunity to lead cities towards an ecological transition, if considered both as adaptive actions of external (environmental, social and economic) and internal vulnerabilities (variability linked to user needs) but also as interferences (of circular micro processes) to the linear process with which cities have been conceived and evolved, to constitute a step towards the creation of a potentially regenerative and resilient built environment. The paper is part of a study on the topic of sustainable regeneration and redevelopment of existing buildings and urban areas. It explores the implications between the need for adaptive regeneration to ensure both the adequate levels of performance and functionality of the space (indoor, outdoor space ) with its components/materials and the equally urgent need to conceive such adaptive actions in a circular way. The collection, review and systematization of the literature and case studies led to the identification of a framework of adaptive/circular strategies at the micro (the single component), meso (the building) and macro (the public space) scales. The strategies were then validated in three social housing districts in three Italian cities.