Riqualificare o demolire e ricostruire? Analisi degli scenari progettuali sviluppati secondo un approccio circolare / Renovation or demolition and reconstruction? Analysis of design scenarios developed according to a circular approach

This article deals with the assessment of the environmental impact of two opposite intervention scenarios that can be undertaken when the refurbishment of an existing historical building is needed: deep renovation or demolition and reconstruction? The answer to this question is not simple and should be addressed considering the entire life cycle of the building. Indeed, although a demolition and reconstruction operation, being very invasive, can have a very high environmental impact, it is also true that through a design that follows the principles of sustainability and circularity, this can be lowered by much, making it even the best choice. These two scenarios are compared for a specific case study located in a rural territory in Argelato, near Bologna (Italy), belonging to a historical building complex. The villa has been selected as pilot for the European Horizon 2020 “DRIVE 0” project, whose main objective is to make the renovation of existing buildings more attractive and accessible for promoting a transition to a circular economy. The project of deep renovation of the villa (currently in progress), although designed to limit the environmental impact, was finally conditioned by the historical-documentary constraints that hindered the adoption of the circular approach. In order to have two feasible and comparable options, the reconstruction design scenario followed the same constraints, seeking to increase the degree of circularity of the project where allowed by regulation. For both scenarios, LCA analyses (mainly focused on the envelope) were carried out, and the results were compared, particularly for the impact categories of Global Warming Potential and Total Use of Primary Energy. These analyses have shown that a careful design and study of the demolition process, which tries to maximize the quantities of recycled material, implies that the least impacting scenario – although the most time-consuming and invasive - is that of demolition and reconstruction.