Life cycle impact analysis of different intervention scenarios for regenerating the existing building heritage. The case study of the new “Borgo Digani” in Argelato, Bologna

This paper aims to compare different intervention scenarios for the regeneration of the existing building stock based on two opposite paradigms: deep renovation and demolition and reconstruction. In the second case, three different construction technologies for the structure of the new building were investigated, respecting the original volumetric and architectural characteristics: wood, reinforced concrete, and steel. The comparison between the different solutions sought to highlight the potential and criticalities of the two different approaches, with particular attention to aspects related to environmental sustainability. This investigation was carried out on a manor villa built at the beginning of the 1990s, belonging to the “Borgo Digani” complex located in Argelato (Bologna), selected as a pilot case by the European project “DRIVE 0”, financed within the Horizon 2020 programme, aiming at promoting the decarbonisation of the existing built heritage. The analysis was carried out by imposing certain fixed conditions for all scenarios: the external shape of the building, the thermal performance of the envelope walls (equal to 0.18 ± 0.02 W/m2K), and the use of the same thermal insulation material for energy efficiency. Analyses of the energy performance of the different technologies adopted and the different building envelope solutions selected were addressed with Edilclima software. The assessments of the environmental impact of the various interventions, on the other hand, were carried out through a simplified Life Cycle Assessment (LCA) on the whole life cycle of the building, using One Click LCA software. The results of the analyses, expressed in terms of embodied energy and embodied carbon, showed how the final values are highly influenced by the imposed boundary conditions and how crucial it is to interpret critically the data resulting from the calculations carried out, which also consider the expected performance.