A multidisciplinary approach in seismic and energy, retrofit of existing RC buildings: A‘’structural double skin’’

In Europe, most of the existing RC buildings were built after the Second World War, which, after more than fifty years of useful life, present problems of seismic vulnerability and severe energy deficits. This study is part of a broader research initiative conducted in Reggio Calabria, aimed at developing an innovative, integrated retrofit strategy. Through a multidisciplinary approach and a holistic vision, the objective is to extend the service life of existing RC buildings by implementing a single, non-invasive intervention that does not disrupt their functionality. In this paper, an integrated retrofit methodology to enhance both seismic and energy performance of RC buildings is presented. The proposed solution involves the addition of a structural "double skin" on the façade, consisting of a steel exoskeleton and a ventilated façade system. The design strategy is illustrated through its application to a case study, where numerical analyses were performed to assess seismic and energy performance. The results demonstrate that the proposed intervention significantly improves the seismic safety indices while generating sufficient energy to meet the building’s operational needs, all achieved through an external façade intervention. A comparative analysis of pre- and post-retrofit conditions confirms the effectiveness of the strategy, highlighting how an integrated "double skin" retrofit can enhance both seismic and energy performance without interrupting building operations. Furthermore, the approach aligns with principles of economic and environmental sustainability, offering a viable solution for upgrading aging RC building stock.