Sustainable restoration of post-wwii european reinforced concrete buildings

A new approach for the sustainable restoration of the European RC buildings built after World-War II (about 50% of the existing building stock) is proposed in this paper. An additional exoskeleton targeting architectural restyling, energy efficiency upgrade, and structural and seismic upgrading measures is studied for a holistic renovation of the building stock. A new design is introduced to pursue the targets of sustainability and resilience of the intervention. The solution is carried out from the outside, with reduced impairment of the inhabitants and possible building downtime. Two different structural schemes are investigated: a traditional ‘‘Shear Wall’’ and an innovative ‘‘Shell’’ Solution. In the former, additional shear walls ensure the structural safety, and the new envelope upgrades the energy efficiency. On the contrary, shell solution exploits the shape and the extension of the façade to reduce the dimensions of the structural components and force a new box-structural behaviour. Stresses are reduced to such an extent as to allow for dual use, both energy and structural, of the envelope components. This way, the envelope investigated herein may integrate the energy upgrade technologies and the structural safety systems, requiring a high level of innovation. In the paper focus is made on the sole structural renovation. The effectiveness of the solution is verified for a reference building, in which the engineered external shell is applied to a typical residential building as an alternative to the shear wall solution.