Integrated rehabilitation of reinforced concrete buildings: Combining seismic retrofit by means of low-damage exoskeleton and energy refurbishment using multi-functional prefabricated facade

The European building stock was mostly built before the mid-20th century and is characterized by buildings with high energy demand and high seismic vulnerability. Integrated upgrading interventions are therefore urgently needed for moving towards a more resilient community. In this study, rehabilitation interventions are proposed for reinforced concrete buildings to improve their energy efficiency as well as their structural/seismic performance. An integrated refurbishment aiming at structural, architectural, and energy upgrading is targeted. Energy retrofitting with multifunctional wood-based prefabricated modular facades has been evaluated, as capable of reducing heat consumption by an average of 84 % in different climate zones. More specifically, an exoskeleton system consisting of Prestressed Laminated timber (Pres-Lam) technology is considered, which will act as a structural support-skeleton system for a high-performance “double-skin” solution composed of prefabricated panels. This solution can reduce the seismic risk class in high seismic zones. The seismic-energetic integrated intervention is developed for a representative case study building and evaluated with reference to different climates and seismic zones. Furthermore, a preliminary cost-benefit analysis of the integrated solution has been performed, showing higher benefits when compared to the sole energy retrofit. Specifically, considering the seismic retrofit interventions, the cost analysis pointed out that moving up to higher-use classes results in higher performance and costs. Nevertheless, approximately comparable breakeven times have been obtained in the same seismic region by achieving higher targets. The proposed integrated solution is a promising alternative to demolition and reconstruction, providing a deep energy renovation and structural retrofit, avoiding inevitable waste production, additional energy consumption, and C02 emissions; and allowing for a sustainable renovation of the existing building stock.