Optimal Combined Seismic and Energy Efficiency Retrofitting for Existing Buildings in Italy

A large portion of aging existing buildings are susceptible to significant structural damage during earthquakes and suffer from poor energy performance. When considering how to improve the seismic performance and energy efficiency of these structures, retrofitting has been shown to be a more attractive alternative compared to complete demolition and reconstruction. Not only is retrofitting generally preferable from an economic perspective, but it also typically has lower levels of social and environmental impact as well. Together, these three aspects (economic, social, and environmental) form the so-called three pillars of sustainability. Recently, research efforts have begun to focus on developments in combined and integrated seismic and energy retrofit frameworks and techniques, showing that investing in combined retrofitting schemes is often more cost effective than conducting either energy-efficiency or seismic retrofitting alone. As new national and transnational policies place greater emphasis on the environmental impact of the built environment, it is crucial that combined retrofit schemes be evaluated in a comprehensive manner that allows for the selection of optimal schemes when a range of key sustainability-related decision variables (DVs) are considered. This study investigated the selection of a life cycle assessment (LCA)-based optimal combination of seismic and energy-efficiency retrofit schemes for an existing reinforced concrete case-study building in Italy. The seismic performance of the retrofit schemes was evaluated using detailed nonlinear time-history analysis and the Pacific Earthquake Engineering Research Centre's performance-based earthquake engineering (PEER-PBEE) framework, and the resulting economic costs and environmental impacts were incorporated into the LCA methodology. A detailed energy assessment was performed for each retrofit scheme so that the costs and environmental impacts associated with the operation of the building could be included in the LCA. Subsequently, the characteristics of each retrofit scheme were evaluated for a range of additional DVs, which encompassed the three pillars of sustainability. Finally, a multicriteria decision-making process was used to evaluate the optimal combination of seismic and energy retrofit schemes for several locations exhibiting different combinations of seismicity and climatic conditions. The results of this study provide insight into which combinations of seismic and energy efficiency retrofit measures can produce optimal solutions within the constraints set by decision makers and illustrate how assessments of both seismic and energy retrofit interventions can be implemented in the future. (C) 2022 American Society of Civil Engineers.