Sustainability of Building Stock Rehabilitation: CO 2 e Footprint of Energy Renovation and Seismic Strengthening, a Case Study

For increasing the sustainability of existing building stock, energy renovation programs for existing buildings are being implemented worldwide with the aim of reducing the CO 2 e footprint associated with building operation. In countries with high seismicity, the long-term effectiveness of energy renovation programs is called into question, since a strong earthquake can severely affect existing buildings and compromise the sustainability of the implemented works. As a result, the design of energy renovation programs in seismically active countries must explicitly account for seismic risk. Integrated intervention programs were developed, in which energy renovation measures are implemented simultaneously with seismic strengthening interventions. Romania represents a particular case due to the specificity of the intermediate-depth Vrancea seismic source, which strongly affects more than 60% of the national territory, covering over 120,000 km 2 . Consequently, a large existing building stock is susceptible to seismic damage in the event of a major earthquake. This paper proposes the assessment of the specific CO 2 e footprint of the Romanian residential building stock for the two types of interventions. The results show that preventive seismic strengthening has the lowest CO 2 e footprint when compared to reactive seismic strengthening, the computed values for different scenarios ranging between 6 kg/m 2 and 45 kg/m 2 in case of preventive retrofitting and 23 kg/m 2 to 121 kg/m 2 in case of reactive retrofitting. Energy renovation leads to midrange values of 27 kg/m 2 to 58 kg/m 2 . Nevertheless, all calculated values are significantly lower than the specific CO 2 e footprint associated with new construction, proving the sustainability of existing building stock rehabilitation techniques. The research presented in this paper can be further extended through the implementation of scenario-based analyses concerning the improvement of the existing building stock through seismic strengthening and energy renovation, considering the occurrence of a major earthquake, in order to determine the optimal solution for the implementation of national programs in relation to the assumed objective of reducing CO 2 e emissions at the building stock level.