Comparative Life Cycle Assessment of Reconstruction and Renovation for Carbon Reduction in Buildings

This study compares the environmental impacts of building reconstruction and renovation in aging building improvement projects and quantitatively assesses their carbon reduction potential from a life cycle perspective. A life cycle assessment (LCA) methodology was used to estimate greenhouse gas emissions across all stages—production, transportation, construction, operation, and disposal. A reinforced concrete (RC) structure in Seoul served as the case study, with three scenarios modeled: maintaining the existing structure, reconstruction, and renovation. Results show that renovation produced a carbon emission intensity of approximately 1.37 × 103 kg–CO2eq/m2—46.21% lower than the existing building and 22.34% lower than reconstruction. Renovation offered significant embodied carbon savings during the production and demolition phases. In the operational phase, emissions were reduced by 47.50% through upgrades such as high-performance insulation, better windows, and renewable energy systems. While reconstruction showed some emission reductions, its environmental burden remained higher due to the need for new materials and additional demolition waste. Overall, renovation demonstrates greater carbon reduction potential across the building’s life cycle. These findings underscore its value as a key strategy for achieving carbon neutrality in the building sector by 2050 and provide scientific evidence to inform design and policy decisions.