Evaluating the Environmental Impact of Building Renovation Depth: A Danish Perspective

The construction industry accounts for a significant share of CO2 emissions in Europe and Denmark. Renovation can reduce these emissions since it is significantly less carbon-intensive than new construction. Denmark uses life-cycle assessment (LCA) to evaluate the climate impact of construction, but lacks standard mandates for renovation, leading to inconsistent LCA approaches. This research examines LCA methodologies for building renovations in Denmark, developing a tailored approach that draws on existing approaches outlined in the Danish Building Regulations and various reports from both private and public entities. It assesses different renovation depths (minor, moderate, deep) and preservation interventions. A case study of an actual renovation project in Denmark is used to analyse the energy and environmental impacts. The results indicate that LCAs for minor renovations are not methodologically viable due to their limited scope. In contrast, LCAs of moderate and extensive renovations yield meaningful insights, showing potential reductions of over 50% in energy use and 20–50% variations in overall CO2 emissions across scenarios. In addition, it is observed that energy renovations (i.e., adopting measures to improve the energy efficiency of buildings, especially in moderate and deep renovations) can reach a point at which further improvements do not significantly reduce emissions. Future research should expand LCA applications to a broader range of renovation cases and refine standardised methodologies. Additionally, studies should investigate climate benchmarks and incorporate social and economic factors shaping renovation decisions.