Integrated Approach to Assess the Energy and Environmental Payback Time of Buildings Refurbishment: A Case Study

The design of nZEB buildings, as well as the implementation of retrofit interventions in existing structures, are essential tools for reducing energy consumption in buildings and increasing decarbonization of the building sector. To describe the effectiveness of a retrofit intervention, in addition to the analysis of the benefits in terms of costs and energy savings, an environmental analysis should also be performed, introducing various indicators, such as energy and environmental payback times. In this article, we considered a residential building located in Montemarcello (Liguria, North-west of Italy) that had been subjected to a refurbishment and an expansion, with the aim of evaluating the energy and carbon savings achievable due to the interventions carried out. The life cycle analysis approach was applied to calculate the environmental payback times. The main purpose of this work is the application of an integrated approach to assess the economic, energetic and environmental convenience of retrofit interventions during the entire life cycle of the building, underlining the importance of considering LCA and environmental aspects to achieve decarbonisation of the construction sector. The results show that energy and environmental payback times are lower than the useful life of the building and of its components, and that LCA proves to be a strategic methodology for studying the problems deriving from global warming and energy supply in the building sector.