Cradle-to-grave life-cycle assessment within the built environment: Comparison between the refurbishment and the complete reconstruction of an office building in Belgium

In the current context of the necessary sustainability transition of the built environment, it is widely recognized that buildings are a major contributor to the energy consumption of fossil fuels and the emission of CO2. Most of the debates, policies and research are however dedicated to the sole construction of new very efficient (up to zero-energy) building, neglecting the potential of actions on the existing building stock. In this context, we argue that LCA tools are of a huge interest to objectivise the need to refurbish old buildings, in order to increase their energy efficiency and extend their life span, and to compare this strategy to the demolition/reconstruction of buildings. To achieve this aim, this paper aims at updating an existing tool that enables to carry out the life cycle assessment of buildings, by taking into account demolition and construction phases. Then, the tool is applied to one case study of the low-energy refurbishment of a public office building in Brussels, to compare the impacts of the complete demolition followed by a complete reconstruction (rebuild project) to the retrofitting of the existing building (retrofit project). Our main findings confirm the huge impact of the use phase, highlight the impact (energy and CO2 emissions) of the construction and demolition phases and show that the in-depth renovation of this building leads to lower environmental indicators compared to its full reconstruction. The tool and results provided in this paper support the development of policies in favour of the retrofitting of the existing building stock and highlight the importance of including the whole life cycle of the building in the analysis.