Methodological issues in evaluating integral sustainable renovations

Ongoing research in Europe related to sustainable renovation mainly focuses on improving the energy performance of buildings. These studies have a limited scope regarding sustainability as operational energy is often the only focus. A screening of current practices in Flanders moreover shows that renovations are often limited to small interventions, whereby a long term vision is missing. We are convinced that a more integral approach is necessary to strive for sustainable renovation. This research aims at supporting the construction sector in the challenge for an increased renovation rate with more in depth transformations of the existing housing stock in Flanders. The objective is moreover to stimulate a transition from energy-focused renovations towards integral sustainable renovations from a life cycle perspective. In this context, the research aims among others at developing a number of affordable and innovative ‘open-renovation-systems’, with the focus on interventions such as splitting, combining, wrapping and extending residential buildings. To compare and analyze these renovation systems, a method to evaluate the environmental and financial impact of the renovation interventions over their whole life cycle is being developed. This evaluation method is based on the LCA (life cycle assessment) and LCC (life cycle costing) methodology. This paper focuses on two methodological issues in evaluating the environmental impact of renovation interventions: the allocation of the environmental impact of existing structures and materials to the life cycle before and after renovation, and the role of the estimation of the building lifespan (before and after renovation) in decision taking. The results of the analyzed case study show that the chosen allocation approach does not influence the overall conclusions regarding renovation or demolition followed by new construction. However, the case study reveals that the estimation of the second building lifespan can affect the results in a significant manner.no issnstatus: publishe