Renovate in one step, stepwise, or reconstruct?

The existing building stock is outdated, consumes a lot of energy, and is a major contributor to the global greenhouse gas emissions. Consequently, there is an urgent need for a transition of the existing building stock towards energy and carbon neutral buildings. There are three main pathways that could facilitate this transition: one-step deep energy renovation, step-by-step deep energy renovation, and demolition followed by new build. The importance of a sustainable transition, however, raises the question of how the environmental impact and financial cost of these three main pathways relate for different types of single-family dwellings. Several researchers have already searched for decision-making methods that integrate Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) to assess both environmental impacts and financial costs. However, a systematic comparison of the three pathways is lacking. Moreover, existing standards on how to perform an LCA are very conceptual and too vague to allow for a fair and consistent comparison of the three main pathways. This leaves a lot of freedom to LCA practitioners to make assumptions, implement simplifications and set their own boundary conditions. This can contribute to variations and contradictions in the trade-off between the pathways. This research project, therefore, aims to develop a well-defined and robust methodological LCA framework to compare the three main pathways in a fair and consistent way, provide insight into which pathways are most optimal for different types of single-family dwellings, and determine tipping points in the trade-off between the pathways to define more tangible and general building renovation guidelines