Integrating the Energy Performance Gap into Life Cycle Assessments of Building Renovations

The environmental impact of building energy renovation is commonly evaluated through life cycle assessment (LCA). However, existing LCA studies often overlook the energy performance gap—a substantial disparity between calculated and actual energy use—when estimating operational energy use before and after renovation. This paper examines the influence of the energy performance gap on the comparative LCA between unrenovated and renovated buildings. First, a statistical correction model, based on a recent large-scale Flemish study, is developed to correct regulatory calculated energy use for space heating and domestic hot water in a pragmatic way. Subsequently, the model is applied to four single-family dwellings with different energy characteristics that underwent renovation in accordance with Flemish energy regulations. The results show that the anticipated environmental savings over a 60-year study period decrease significantly when the correction model is applied, reducing the estimated savings of 49–80% to 21–49%. Moreover, environmental payback times increase from 2.9–9.1 years to 10.4–22.5 years. Notably, neglecting the energy performance gap in LCAs leads to systematic underestimations of the material use significance. This research underscores the importance of integrating the energy performance gap into LCAs to obtain more accurate estimations of the environmental benefits of energy renovations.