Life cycle assessment of energy renovation versus demolition and new construction in the context of a social housing project

Buildings are a major contributor to environmental impacts and energy consumption within the European Union. Consequently, the EU has established specific targets and policies for improved building energy and environmental performance, with the Renovation Wave being one of the most notable initiatives. However, current strategies mainly focus on energy efficiency in the operational phase of buildings, overlooking the embodied impacts from materials usage during the production, construction and retrofitting phases. Moreover, the emphasis on renovations and the neglect of alternative case entailing building demolition followed by reconstruction could present limitations in decision-making. Few studies provide comprehensive comparative assessment between renovation or reconstruction in a residential context. In the few studies which employ life cycle assessment methodology, the end-of-life stage and the potential benefits from recycling of materials are not considered in the comparison. This study compares the environmental impacts and benefits of different renovation and reconstruction scenarios of a social housing building in Ghent, Belgium, considering the entire building life cycle. The renovation scenarios differ in energy performance levels. While existing studies typically consider static average energy mix, this study performs an analysis to show the sensitivity of the results to the dynamics as well as the evolution of the electricity mix and marginal energy sources. The comparison between renovation and new construction shows a substantial decrease in environmental impact in new construction, with a reduction of up to 92% between analyzed scenarios, attributed to improved energy performance despite increased embodied impacts. Operational emissions remain a significant contributor to total impact across all scenarios, emphasizing the importance of electricity source composition. The findings underscore the effectiveness of more substantial renovation or reconstruction efforts over minimal adaptations, especially in meeting Belgium's environmental targets.