The embodied energy of building services can account for a quarter to a third of the total embodied energy of a new building. The lifespan of the building technology used is therefore important, and measures to extend this lifespan are particularly important in the planning phase when renovations are pending. The aim of the project is to identify strategies for extending the lifespan of building technology and to examine their implementation potential on the basis of specific non-residential buildings. By analyzing and applying selected case studies, realistic options for further use or reuse are identified. The savings potential in terms of gray greenhouse gas emissions is quantified. Recommendations will be made for calculating the emissions of building technology systems in view of their effective or extended service life. The findings will be used to estimate the potential of circular building technology with regard to net-zero targets.