Optimization of Building Envelope and Energy System During Renovation of German Single Family Homes from Different Construction Eras

In the last ten years Germany has met less than half of its renovation quota annually. This study aims to create a roadmap for German renovation by identifying the construction era of single-family homes which has the greatest potential for decarbonization. A design optimization was conducted in which the sizing of 11 degrees of freedom, consisting of the building envelope and energy systems, took place. Then an operation optimization was conducted, which took these system sizes and simulated a year's worth of energy production. Both optimizations sought to minimize the key performance indicators of annual cost and emissions. The two-step optimization process was performed on 11 different construction eras, each iterated thousands of times over until Pareto optimal results were identified. It was found that by spending the same amount of money annually as the business as usual case, the 1949-58 construction era represents the highest potential for improvement. Additionally, if all construction eras are fully renovated from before 1994 over 75 megatons of carbon dioxide emissions could be saved annually. Lastly, the electrification of the energy system and removal of fuel-based energy production was the primary outcome for both the most ecologic and most economic Pareto solutions, across all construction eras