Modernisation of the residential building stock in Germany: Serial retrofitting as a potential approach

The European Union aims to significantly reduce greenhouse gas emissions in the building sector by 2050, with Germany targeting a climate-neutral residential building stock by 2045. In this context, serial retrofitting, an innovative approach to the energy-efficient modernisation of buildings, is becoming increasingly important. The serial retrofitting approach places particular emphasis on improving the energy efficiency of the building by targeting the building envelope and the building systems technology. The standardisation and prefabrication of construction elements, in conjunction with the optimisation of processes throughout the entire value chain, has the potential to reduce renovation time and costs while achieving high energy efficiency standards such as NetZero. Preliminary market analyses in Germany indicate the presence of further potential for savings through economies of scale and learning effects. Serial retrofitting has seen particular advancement in the context of multi-family houses, which account for approximately 53% of all residential units in Germany. This market segment harbours significant potential, as many of these buildings have inadequate energy efficiency due to their age. The primary stage of the study is to examine the potential offered by serial retrofitting measures, particularly for multi-family houses in Germany, and the energy savings that can be achieved consequently. To this end, relevant data sets are statistically analysed to present initial results on the potential energy savings and the scalability of these measures. The analysis is based on a range of structural, energy-related, and technical parameters, including year of construction, gross floor area, energy efficiency standard, energy source and primary energy consumption. The objective of this study is to statistically evaluate and quantify the potential of serial retrofitting to decarbonise the residential building stock.