and electricity sectors and the fact that they are embedded in largely the same geographical, political, and societal environments. This observed difference in development pace and the lack of a theoretical explanation for it to date prompted the intellectual challenge of this thesis and motivated the scholarly enquiry behind it.
The German heating systemThe German heating system is dispersed and its decarbonization is crucial if Germany is to meet its emission reduction goals. The German building stock encompasses about 19 million residential and non-residential buildings (DESTATIS, 2019, p. 10). About 15% of all CO2 emissions in Germany can be attributed to heat applications in those buildings (BMWi, 2021, p. 121). This means substantial efforts are required if the German government wants to achieve its target of a de facto climate-neutral building stock in 2050, as proposed in its report on the energy transition concept (BMWi, 2021, p. 51).Buildings in Germany are traditionally heated by coal, heating oil and natural gas. As a result, these fossil fuel technologies still supply heat to more than 80% of German buildings (BDH, 2019). The building stock has not undergone any substantial changes in recent decades (BDH, 2019(BDH, , 2020. Even though there is now a visible shift towards the use of heat pumps in new buildings, which can be powered by using renewable sources of energy, the share of buildings supplied with renewable energy is increasing very slowly due to a low overall renovation rate (BDH, 2020).Technological solutions to provide space heating and warm water based on renewable energy sources have been developed and are widely available, but their diffusion is much slower than the diffusion of renewable electricity innovations. Solutions for single buildings include the use of wood pellets and biogas combustion units, solar thermal appliances, and different heat pump systems, such as air-or water-based systems, either in combination with or without solar PV. Additionally, complementary renewable technology solutions have been developed for heat networks that supply multiple buildings. These run on geothermal or solar thermal heat, waste, biogas, biomass, or large-scale heat pumps. However, even though the German government has implemented substantial financial support schemes to incentivize renewable heat alternatives, in addition to higher insulation standards, these renewable alternatives are diffusing only slowly,
Configurational Innovation Systems
The reason is that, although heat can be physically transported, the associated costs are so high that the transport of heat over distance is not financially viable. Therefore, heat needs to be made available in a building itself or in its immediate vicinity. By contrast, the transmission of electricity is easily and cheaply possible via high-voltage grids with low physical losses. As a result, the provision and consumption of electricity is geographically decoupled. This structural difference leads to a higher context dependency in the heati...