The expansion of renewable energies requires increasingly flexible, complementary power generation as well as flexibilisation of the electricity demand from consumers. In addition to traditional electricity-to-electricity storage systems and flexible power plants, buildings can also play an important role in shifting electricity demand.

As Germany‘s energy provision will in future be largely based on solar and wind energy, which are not available on call, new concepts must be developed to ensure security of supply and grid stability. At the same time, a future climate-neutral building stock will play a key role in the German government‘s concepts for climate protection. This is because the building sector as a major energy consumer in the German energy system can make a significant contribution to ensuring greater flexibility and gridsupportive consumption behaviour by enabling buildings and districts to act as dispatchable loads, electricity storage systems or decentralised generators. Selectively changing their temporal electricity consumption and injection profile enables buildings to support load smoothing and load shifting. Buildings have a large thermal storage capacity in the form of hot and cold water storage systems and the building mass itself.

Therefore, by coupling them with electricity-based technologies for supplying heating and cooling capacities such as heat pumps and chillers, surplus electricity can be converted into thermal energy or, when there is additional demand, decentralised combined heat and power plants can be operated.

Grid-supportiveness is thus an additional requirement for buildings and districts of the future – in addition to energy and cost efficiency, ecology and user comfort. This Themeninfo brochure defines in detail how grid-supportiveness can be quantified as well as how grid requirements can be modelled in reference variables and taken into account in innovative, grid-responsive control concepts. This information is drawn from the joint “Grid Responsive Buildings” research project that was funded by the German Federal Ministry for Economic Affairs and Energy as part of the “EnOB – Research for Energy-Optimized Building” and “EnEff:Stadt – Research for the Energy Efficient City” research initiatives. The Themeninfo brochure provides insights into current debates and research.

By 2050, it is planned that Germany‘s greenhouse gas emissions should be at least 80 per cent, and if possible 95 per cent lower than 1990 levels. Energy-related CO₂ emissions make up the largest share, at 85 per cent. In order to achieve its climate protection goals in the energy supply sector, the German government has decided to drive forward the Energiewende – Germany‘s energy transition. This requires a fundamental transformation of today‘s energy provision. This raises the important question as to what a cost-optimal transformation of the German energy system will look like, including all energy sources and all consumption sectors.

Techno-economic energy system models can help identify and evaluate optimal paths for transforming the German energy system. These models illustrate the interaction between the different sectors of the energy system, such as private households, trade-commerce services, industry, transport and agriculture. And this in turn enables scenarios to be derived for expanding and developing the future energy system. The Renewable Energy Model-Deutschland (REMod-D) was developed by Fraunhofer ISE to calculate technically and economically feasible transformation paths for the German energy system from today until 2050. The goal: To comply with the German government‘ s climate protection goals, ensure security of supply at all times and minimise the total costs for the energy system.

REMod-D enables the entire energy supply to be modelled at hourly intervals, including all consumption sectors, power generation and storage. The model maps the entire energy system with its dependencies, energy flows and temporal fluctuations of the energy supply and demand, whereby the energy-related CO₂ emissions from the entire energy system should not exceed a given target path. In addition to conventional power plants, renewable energies are also used to provide electricity and heat. The scenarios investigated differ with regard to the drive concepts used for future mobility, the extent of the energy-efficient refurbishment of buildings and the point in time when the use of coal is phased out for power generation.