In order to compensate for fluctuations in production, electricity generation and consumption must both become more flexible. SINTEG therefore focused particularly on flexibility potentials that have been scarcely used to date, e.g. on the demand side or decentralised generators. This essentially includes all consumers, such as production lines in industry, air conditioning systems in offices or heat pumps in households, but also decentralised electricity generators, e.g. PV systems on building roofs. If successfully put into practice, flexibility potentials can avoid grid bottlenecks. For this so-called grid-serving use, flexibilities can be made available to the grid as a stabilising component, e.g. through existing mechanisms such as the provision of balancing energy or through new concepts investigated in SINTEG, such as flexibility markets. 

These potentials first had to be identified - whether in the industry, commerce or households. From a technical point of view, it is relevant, for example, which technologies can provide power flexibly, how large the power provided is and for how long it remains available. Subsequently, the economic viability of these identified potentials is examined. In addition, it is also important - from an economic perspective - whether new business models can be developed that make the expansion of the existing potential interesting for the providers of flexibility. For this purpose, the provision of flexibility should not be considered in isolation. For example, an installed ICT infrastructure can increase living comfort by switching on the heating on the way home or visualising energy consumption. This also contributes to a higher willingness to pay for corresponding investments.

A higher share of electricity from local energy markets ("green, local electricity") from the neighbourhood can provide additional incentives that decisively promote the potential. 

Using the potential of households

Different flexibility potentials can deliver varied contributions can make an important contribution through their characteristics, advantages and disadvantages. Although individual households, for example, provide less flexibility via a flexible heat supply than energy-intensive and/or large industrial plants, the former are practically available everywhere and could be aggregated. Particularly in the case of local grid bottlenecks, flexibilities could be used at household and building level to compensate for fluctuations directly on site.

However, when it comes to tapping flexibilities from households and neighbourhoods, many challenges still need to be overcome: flexibility potentials are often small in scale, the underlying technologies are at varying stages of development, there are unclear cost structures and actors from different sectors that have to work together to leverage the existing potential.

Consequently, a digitalisation of the infrastructure and plants as well as incentives for households and their willingness to take advantage of corresponding opportunities are necessary. Aggregation at neighbourhood level, as demonstrated in examples from SINTEG, is therefore particularly relevant for the use of flexibility potentials from the heat supply of households.

SINTEG findings on flexible heat supply in neighbourhoods

In order to make the findings of successfully developed concepts in Germany as transferable as possible, various blueprints were developed within the framework of the SINTEG synthesis field Flexibility Potentials and Sector Coupling. They are intended to support users in practice, business leaders and politicians in scaling up and replicating solutions. One of these blueprints deals with the flexibilisation of heat supply in residential neighbourhoods.

Why neighbourhood concepts are needed

Because individual flexibility sources from households are very small in scale, the aggregation of several plants and buildings is crucial for a meaningful grid-serving use.  This is the only way to ensure the availability of relevant services at the right time. Aggregation is possible at different levels - from industrial plants to building complexes.

In neighbourhood development, the aspect of aggregation can already be taken into account. If many households are equipped with the same technology, an ICT infrastructure is already scaled and standardised to a certain extent. This simplifies the networking of systems considerably and also reduces the investment costs. An additional advantage of a central heat supply presents itself as follows: there is no need to network and control individual systems in households, but only a few and more easily accessible heat generators. In addition, residents can play a concrete role within the energy transition, independent of the electricity system, and contribute to a sustainable energy system.

The projects Franklin Quartier Mannheim (new building) by C/sells and Quartier Prenzlauer Berg (existing building) in Berlin by WindNODE are examples of the opportunities for making neighbourhoods more flexible. In both quarters, the central heat supply for several building blocks is provided by an interconnected local heating network. This concept is suitable for both new and existing buildings.

In principle, all electrically operated heat generators, such as large heat pumps, heating rods or flexibly mobile CHP plants, can be used as grid-serving, flexible heat sources. Heating rods were used in the model projects in Mannheim and Berlin. They are the easiest way to make heat generation more flexible. They also have the lowest investment costs and the greatest possible modularity. By using local PV systems to provide the electricity for the heating rods, the share of (local) RE in the heating grid can even increase and at the same time be flexibly fed into the grid or the load can be increased or reduced. However, heating rods are not very efficient in converting electricity to heat compared to other technologies. Large heat pumps as an alternative are a more efficient, but (still) expensive technology. In both neighbourhood concepts, energy management and ICT infrastructure are central. Using past load profiles and weather data, forecasts and optimal schedules for the generation plants are created to ensure an efficient, secure and flexible heat supply.

Example within existing district: Prenzlauer Berg district

Existing neighbourhoods have considerable potential to provide flexibility: With approx. 200 residential units that are centrally supplied by a combined heat and power unit (CHP), a flexibility potential of 34 kW of shiftable electrical load is made possible by the CHP in the Prenzlauer Berg neighbourhood. The power-to-heat elements (heating rods) for water heating provide another 50 kW, which can be expanded to up to 200 kW.

This central heat supply concept is advantageous for providing flexibility, but also for reducing heat consumption. In concrete terms, savings of about 25-30 per cent was achieved through automation and centralisation. This corresponds to average savings of 100 euros per household per year [1]. In addition, the residents benefit from greater thermal comfort in their flats. Such added values are particularly important, as they can significantly increase the economic efficiency as well as the acceptance of ICT infrastructure.

Example within a new building quarter: Franklin Quartier Mannheim

In Mannheim, an entire new building district is being designed for optimised flexibility right from the start: the heating supply to households is actively controlled, charging stations for electric vehicles are networked, the central heat supply is fed with PV and power-to-heat elements - all in order to cover as much of the energy consumption as possible with locally generated renewable energy and to be able to offer flexibilities. The flexibility potential in the neighbourhood is particularly high because the large local heating network serves as a buffer store. It can be operated with a maximum possible temperature difference of 15 Kelvin and thus absorb excess electricity from the grid in the form of heat.

Within households, there are transfer stations that absorb the heat from the heating network, store it temporarily and distribute it throughout the building. These heat exchangers can also be controlled without certified smart meter gateways (SMGW). After all, no data on electricity consumption is transmitted from the building and no access to household appliances in the buildings is required. Instead, the manufacturer of the transfer stations uses an IoT solution to control them.

The central heating rods in the heating network and the PV systems provide a flexible interface between the neighbourhood and the electricity system. Certified gateways are therefore only necessary at these central points in the neighbourhood. This is where flexibility is provided to the grid. It is advantageous if the communication infrastructure within the neighbourhood is operated by the neighbourhood developer, e.g. the local fibre optic network with its own edge servers. In this way, communication with all households is ensured and data protection is maintained.

Flexibilities already make sense today

Centralised heating is a key factor in making the heat supply in a neighbourhood more flexible. SINTEG projects successfully demonstrated that the flexibility potential of the heat generators of hundreds of households can be increased by means of sector coupling. The implementation in the neighbourhood reduces individual efforts, hurdles in the installation of the ICT infrastructure and restrictions in the digital control of different heat generators.

An important finding was that local heating networks, ICT infrastructure and the like already make sense for residents and system operators today, even if there are still no remuneration options for the grid-serving provision of flexibilities. Savings in heating costs, increased comfort and optimisation of self-consumption already justify investments in flexible neighbourhood supply. If technology for an efficient and CO2-neutral heat supply is installed, the supply of flexibility to the grid should also be considered and thus prepared in order to make the best possible use of future revenue opportunities.


"The neighbourhood projects of the SINTEG showcases demonstrated that existing technology makes flexible provision possible. Flexible heating supply in a neighbourhood with standardised components reduces the individual effort of connecting individual systems and thus costs. However, current revenue opportunities for grid-serving flexibility are not sufficient to justify investments in flexible district supply. The focus is therefore on added values such as savings in heating costs, comfort gains, optimisation of consumption in the neighbourhood and the awareness of making a contribution to local sustainable energy supply."

Dr. Karoline Steinbacher, SINTEG subject matter expert

What remains after SINTEG?

Possible hurdles on the way to a regulated, area-wide use of a flexible heating supply for neighbourhoods can be overcome. The SINTEG experience shows that the required infrastructure can theoretically be implemented with today. While heating rods are comparatively easy to regulate, the focus should increasingly lie on large heat pumps in the future. They can significantly increase flexibility potentials and efficiency in heat provision.

To scale up the flexibilisation of heat supply in neighbourhoods, both existing district and local heating networks as well as those to be expanded can be used. If further intelligent, controllable heating networks are being deployed, the heating supply in neighbourhoods can make a substantial contribution to flexibility in the future. Newly emerging potentials must then be integrated into neighbourhood electricity management in the future. Heating supply is only one part of potential flexible loads. Battery storage and electric mobility will likewise play an increasingly important role on the way to flexible neighbourhoods.