Questions and answers Municipal heat planning

Municipal heat planning is a strategic planning tool that shows the city of Jena the way to a heat supply free of fossil fuels such as natural gas or oil.

It is therefore a key instrument for shaping the heating transition in our city and achieving a climate-neutral building stock.

The heat planning shows where the expansion of district heating or the construction of new heating networks is being examined and where individual heating systems will also be needed in the future.

The heat planning is not legally binding and does not yet offer any guarantee of expansion or a guaranteed date for heating networks.

The draft of Jena's heat planning has been developed over the past few months together with key players in the city and will be presented to the public for participation in February 2025.

The final plan will then be presented to the city council for approval.

The main objective is to designate heating network areas and areas for decentralized heat supply.

A map shows in which areas of Jena which type of heat supply is recommended. The urban area is divided into sub-areas

• with an existing district heating supply,
• with planned expansion of the district heating network,
• with planned new construction of heating networks and
• with decentralized heat supply, e.g. via heat pumps.

Sub-areas are also identified for which the future type of heat supply has not yet been conclusively determined, for example because hydrogen could be an option (test areas).

This is intended to create planning and investment security for citizens, companies and the city itself. Property owners can thus better plan which energy supply investment is the most economical for them and when. At the same time, heat planning should be ecologically, economically and socially compatible.

All houses on streets where district heating is already available or which are located in the current district heating bylaw area should be connected to the heating network. For buildings located within areas where a new heating network is expected to be built or extended, the supply is deemed to be secured if a heating network operator undertakes to guarantee the connection within ten years. If the heating network operator is obliged to do so, transitional heating systems can be used if the heating system is defective in accordance with Section 71j of the Building Energy Act (GEG). If there is no obligation on the part of a heating network operator, other fulfillment options (e.g. heat pumps) must be used in the event of a heating system defect.

Where it is already foreseeable that no heating network can be expanded, the installation of a decentralized option (e.g. heat pump) can be planned and prepared at an early stage.

The suitability test carried out as part of the heat planning process has not yet produced a clear result for the most suitable type of heat supply for this sub-area. For example, at least two types of supply may be equally suitable in these areas or there is not yet enough reliable information available to allow a final assessment.

For these areas, in-depth neighborhood investigations and feasibility studies will be carried out with increased priority in the course of implementing the heat planning in order to achieve planning certainty regarding the most suitable type of heat supply as quickly as possible.

The conversion of the house to decentralized renewable heat generation is also possible at any time in test areas.

Since January 2024, newly installed heating systems in new construction areas must be powered by at least 65% renewable energy. Existing heating systems may continue to be operated and repaired until the end of 2044.

A transitional period until June 2026 applies to the installation of new heating systems in existing buildings in Jena. Only then must broken oil or gas heating systems be replaced by other, climate-friendly systems.

The following options are available for achieving a 65 percent share of renewable energies in heating:

• Connection to a (district) heating network
• heat pump
• Biomass heating (wood, wood chips and pellets)
• Direct electricity heating (only in well-insulated buildings)
• Heat pumps or solar thermal hybrid heating (heat pump or solar thermal system, combined with an oil or gas-fired (peak load) boiler or with biomass heating)
• Heating based on solar thermal energy (if it covers the entire heating requirement)
• Gas heating that demonstrably uses at least 65% sustainable biomethane, biogenic liquid gas or sustainable hydrogen

However, not all options are equally recommended. Sustainably produced biomass is only available to a limited extent and the costs are therefore relatively high. The same applies to the use of biomethane or hydrogen, for which future availability and costs are still unclear from today's perspective.

Existing heating systems may continue to be repaired and operated in the future.

If they cannot be repaired and must be replaced, there is a transitional period of five years for individual heating systems until the new heating system must meet the requirements of the GEG. When converting a floor heating system into a central heating system, the transition period is 13 years. As a transitional solution, a used gas heating system or rental gas heating system can be installed for the time being, for example.

New gas heating systems may still be installed during the transitional period until 30.06.2026. Although this is permitted by law, it is not recommended either financially or in terms of climate protection. Advice on the economic risks posed by the sharp rise in CO₂ prices is mandatory before installing new fossil fuel heating systems. In addition, an increasing proportion of green gases (e.g. biomethane) must be added to new gas heating systems: 15 percent in 2029, 30 percent in 2035, 60 percent in 2040, 100 percent in 2045.

The easiest way to meet all the legal requirements is to connect to a heating network or use a heat pump outside the heating network expansion areas.

The Federal Subsidy for Efficient Buildings (BEG) provides financial support for both replacing heating systems and connecting to a heating network. New, higher subsidy rates for private individuals and companies have been in place since 2024. The funding is made up of the following components, which can be combined up to a maximum funding level of 70%:

• 30 percent basic subsidy for all residential and non-residential buildings
• 30 percent income-related bonus for owner-occupiers with an annual household income of up to 40,000 euros.
• 20 percent climate speed bonus until 2028, after which it decreases.
• 5 percent innovation bonus for heat pumps that use either a natural refrigerant or geothermal/water/wastewater heat.

There are also low-interest loan offers for replacing heating systems and other efficiency measures.

Further information on federal funding can be found on the Energy Changewebsite of the Federal Ministry of Economics and Climate Protection.

Around 56% of households in Jena are already supplied with district heating. The district heating network is set to be significantly expanded by 2035 and beyond.

The current expansion status can be found on the Stadtwerke website District heating expansion in Jena.

If your house is already in the district heating supply area, you can use a form to register for connection to the supply network without obligation. You can find the application form (PDF) on the page All about your district heating contract of the Stadtwerke Jena Group under the heading "Forms". There you will also find further information on district heating supply in Jena.

When completing the registration form, it is advisable to seek the support of a heating contractor to ensure that your future heating supply is perfectly tailored to your needs.

If you would like to find out more about the benefits and characteristics of district heating, the municipal utilities offer various videos and informationon their website .

The existing district heating network in Jena is to be significantly expanded in the coming years. Detailed information on the planned expansion of the existing district heating network and the construction of new heating networks can be found on the Stadtwerke Jena Groupwebsite .

Stadtwerke Energie Jena-Pößneck has published the current planning status for the district heating expansion on its website. There you can also express your interest in a district heating connection directly using the online form. A digital map and the interested party form can be found on the municipal utilities website for the district heating expansion.

This supports the further planning of the municipal utilities for the district heating expansion and you will be informed directly about further steps in the future.

When connecting to the district heating network, there are costs for the supply line on the one hand and for the house connection, i.e. the route from the supply line to your house, on the other. The costs for the supply line are usually borne by the municipal utilities. The house connection costs are borne in part by the municipal utility company and in part by the subscriber. The distribution of costs depends on many different factors. In addition, connections to heating networks are eligible for subsidies so that the costs can be further reduced. Stadtwerke will be happy to advise you and answer your questions.

Currently, more than 98 percent of district heating in Jena is generated from fossil natural gas. The share of renewable energies in Jena's district heating is set to increase significantly step by step: According to the plans of Stadtwerke Energie Jena-Pößneck, the goal of a climate-neutral district heating supply is to be achieved by 2040 at the latest. To this end, the municipal utilities are planning climate-neutral district heating generation using river, geothermal and solar thermal energy, air heat pumps, power-to-heat and hydrogen.

Further information on this can be found on the municipal utility's heating network strategy page.

Heat pumps differ depending on the type of heat source used. There are air source heat pumps, ground source heat pumps and groundwater heat pumps.

The most common are air-to-water heat pumps, for which there is also a high potential for expansion in Jena. They use the heat from the ambient air to heat the heating water in the building.

Further information can be found in the heat pump knowledge portal of the ThEGA state energy agency.

How environmentally friendly the operation of a heat pump is depends, on the one hand, on how much electricity the system requires to generate a certain amount of heating energy. The indicator for this is the annual coefficient of performance (COP). The higher it is, the more efficiently the heat pump works. On the other hand, it depends on the electricity used to operate the heat pump. The greater the proportion of green electricity from renewable energy sources, the more climate-friendly the operation of the heat pump. In 2023, almost 52% of the electricity consumed in Germany was already covered by renewable energy sources. Ideally, a heat pump should be operated with an inexpensive green electricity tariff. Combining a heat pump with a photovoltaic system can also reduce CO₂ emissions.

The so-called flow temperature is decisive for the efficiency and therefore also for the operating costs of the system. This is the temperature to which the heating water is heated using a heat pump before it is distributed via the heating system. With a maximum flow temperature of up to 55 degrees, an air source heat pump can be operated efficiently throughout the year.

Geothermal or waste water heat pumps can also achieve higher flow temperatures because their heat sources are also higher at low outside temperatures. In order to heat buildings with little or no insulation sufficiently with such flow temperatures, it can often be sufficient to replace individual radiators with ones with a larger surface area and better heat distribution. There are also heat pumps that can be used for individual floors. The best examples are the well-known split air conditioning systems, which are used as air-to-air heat pumps to keep living spaces cozy and warm and can switch directly to the cooling function in summer.

In addition, there are now modern high-temperature heat pumps that can reach flow temperatures of up to 80 degrees. Any house can be heated with these heat pumps and the heating technology can make ecological sense despite compromising on efficiency. For uninsulated buildings with low energy efficiency, hybrid heating systems can also be considered temporarily, in which the heat pump is combined with a gas or oil heating system. Once the building has been insulated, the heat pump can then take over the heat supply alone.

An interactive overview of the types, areas of application, installation and costs of heat pumps as well as an integrated "heat pump check" can be found on the heat pump knowledge portal of the ThEGA state energy agency.

Good examples of the use of heat pumps in existing buildings can be found on the Federal Environment Agency'sportal "So geht's mit Wärmepumpen!".

Information on the range of heat pump heating systems offered by Stadtwerke Energie Jena-Pößneck can be found on their heat pump website.

Gas prices are influenced by a number of cost components.

In addition to wholesale prices for natural gas, which have been subject to considerable fluctuations at a high level in recent years, a rising CO₂ price will lead to further cost increases. In addition, gas network charges are another cost component of the gas price.

Although grid fees are strictly regulated by the regulatory authority, the specific grid fees will also increase if the number of grid customers decreases and purchase volumes fall, as the costs for the reliable operation of the grid infrastructure will have to be spread across fewer grid customers.

According to nationwide climate protection legislation, gas grids will no longer distribute fossil natural gas by 31.12.2044 at the latest.

However, gas grids are expected to be comprehensively decommissioned as early as the 2030s, as it does not make sense to continue operating this fossil energy infrastructure due to the declining number of gas grid customers connected and climate policy requirements.

Stadtwerke Jena Netze has not yet finalized its plans for the future of the gas distribution network in Jena. As soon as concrete findings are available, the municipal utilities will publish them in their customer portal.

Heating buildings with natural gas should therefore only be seen as a temporary solution for the current transition period. Affected property owners should look for another solution as soon as possible, in particular connecting to a (district) heating network, installing a heat pump or, if possible in test areas, switching to hydrogen heating.

Only gas grids that transport and distribute green gases, in particular green hydrogen, will still play a role in the energy system in the future.

Stadtwerke Jena Netze has carried out extensive studies on this, which show that its gas grids are already well equipped for 100 percent hydrogen. In addition, concrete transformation plans from natural gas to hydrogen are underway. The initial focus is on industrial and commercial applications in particular; in test areas, heating residential buildings using green hydrogen is also conceivable in the future, subject to availability.

Further information can be found on the Stadtwerke Jena Netze website.