Municipal heat planning

The roadmap for the heat supply of the future

Idar-Oberstein is planning the heat supply of tomorrow. The aim is to gradually become less dependent on natural gas and heating oil and to achieve climate-neutral heating by 2045.

The city council decided to carry out municipal heat planning on June 25, 2025

What is a municipal heating plan?

The municipal heating plan is a strategic planning instrument for the city. Initially, it is not legally binding, but serves as a guide for the future development of the heat supply.

The aim of the heating plan is to determine the best possible and most economically viable way to achieve a fossil-free and climate-friendly heat supply on site.

However, the heating transition can only succeed together. In the long term, close cooperation with grid operators, energy suppliers, companies and building and apartment owners is required.

By when must a heating plan for Idar-Oberstein be drawn up?

The Heat Planning Act obliges municipalities to draw up a heat plan. Municipalities such as Idar-Oberstein, where 100,000 people or fewer live, must draw up their heating plan by the end of June 30, 2028 at the latest. Municipalities such as Trier, where more than 100,000 people live, have slightly less time: they must draw up their heating plan by the end of June 30, 2026 at the latest.

How does municipal heat planning work?

A municipal heating plan strategically shows how individual areas can be supplied with heat in the future - for example, decentralized via individual systems or piped via a heating network. It also examines how renewable energies and unavoidable waste heat can be used sensibly on site.

Close cooperation between all relevant stakeholder groups is important so that viable statements can be made for the entire urban area. This includes the city administration and politicians as well as grid operators and energy suppliers, companies and local citizens.

The following steps are carried out for a heating plan:

• Inventory analysis: How does Idar-Oberstein heat? Which energy sources are used? How old are buildings and heating systems in Idar-Oberstein?
• Potential analysis: How much energy can be saved through building modernization and more efficient processes in companies? How much heat will Idar-Oberstein need in the future? How much energy can be used from renewable energy sources available in Idar-Oberstein?
• Target scenario: How can Idar-Oberstein's heat supply be shaped in the future and what share do the various renewable energy sources have in this?
• Classification into heat supply areas ("heat plan"): Which areas in Idar-Oberstein are suitable for a centralized or decentralized (e.g. with heat pumps) heat supply?
• Development of an implementation strategy: Which measures can contribute to effective implementation? Which actors in Idar-Oberstein can implement which measures? What structures and cooperation are needed for this?

What is the result of municipal heat planning?

The result of municipal heat planning is a map that shows which areas of the city are suitable for a centralized or decentralized supply. The heating plan uses the terms "heating network area" and "area for decentralized heat supply" for this purpose. It also shows which energy sources can be used for the heat supply of the future. The municipal heating plan thus provides guidance for planning and investment decisions - for example, for homeowners who are about to replace their heating system or carry out similar renovations.

Examples of heat plans that have already been drawn up can be seen in the practical insights provided by the Heat Transition Competence Center.

How binding is a municipal heating plan?

The local authority's heating plan is not legally binding, but merely serves as an informal guideline. The plan can only have a legally binding effect through the designation of "heating network areas" and "hydrogen areas". This requires an additional designation and additional resolution for clearly defined parcels of land in the municipality. By deciding on the areas, early compliance with the Building Energy Act (GEG) follows one month after the announcement, whereby there is still technical freedom of choice to achieve the requirements. The designation of such areas is not part of municipal heat planning. Despite its rather informal character, the heat plan continues to offer added value. It can achieve the following:

• Strategy for a CO2-free, safe and economical heat supply,
• Definition of suitability areas for heating networks and heat pumps
• Prioritization of measures
• Guideline for urban development and urban planning
• Guidance for the expansion of the electricity grid
• Guidance for building families and homeowners
• Guidance for municipal funding programs

Where does a municipal heating plan reach its limits?

A municipal heating plan is drawn up in times of dynamic changes in framework conditions. In this respect, uncertainties regarding energy prices, implementation capacities and funding modalities cannot be completely eliminated. A heating plan also offers no guarantee of expansion for the heating supply areas shown. The provision of energy infrastructures is the responsibility of potential heating service providers; connection and/or deadline guarantees for heating network connections can therefore not be given. Nevertheless, an exchange with the relevant stakeholders is sought during the preparation process in order to prepare appropriate implementation strategies. A heating plan is no substitute for individual building energy advice - this should always be obtained before replacing heating systems or carrying out similar conversions.

What are fossil-free or renewable heat sources?

Fossil-free or renewable heat sources are necessary for a climate-friendly heat supply of the future. Heat from renewable energies is heat from geothermal energy (heat from the ground), environmental heat (air, water or technical processes), waste water, solar thermal systems, biomass, green methane (combustion of biomethane), renewable electricity, heat pumps and green hydrogen. The heat plan shows how much heat from renewable energies Idar-Oberstein will need in the future and where it can come from.

What kind of heating networks are there?

Basically, a heating network describes the distribution of thermal energy (heat) in the form of steam or hot water from a central generation source through a pipe network to several buildings or systems for the use of space heating or hot water.

A distinction can be made between different forms:

There is no legal definition or uniform demarcation values for differentiating between local and district heating. In most cases, this is used to measure the size of the heating network. Local heating networks mainly describe heating networks that are located in connected residential areas and where the pipe length does not exceed one kilometer. District heating networks, on the other hand, extend over entire urban areas. However, the term is often used synonymously.

In addition to the length of the mesh, a distinction can also be made according to the transmission temperature:

• High-temperature networks that transport water vapor well above 100 °C
• warm heating networks that transport water with flow temperatures between 30-70 °C
• Cold heating networks that transport water with flow temperatures of 0-10 °C. This requires a combination with a heat pump, which acts as a heat exchanger upstream of the building to heat the water to the required useful temperature.

What is the Building Energy Act (GEG)?

The Building Energy Act (GEG) is a legal regulation that has been in force since November 1, 2020 and was amended in 2023. It combines the previous provisions of the Energy Saving Ordinance (EnEV), the Energy Saving Act (EnEG) and the Renewable Energies Heat Act (EEWärmeG) into a uniform guideline. The GEG applies to all heated or air-conditioned buildings and mainly specifies requirements for heating technology and thermal insulation standards. The amendment to the GEG comes into force on January 1, 2024. This will introduce the so-called "65% rule", according to which heating systems must be powered by at least 65% renewable energy. The law defines various fulfillment options. These include heating networks, heat pumps and solar thermal energy. The regulations differ depending on whether you are planning a new build or live in an existing building. The GEG is currently (as of spring 2026) about to be amended.

What is the significance of the Heat Planning Act and the Building Energy Act for me as a homeowner?

The entry into force of the Heat Planning Act (WPG) and the amendment to the Building Energy Act (GEG) will have different effects for house and apartment owners and tenants. The legal regulations apply equally to residential and non-residential buildings, such as commercial or office properties.

The law on municipal heat planning does not initially create any additional costs for citizens. As a rule, no new data needs to be collected from owners or tenants in order to draw up the heating plan. The necessary information is already available from energy suppliers, the municipal administration and district chimney sweeps and is evaluated in accordance with data protection regulations.

The Building Energy Act, on the other hand, came into effect on January 1, 2024. The aim is to gradually switch to a fossil-free heat supply. Different transition periods apply under the GEG, depending on whether it is a new building in a new development area or an existing building and new building in an existing area (e.g. gaps between buildings). New buildings erected in gaps between buildings are treated by law in the same way as existing buildings. At the same time, these transitional periods are directly related to the time horizons of municipal heat planning.

Figure 1 Overview diagram: This applies to new and existing buildings

Source: Federal Ministry for Economic Affairs and Energy, last accessed at https://www.energiewechsel.de/KAENEF/Redaktion/DE/PDF-Anlagen/Infografiken/infografik-geg-2024-neubau-bestandsbau-pdf.html on 24.02.2026.

I am planning a new building and am submitting my building application after January 1, 2024 - what does this mean for me now?

For citizens planning a new build (in a new development area), the Building Energy Act (GEG) imposes new requirements for building insulation and the planned heating system. In a designated new development area, the compliance options under Section 71 GEG (requirements of the 65% regulation) will apply from January 1, 2024. The law provides for a total of seven compliance options, including connection to a heating network, a heat pump, direct electricity heating (only in well-insulated buildings) and biomass heating (wood, wood chips and pellets), Hybrid systems such as heat pump 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 this covers the entire heating requirement), gas heating that demonstrably uses at least 65% biomethane or biogenic liquid gas.

I am building in a gap site - what applies to me now?

If you are planning a new building in an existing area, i.e. in a building gap, the same transitional periods apply to you as for an existing building. The 65% rule therefore only applies to newly installed heating systems as soon as the heating plan is available. Until the heating plan is available, it is still possible to install gas heating systems, provided they can be converted to hydrogen at a later date. From January 1, 2024, however, a consultation is required at the time of installation to provide information about the rising costs. In the event of a defect or a planned replacement, homeowners have a transitional period of 5 years to install a new heating system with a 65% share of renewable energy. In the meantime, the installation of a used or borrowed heating system, for example, is permitted. However, it is advisable to find out about the status of municipal heating planning at an early stage and include this in the decision.

How do I know which new heating system is the best option for me?

Which of the compliance options under the Building Energy Act is best suited to your building can ideally be discussed in a personal consultation with certified energy consultants. In some cases, consultations can be funded by the Federal Ministry of Economics and Climate Protection (BMWK). You can find information here: https://www.energie-effizienz-experten.de/

At the same time, a municipal heating plan can be used to determine whether the area in which your building is located is suitable for a heating network. As long as this has not yet been completed, you can access advice from the consumer advice center and use the BMWK heating guide.

I live in an existing building and my heating works, do I now have to buy a heat pump?

No, for citizens with an existing building with a functioning heating system, the Building Energy Act will not initially have any consequences. A functioning fossil fuel heating system that was installed after January 1, 1991 and before January 1, 2024 can continue to be used until the end of December 31, 2044. If the burner system is defective but can be made functional again by repair, it does not need to be replaced.

If the system breaks down and a new system has to be installed (so-called heating breakdown), transitional periods of up to 5 years apply in order to install a heating system that uses at least 65% renewable energy. As long as no concrete specifications from the municipal heating plan apply to an area, the choice of a suitable heating solution is generally the responsibility of the owner.

Only when binding area designations are made at a later date can further requirements result from this. If the city of Idar-Oberstein makes a decision on the designation of an area for the construction or expansion of a heating network or as a hydrogen network expansion area on the basis of a heating plan before June 30, 2028, the requirements of the Building Energy Act will be triggered early.

Important: It is about the installation of a new heating system. At the same time, a heating plan alone does not trigger the obligation. Rather, it requires a municipal announcement of the designation as an area for the construction or expansion of a heating network or as a hydrogen network expansion area. The obligations under the Building Energy Act must be complied with one month after the area designation has been announced.

I have a very old heating system, what do I need to consider?

If a fossil-fuel boiler (natural gas or heating oil) was installed before January 1, 1991, it may no longer be operated. Boilers installed and set up after January 1, 1991 may no longer be operated after 30 years. There are a few exceptions for low-temperature boilers and condensing boilers as well as for heating systems with a nominal output of less than 4 or more than 400 kilowatts.

There is also an exception for owners of detached and semi-detached houses who have only occupied the building themselves since February 1, 2002. In the event of a change of ownership, the acquiring persons are obliged to decommission the boiler no later than two years after the transfer of ownership.

My house is in an area that is suitable for the construction of a new heating network - what now?

The municipal heating plan indicates which areas are suitable for a centralized or decentralized heat supply, particularly from a technical perspective. If a building is located in an area suitable for a central heating network, it is likely that a central heating network will be built there in the future. However, there is no guarantee of expansion or connection, as there is no obligation to build or use a heating infrastructure. A further municipal decision would have to be made for this. The following steps make sense as soon as the heating plan for Idar-Oberstein is available:

• Inquiry to the city regarding the current status of planning and information on whether and when a central heating network can be expected.
• Use of advisory services on the current heating situation (What transitional options are available until the heating network is realized? What alternative decentralized heat supply (e.g. a heat pump) is possible?)
• Taking advantage of consulting opportunities for energy-efficient building modernization in order to save heating costs today and enable new heating technologies in the future.

What impact does a heating system replacement have on my rent?

Landlords can pass on the costs incurred when modernizing the heating system to the tenants. The Building Energy Act and an amendment to the German Civil Code provide for a cap: a maximum of 0.50 euros/m² may be passed on. This cap relates exclusively to the modernization of the heating system. If further modernization measures are carried out, the rent can increase by a maximum of 3 euros/m² within six years.