Decarbonization of Heating

Decarbonization of heating is the transition from fossil fuel-based space heating and domestic hot water systems to renewable, low-carbon, and electrified heat sources. It replaces oil, gas, and coal boilers with technologies such as heat pumps, biomass heating, solar thermal systems, geothermal energy, and renewable district heating. In the EU and DACH region, heating decarbonization is now a regulatory, economic, and climate priority because buildings consume a large share of final energy and heating produces a major part of building-related CO2 emissions. This process connects heat generation, primary energy performance, carbon reporting, municipal heat planning, and compliance with frameworks such as the EPBD, GEG/GModG, Austria’s EWG, and EU ETS2.

What is Decarbonization of Heating?

Decarbonization of heating is the process of removing fossil fuel combustion from space heating and domestic hot water generation. It replaces oil, natural gas, and coal-based systems with renewable and low-carbon heat sources. Heat pumps, biomass, solar thermal, geothermal energy, and renewable district heating are the main technologies used to achieve it. In German-language policy and technical literature, the concept appears as Dekarbonisierung der Heizung or Wärmewende (heat transition).

Decarbonization of heating targets the heating sector specifically. It is measured by the CO2 emissions produced per unit of heat delivered, not by total energy consumption alone. A building can lower its energy use without decarbonizing its heat source, and it can decarbonize its heat source without lowering total energy use. The two outcomes are related but distinct, and EU climate policy treats them as separate entities with separate compliance requirements.

What is the Purpose Decarbonization of Heating

The purpose of decarbonization of heating is to eliminate greenhouse gas emissions from the single largest end-use of energy in European buildings. Space heating accounted for 63.5% of final energy consumption in the EU residential sector in 2022, with water heating adding a further 14.9%. Heating is therefore the priority target for building-sector climate policy, ahead of electricity use, lighting, or appliances.

At building level, the purpose is to convert a fossil-dependent heat supply into one based on ambient, renewable, or waste heat, delivered through efficient distribution systems. At market level, the purpose is to shift capital and installation practice away from oil and gas boilers and toward heat pumps, biomass, and renewable district heating, before regulatory deadlines and carbon costs make fossil systems commercially unviable.

The Need for Decarbonization of Heating

Buildings are a structurally significant source of EU emissions, and heating is the dominant driver within that total. Buildings account for around 40% of energy consumption and 35% of CO2 emissions in the EU, and three-quarters of the existing building stock is considered energy inefficient. Without a shift away from fossil heat sources, the EU cannot meet its building-sector climate targets.

Regulation has moved from aspiration to binding obligation across the DACH region and the wider EU. This is the core driver behind why decarbonization of heating is no longer optional for new installations and is becoming unavoidable for existing buildings.

EU level — Energy Performance of Buildings Directive (EPBD, Directive (EU) 2024/1275):

• Since the start of 2025, EU governments may no longer subsidize or incentivize the sale of stand-alone fossil fuel boilers.
• Member states must plan for a phase-out of fossil fuel boilers by 2040, and national building renovation plans must set out concrete measures to reach that goal.
• New public buildings must be zero-emission from 2028, and all new buildings from 2030.

Germany — Gebäudeenergiegesetz (GEG) and the incoming Gebäudemodernisierungsgesetz (GModG):

• Since 1 January 2024, every newly installed heating system in a designated new-build area must run on at least 65% renewable energy. For existing buildings, the same requirement takes effect once municipal heat planning is complete, with binding deadlines for larger and smaller municipalities.
• On 10 July 2026, the German cabinet adopted the Gebäudemodernisierungsgesetz, which is expected to enter into force at the end of July or in early August 2026 and will replace the fixed 65% renewable rule with a gradually rising “Bio-Treppe” renewable-fuel share, reaching at least 60% by 2040. Because this reform was adopted only days before this content was published, the exact terms and effective date should be re-verified against the Bundesgesetzblatt before use in binding guidance.

Austria — Erneuerbares-Wärme-Gesetz (EWG):

• Since 29 February 2024, the EWG bans the installation of fossil-fuel heating systems in new buildings.
• From 2025, defective oil and coal boilers may no longer be replaced on a like-for-like basis with new fossil systems. A full ban on oil and coal heating in existing buildings applies from 2035, and all remaining fossil-fuel heating, including gas, must be replaced by 2040.

Carbon pricing — EU ETS2:

• The EU Emissions Trading System 2 (ETS2), which puts a carbon price on fossil fuels used for heating and road transport, was postponed from 2027 and is now scheduled to become fully operational in 2028. This delay does not remove the underlying obligation; it extends the window in which building owners can decarbonize heat supply before fossil fuel costs rise structurally.

Together, these frameworks mean that decarbonization of heating is driven by three converging forces: a direct ban or phase-out schedule for fossil heat generators, the removal of financial support for new fossil installations, and a rising carbon price on the fuel itself.

Key Features of Decarbonization of Heating

Decarbonization of heating, as an operational process, is defined by six features. Each feature functions as a distinct entity with its own definition, purpose, and outcome.

• Renewable heat sourcing
• Electrification of heat generation
• Primary energy reduction
• Regulatory compliance integration
• Sector coupling and grid interaction
• Emissions monitoring and reporting

Detailed Explanation of Features of Decarbonization of Heating

Renewable Heat Sourcing

Definition: The substitution of a fossil fuel energy carrier with a renewable or ambient energy carrier — air, ground, groundwater, or biomass — as the primary input for heat generation.

Purpose: To remove combustion-based CO2 emissions at the point of heat generation.

Benefit: Heat supply becomes decoupled from fossil fuel price volatility and import dependency.

Example: An oil boiler replaced by an air-to-water heat pump draws its primary energy from ambient air instead of heating oil.

Electrification of Heat Generation

Definition: The conversion of heat generation from direct fuel combustion to electrically driven heat transfer, most commonly through a heat pump’s vapor-compression cycle.

Purpose: To allow heat generation to run on an electricity grid that is itself decarbonizing, rather than on a fuel that remains fossil by nature.

Benefit: As the electricity grid’s renewable share increases, an electrified heating system’s emissions fall automatically, without further equipment changes.

Example: A heat pump connected to a grid with a growing wind and solar share reduces its associated emissions year over year, with no change to the appliance itself.

Primary Energy Reduction

Definition: The reduction of primary energy input required to deliver one unit of usable heat, expressed through the Primary Energy Factor (PEF) of the energy carrier used.

Purpose: To ensure that decarbonization also improves overall system efficiency, rather than simply shifting the emissions source.

Benefit: Lower primary energy demand reduces both operating cost and the building’s calculated energy performance rating.

Example: A heat pump with a seasonal performance factor above 3 delivers three or more units of heat per unit of electricity consumed, lowering the effective primary energy factor of the heating system as a whole. This links directly to the Primary Energy Factor cluster.

Regulatory Compliance Integration

Definition: The alignment of a heating system’s technology choice and documentation with binding national and EU requirements, including EPBD renovation plans, GEG/GModG renewable-share rules, and Austria’s EWG.

Purpose: To secure approvals, subsidies, and legal operating status for the heating system chosen.

Benefit: Compliant systems retain access to public funding and avoid retrofit obligations triggered by non-compliant installations.

Example: A new heating system installed in a German municipality with completed heat planning must meet the applicable renewable-energy share on the date of installation to qualify for subsidy programs.

Sector Coupling and Grid Interaction

Definition: The operational link between a heating system and the wider energy system, allowing heat generation to respond to electricity price signals, grid load, and on-site renewable generation.

Purpose: To use heating system flexibility as a grid-balancing resource while lowering the building’s own electricity cost.

Benefit: Reduced electricity cost during high-price periods and improved self-consumption of on-site photovoltaic generation.

Example: A smart-grid-ready heat pump control system shifts compressor operation and buffer tank charging toward hours of high PV yield or low grid price.

Emissions Monitoring and Reporting

Definition: The measurement and documentation of a building’s heating-related CO2 emissions and carbon footprint over time.

Purpose: To provide the data required for EPBD whole-life carbon reporting, energy performance certificates, and voluntary sustainability disclosure.

Benefit: Verified emissions data supports funding applications, resale value, and portfolio-level ESG reporting for commercial owners.

Example: A building’s annual heating emissions are tracked against its previous fossil-fuel baseline to demonstrate progress toward a renovation plan’s targets. This links directly to the CO2 Emissions and Carbon Footprint clusters.

Types of Decarbonization Pathways

Not every building decarbonizes heat supply the same way. The correct pathway depends on building type, location, and existing infrastructure.

• Heat pump conversion — air-source, ground-source, or water-source heat pumps replace the fossil-fuel generator entirely.
• Hybrid systems — a heat pump is combined with an existing gas or oil boiler, which remains as backup for peak demand or extreme cold.
• District heating decarbonization — an existing fossil-fuel district heating network is converted to renewable or waste-heat sources at the network level, decarbonizing all connected buildings at once.
• Biomass-based heating — wood pellet or wood chip boilers replace fossil boilers where a heat pump is not technically or economically viable.
• Solar thermal integration — solar collectors cover a share of domestic hot water and space heating demand, reducing the load on the primary heat generator.
• Hydrogen-ready and green gas systems — boilers designed to run on biomethane or hydrogen blends. Current renewable gas injection into the grid remains a small fraction of total gas consumption, so this pathway currently has limited near-term availability at scale.

Use Cases

• Residential retrofit — replacing an end-of-life oil or gas boiler with a heat pump ahead of a mandatory renewable-energy share taking effect locally.
• New-build compliance — meeting EPBD zero-emission and national renewable-heat requirements from the design stage, avoiding retrofit cost later.
• Multi-family and commercial buildings — coordinating heating system replacement with municipal heat planning (Kommunale Wärmeplanung) status and tenant cost-allocation rules.
• Municipal heat planning integration — aligning individual building decisions with a community’s designated heat network or renewable-heat zoning.
• Industrial low-temperature process heat — replacing fossil-fired process heating below roughly 100°C with heat pump technology, where process temperature and heat pump output are compatible.

Benefits of Decarbonization of Heating

• Direct emissions reduction at the building level, supporting national and EU climate targets.
• Long-term cost stability, since electrified heat is not exposed to the same price volatility as imported oil and gas, and is shielded from rising carbon costs under ETS2.
• Regulatory compliance and funding access, since compliant systems remain eligible for national subsidy programs in Germany and Austria.
• Improved energy performance rating, since lower primary energy demand improves a building’s energy performance certificate.
• Reduced exposure to fossil fuel supply risk, since renewable and electrified heat sources do not depend on imported combustible fuel.

Selection Criteria

Choosing a decarbonization pathway requires an assessment across the following criteria:

• Building envelope and insulation level — determines the heat load a renewable system must cover.
• Existing heat distribution system — radiators require higher flow temperatures than underfloor heating, which affects heat pump efficiency.
• Local heat planning status — whether a municipality has designated the building’s area for a heat network, which affects which systems qualify under national law.
• Grid connection capacity — the electrical supply must support the additional load of an electrified heating system.
• Funding eligibility — subsidy levels and conditions differ by country, income bracket, and system type.
• Primary energy factor of the chosen carrier — determines the system’s contribution to the building’s overall energy performance rating.

Comparisons

Decarbonization of heating is often confused with energy efficiency. Efficiency reduces the amount of energy a building needs; decarbonization changes the emissions profile of the energy it still uses. A well-insulated building with an oil boiler is efficient but not decarbonized. A poorly insulated building with a heat pump is decarbonized but not yet efficient. The two measures are complementary, and EU policy increasingly requires both together.

Integration with Other Systems

Decarbonization of heating does not operate in isolation. It connects to several adjacent building systems and reporting frameworks:

• Smart grid and PV integration — heat pump control systems, such as iDM Navigator, coordinate heat generation with on-site photovoltaic yield and grid price signals, increasing self-consumption and lowering operating cost.
• Domestic hot water and buffer tank systems — decarbonized heat generation is paired with buffer storage to manage load and maintain hot water availability during peak demand.
• Building envelope renovation — insulation and window upgrades reduce the heat load a renewable system must cover, improving the economics of the chosen pathway.
• EPBD carbon and energy performance reporting — decarbonization outcomes feed directly into a building’s whole-life carbon calculation and energy performance certificate.
• Metering and monitoring systems — ongoing verification of emissions reduction supports both regulatory reporting and building-level cost tracking.

Within the iDM Energiesysteme product range, air-source systems from the AERO line and ground/water-source systems from the TERRA line provide the heat generation component of a decarbonization pathway, while Navigator provides the grid and PV integration layer described above.