Germany’s Building Energy Act, known as the Gebäudeenergiegesetz or GEG, sets the energy efficiency and renewable heating rules that apply to every building in the country. Since January 1, 2024, any newly installed heating system must draw at least 65% of its energy from renewable sources, though for most existing buildings that requirement only kicks in once the local municipality finishes its heat plan. The Act also governs insulation standards during renovations and the energy performance certificate you need when selling or renting a property. A reform announced in February 2026 would replace the 65% consumer obligation with a green fuel quota on utilities, but until that becomes law, the current rules stand.
The 65% Renewable Heating Rule
The core obligation sits in § 71 of the GEG: a newly installed heating system must generate at least 65% of its heat from renewable sources. Qualifying technologies include electric heat pumps (air, ground, or water source), solar thermal, geothermal, biomass boilers running on sustainably sourced wood pellets or chips, and green hydrogen or its derivatives produced with carbon-free electricity.
The rule has applied since January 1, 2024, but only immediately to new buildings in designated new development areas. For everything else, timing depends on local heat planning.
If you decide to install a new gas, oil, or biomass system, § 71 paragraph 11 requires you to first complete a mandatory energy consultation. The consultation covers the economic risks of rising CO2 prices and the possible cost of procuring hydrogen in the future. It’s meant to ensure you understand what you’re signing up for before installing a combustion-based system.
When the Rule Applies to Your Building
Outside new development areas, the 65% requirement is tied to municipal heat planning under Germany’s Heat Planning Act (Wärmeplanungsgesetz), which also took effect on January 1, 2024. Every municipality must produce a plan mapping out future heating infrastructure, and the completion deadline for that plan sets the date the GEG rule becomes binding on new installations in existing buildings.
- Cities with more than 100,000 residents: heat plans due by June 30, 2026.
- Municipalities of 100,000 or fewer: heat plans due by June 30, 2028.
If a municipality publishes its plan early, the 65% rule can trigger immediately on publication. A smaller town that finishes ahead of schedule may bring the requirement forward by years.1CA-EED. Heat Planning Law Germany
An existing, functional heating system does not have to be replaced. It can run until the end of its useful life. If a boiler fails after the local deadline has passed, you get a transition period of up to five years to install a compliant replacement, and temporary solutions like portable electric heaters or short-term rental boilers can bridge the gap. The grace period matters most for owners waiting on a district heating connection that isn’t yet operational.
What Happens if You Install a Gas or Oil Boiler Now
If you install a new fossil fuel boiler between January 1, 2024, and the expiration of your local heat planning deadline, you’re not required to hit 65% renewable on day one. Instead you must raise the renewable share of your heating supply on a fixed schedule:
- From 2029: at least 15% renewable energy.
- From 2035: at least 30%.
- From 2040: at least 60%.
- From 2045: 100%.
The 2045 endpoint is absolute. No oil or gas heating system may operate in Germany after December 31, 2044, regardless of when it was installed. A new gas boiler is therefore a depreciating asset with a firm expiration date, and by 2029 it will need to run partly on biomethane or green gas, which currently cost significantly more than natural gas.
Ways to Meet the 65% Requirement
The GEG lists several approved routes to compliance in § 71b through § 71h. The right choice depends on the building’s insulation, its location, and what utility infrastructure is nearby.
- Electric heat pumps are the most common solution for detached and semi-detached homes. Air-source units are the cheapest to install; ground-source systems cost more but perform better, especially in poorly insulated buildings.
- District heating satisfies the requirement automatically, because the utility manages the renewable share for the whole grid. This works best in urban areas where networks already exist or are being built.
- Solar thermal is usually paired with another system rather than used alone. It can cover a large share of hot water demand and supplement space heating in warmer months.
- Biomass boilers using wood pellets or chips qualify but must meet strict particulate limits. They tend to suit rural properties without district heating or a strong grid connection.
- H2-ready gas boilers are designed to run on natural gas now and switch to pure hydrogen later. They only count as compliant if the local grid operator has made a legally binding commitment to supply green hydrogen within a defined timeframe. If that commitment doesn’t materialize, you’ll need to retrofit or replace, which makes this the riskiest option.
- Hybrid systems combine a gas boiler with a heat pump: the heat pump handles the base load and the boiler covers peak demand in the coldest weeks.
Every option requires documentation showing the system reaches 65%. Proof typically comes from manufacturer certifications or a heat load calculation prepared by an authorized engineer, and the owner is responsible for making sure the installer supplies the paperwork.
Subsidies for Compliant Heating Systems
Federal support comes through the Bundesförderung für effiziente Gebäude (BEG). Since January 2024, grants for heating system replacements have been administered by the KfW, Germany’s state-owned development bank, rather than BAFA.
The subsidy stacks in layers:
- A basic subsidy of 30% of eligible investment costs for any qualifying renewable heating system.
- A climate speed bonus of an additional 20 percentage points for owner-occupiers who replace a still-functional fossil fuel system before the legal deadline forces them to. This bonus runs through 2028 and starts phasing down in January 2027.2Clean energy for EU islands. Subsidy Federal Subsidy for Energy Efficient Buildings Single Measures
- An efficiency bonus of 5% for heat pumps that use natural refrigerants or tap geothermal energy.
- An income bonus of 30% for households with taxable annual income below €40,000.
The bonuses are cumulative but capped at 70% of eligible costs. Eligible investment is limited to €30,000 per residential unit in a single-family home, so the largest grant possible is €21,000. Properties with an individual renovation roadmap (individueller Sanierungsfahrplan, or iSFP) from a certified energy advisor can claim eligible costs up to €60,000. Applications must go to the KfW before construction begins, and low-interest loans are available to cover costs above the grant.
Insulation Rules Triggered by Renovation
The GEG regulates more than heating. It also sets minimum thermal performance for the building envelope whenever a major renovation happens. The trigger is the 10% rule: once you renovate more than 10% of any component’s surface area, the entire component must meet a defined thermal transmittance limit (U-value).
Required U-values for common components:
- Exterior walls: 0.28 W/(m²·K).
- Roof: 0.24 W/(m²·K).
- Windows: 1.3 W/(m²·K) for the complete unit, or 1.1 W/(m²·K) for the glazing alone.
These apply regardless of whether the building has already switched to renewable heating. Replacing a handful of windows may seem minor, but if the new units account for more than 10% of the total window area, each one must hit the required U-value. The same logic covers re-rendering exterior walls or re-roofing. Insulation work qualifies for BEG subsidies as an individual measure at 15% of eligible costs, plus 5% when the work follows an iSFP renovation roadmap.
For new residential and non-residential buildings, § 14 also requires proof of summer heat protection, referencing the DIN 4108-2 standard.
Energy Performance Certificate (Energieausweis)
Every building sold or rented out in Germany must have a valid energy performance certificate under §§ 79–88 of the GEG. The certificate gives prospective buyers or tenants a standardized read on the building’s energy efficiency and has to be presented during the sale or rental process.
Two types are available:
- The demand certificate (Bedarfsausweis) is calculated from the building’s physical characteristics, such as wall thickness, window quality, and heating efficiency. It’s the more rigorous option and doesn’t depend on occupant behavior.
- The consumption certificate (Verbrauchsausweis) is based on actual energy use over the past three years. It’s cheaper and simpler but reflects how previous occupants heated the place.
Older residential buildings with fewer than five units built before the 1977 thermal insulation ordinance must use the demand-based certificate. Other buildings can choose. Certificates are valid for ten years unless the property undergoes significant structural changes. Only professionals qualified under § 88 may issue them. Failing to provide a certificate or displaying incorrect data can lead to fines of up to €10,000.3Verwaltungsportal Hessen. Building Energy Act (GEG)
The Proposed 2026 Reform
On February 25, 2026, Germany’s CDU/CSU and SPD coalition published key points for a major overhaul. The 65% requirement on individual heating systems would be dropped entirely, and sections 71 through 71p and § 72 removed under a new Building Modernization Act (Gebäudemodernisierungsgesetz, or GMG).
In place of the consumer mandate, responsibility would shift to energy utilities through a green oil and gas quota. Starting in 2029, utilities would have to ensure at least 10% of the heating fuels they supply are climate-neutral (biomethane, green hydrogen, or bio-oil), with the share rising in later years. Installing new gas or oil boilers would again be permitted, working under that rising quota.
As of early 2026, this is a policy outline, not enacted law. The key points still need to be drafted into a formal bill and approved by the Bundesrat. Until that happens, the existing GEG and its 65% rule remain in force. If you’re deciding on a heating system now, you face genuine uncertainty: a fully renewable system locks in long-term savings and subsidy eligibility, while waiting could bring more flexibility along with more exposure to rising fossil fuel costs. Speaking with a certified energy advisor before committing is the safest step.