Heating law in Germany 2026: what the Building Modernisation Act says
Since 29 July 2026 the German heating law is called the Building Modernisation Act. This page separates what applies, what has been passed and what has only been announced.
Worked through by Radif Partners · Editorial policy · How we calculate
Required share for your new gas boiler
Required from 2030
15 %
| Green gas a year | 2,700 kWh |
| Extra cost at your premium | enter a premium |
Applies to gas, oil and LPG boilers installed after 29 July 2026.
Germany’s "heating law" has been the Building Modernisation Act (Gebäudemodernisierungsgesetz, GModG) since 29 July 2026, published in Federal Law Gazette 2026 I no. 226. It replaces the 2024 version of the Building Energy Act on the points that mattered most to homeowners. The duty to run a new heating system on 65 % renewable energy is gone, as are the replacement duty for boilers after 30 years and the 2044 end date for fossil fuels. Under section 42 owners choose freely among ten options, gas and oil included. Anyone fitting a new gas, oil or LPG system in an existing house must, under section 43, produce at least 10 % of the heat in a climate-friendly way from 2029, rising to 60 % from 2040. A three-family house with 300 m² of floor area can also meet this until 2034 with 9 m² of solar collectors. Further parts take effect on 1 January 2027, 2028 and 2030, mainly for new buildings.
From GEG to GModG: the timeline
| Date | Step | Status |
|---|---|---|
| 13 May 2026 | Cabinet adopts the draft | done |
| 10 July 2026 | Bundestag passes it, Bundesrat consents | done |
| 23 July 2026 | Signed into law | done |
| 28 July 2026 | Published, BGBl. 2026 I Nr. 226 | done |
| 29 July 2026 | Main part in force (articles 1, 5, 6, 8) | law in force |
| 1 January 2027 | Article 2: digital energy certificate, new floor area definition, classes for non-residential buildings | passed |
| 1 January 2028 | Article 3: new public authority buildings zero-emission | passed |
| 1 January 2030 | Article 4: all new buildings zero-emission | passed |
"Heating law" is a nickname. Since 29 July 2026 the official title is the act on saving energy and modernising heat supply in buildings, the Building Modernisation Act for short. It is not a new statute but the 2020 Building Energy Act with a new title and many changes (Federal Law Gazette 2026 I no. 226). Sections can still be looked up at the old address on gesetze-im-internet.de, in German only. What it means for energy certificates and efficiency classes is under Building Energy Act.
What changed compared with 2024
| Topic | GEG until 28 July 2026 | GModG since 29 July 2026 |
|---|---|---|
| New heating system | at least 65 % renewable (s. 71) | free choice of ten options (s. 42) |
| Link to the heat plan | deadlines by municipality size (s. 71(8)) | removed |
| Old boilers | operating ban after 30 years (s. 72) | removed |
| Fossil fuels | end on 31 December 2044 | quota law announced, climate-neutral by 2045 (s. 42a) |
| Biogas share of new gas boilers | 15 % from 2029, 30 % from 2035, 60 % from 2040 | 10 % from 2029, 15 % from 2030, 30 % from 2035, 60 % from 2040 |
| Advice before fitting fossil heating | mandatory (s. 71(11)) | removed |
| CO₂ costs when letting | stage model | new fossil system: split equally from 2028 |
Note the small shift in the biogas steps: the old law wanted 15 % from 2029, the new one starts that year at 10 % and only reaches 15 % in 2030. The final step of 60 % from 2040 is unchanged (section 43 GModG, GEG 2024).
How the staged duty can be met
Section 43 does not prescribe a product. Besides biomethane, bio-oil, biogenic LPG and hydrogen in four colours, the law allows three technical routes. Solar thermal counts as compliance from 2029 to the end of 2034 if the collector area is large enough: 0.04 m² per m² of floor area with up to two homes, so 6 m² for a 150 m² house, and 0.03 m² with more homes, so 9 m² for a three-family house of 300 m². Ventilation with at least 73 per cent heat recovery serving the whole building works the same way over that period. Finally, a hybrid counts as compliance if the heat pump delivers at least 30 % of the boiler output; with six or more homes, the share it really supplies must be proven after 2039. Outside the window up to 2034, a solar system needs proof from a qualified person as soon as more than 15 per cent is to be counted.
Rules for your new gas boiler
Green gas in 2030, at least
15 %
| Installation allowed | yes (section 42 GModG) |
| CO₂ split 50/50 if let | yes |
| Climate neutral by | 2045 |
For gas boilers installed after 29 July 2026.
What stays the same
Many duties of the old law continue: insulating the top floor ceiling and bare pipes after a change of ownership (sections 35 and 69), standards for building parts when they are renewed (section 36 with annex 7), checks and optimisation of heat pumps and older heating systems (sections 60a to 60c), and the energy certificate when selling or letting. The GModG has redrafted the rules on direct electric heating in section 46. Municipal heat planning keeps the deadlines of the Heat Planning Act, but no heating duty depends on it any more (heat planning).
And the grants?
Grants are not in the act but in a separate guideline, which was rewritten at almost the same time: applications from 21 July 2026 get new rates and a cap that falls every six months (KfW 458). A gas or oil boiler is not funded, even though the law allows it again. Landlords will find the new equal split of CO₂ costs in the CO₂ cost allocation act and in the cost split calculator. The consequences for individual systems are covered under gas boilers and oil boilers.