Building Modernization Act: Bundesrat deliberates on nearly 70 amendment proposals from the states

In order to nevertheless achieve the climate targets in the building sector, the draft provides for a so-called bio-ladder with four stages up to 2040. Newly installed oil and gas heating systems must, from 2029 onwards, be operated with a growing share of biogenic fuels — i.e., biomethane, bio-oil, biogenic liquefied gas, or hydrogen — in stages. Initially, the mandatory share is to be 10 percent. The target for 2040 is 60 percent. However, new oil and gas heating systems are not to receive state subsidies.

Core rule: Abolition of the 65-percent quota

For tenants, the draft also brings noticeable changes. From 2028 onwards, the costs for the CO2 price and the gas network charges are to be split equally between tenants and landlords. From 2029, landlords will also bear half of the additional costs for the prescribed quota of biogenic fuels.

The resistance to the draft is considerable. A broad majority of the state environment ministers as well as the Climate Union of CDU and CSU also reject the presented draft law. They point out that the agreed climate targets would not be met with the new regulations. However, according to a report by the Funke Mediengruppe, the federal government apparently does not have any robust data on the effects the law would have on CO2 emissions and climate protection overall.

In response to a parliamentary question from the Greens, the federal government stated that a "robust assessment of the climate impact of the law" could only be made "after the completion of the legislative process." According to the report, forecasts on the future price development for natural gas, biomethane, and so-called green hydrogen were also not available to the government. These would also "not be robustly producible." The compatibility of the legislative project with EU law likewise cannot yet be conclusively assessed.

Criticism from states and opposition

Criticism is also coming from the opposition. Bock said: "Es versage beim Klimaschutz, bei der sozialen Gerechtigkeit und bei der Verfassungsmäßigkeit." It also extended the dependence on fossil-fuel heating systems, although operating them was threatening to become unaffordable for many households. Saleh of the Greens said this was unconstitutional because of the prohibition on worsening situations (Article 20a) anchored in the Basic Law for new laws.

Several environmental associations and the Left faction in the Bundestag are considering a lawsuit against the new law. Numerous amendment requests are also coming from the federal states: Overall, nearly 70 amendment proposals from the Bundesrat committees are on the table, which were to be put to a vote on Friday.

Overview of the states' positions

Hamburg's Authority for Urban Development and Housing considers the draft problematic and is concerned about compliance with Hamburg's climate targets. Hamburg's Green-led environment authority has introduced its own motion in the Bundesrat aimed at preserving the operating ban on fossil heating systems from 2045 onwards. Hamburg's urban development authority stated: "Mit der Streichung bisheriger Regelungen zu alten fossilen Heizkesseln verlieren die Länder wichtige Steuerungsmöglichkeiten." The motion also criticizes that the law would place a one-sided and socially unbalanced burden on tenants through rising heating costs. Hamburg is calling for more leeway for state-specific regulations.

Lower Saxony's Green-led Ministry of the Environment supports the motion to preserve the ban on fossil heating systems from 2045 onwards; the SPD-led Ministry of Economics considers achieving the climate targets in the building sector important, but relies more on incentives such as subsidies for heat pumps rather than bans. A unified position of the red-green state government therefore does not yet exist.

Mecklenburg-Vorpommern views the draft more positively: the planned Building Modernization Act is more open to technology and more flexible than the old traffic light Heating Act, the State Chancellery stated. However, some rules in the draft are impractical and partly bureaucratic. The state government, which has no Green coalition partner, considers it right to replace the traffic light government's Heating Act.

Schleswig-Holstein, which is governed by a black-green coalition, considers the planned Building Modernization Act to be wrongly aligned. It slows down the heat transition and extends the dependence on fossil energy imports. In addition, the state shares the concern that there may not be sufficient biomass available to gradually increase the share of climate-neutral fuels.

Outlook: Adoption at the beginning of July

Supporters see it differently: Müller said on Deutschlandfunk that the Building Modernization Act would benefit climate protection. The federal government had not yet conclusively commented on the report when the news was broadcast on 12.06.2026 on Deutschlandfunk.