🔥 Energy, CO2 costs and heating
In brief
With gas, oil or liquefied gas heating, tenant and landlord share the CO2 costs. The worse the building, the more you pay.
- You calculate the CO2 emissions in kg per square metre of living space per year.
- Below 12 kg the tenant bears everything; from 52 kg you bear 95 percent.
Since July 2026 the Building Modernisation Act (Gebäudemodernisierungsgesetz) applies; it replaces the Building Energy Act (Gebäudeenergiegesetz). Owners choose their heating freely; the 65 percent rule when replacing a heating system falls away. It is replaced by rising biogas and bio-oil quotas for new gas and oil heating systems: 10 percent from 2029, 15 percent from 2030, 30 percent from 2035, 60 percent from 2040. For tenant protection, §§ 5a and 5b CO2KostAufG regulate the allocation of the operating costs of new gas and oil heating systems.
Step by step
- Determine consumptionUse the fuel bill and the living space.
- Determine the tierMatch the value to the annex of the law.
- AllocateShow the share in the statement.
- Use adviceClarify heating replacement and funding before investing.
Deadlines
- From 32 to under 37 kg, a 50/50 split applies.
- The Gebäudemodernisierungsgesetz inserted §§ 5a and 5b into the CO2KostAufG: cost allocation for installing and operating a heating system under § 43 GModG in existing buildings or new buildings (tenant protection, allocation of the operating costs of new gas and oil heating systems).
- Whether and how the Gebäudemodernisierungsgesetz affects your duties (energy performance certificate, heating replacement) was not checked against the wording.
- The Gebäudemodernisierungsgesetz enters into force in stages: Art. 1 (heating replacement) on 29 July 2026, first rules on the EU Buildings Directive six months later, zero-emission new buildings from 2028 (public authorities) or 2030.
In depth · legal basis, figures and practice – for advisers and professionals
CO2 cost allocation, § 5 CO2KostAufG
The landlord determines the building's CO2 emissions each year in kilograms per square metre of living space per year, rounded to one decimal place, and matches them to the tiered model in the annex. According to the annex, the tenant bears 100 percent below 12 kg and 5 percent from 52 kg; from 32 to under 37 kg both share half each. Different rules apply where a flat has its own separate heat supply and for billing periods under one year.
Gebäudemodernisierungsgesetz 2026
The Gebäudemodernisierungsgesetz was promulgated in BGBl. 2026 Nr. 226 of 28 July 2026 and enters into force in stages: Art. 1 (heating replacement) on 29 July 2026, first rules on the EU Buildings Directive (EPBD) six months later, zero-emission new buildings from 2028 (public authorities) or 2030. It replaces the previous Gebäudeenergiegesetz; owners choose their heating freely, and the mandatory 65 percent renewables rule falls away. Instead, rising biogas and bio-oil quotas apply to new gas and oil heating systems: 10 percent from 2029, 15 percent from 2030, 30 percent from 2035, 60 percent from 2040. For tenant protection, the law inserts §§ 5a and 5b into the CO2KostAufG: they regulate cost allocation for installing and operating a heating system under § 43 GModG in existing buildings or new buildings (allocation of the operating costs of new gas and oil heating systems). The federal funding for efficient buildings (Bundesförderung für effiziente Gebäude) was restated. Details of §§ 5a, 5b CO2KostAufG (size of the shares) and further landlord duties were not checked against the wording.
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