District heating too expensive? What the CJEU ruling changes for landlords and businesses

The short answer

Anyone who buys district heating as a consumer and has an invalid price adjustment clause in their contract can, since the CJEU ruling of 24 September 2026 (C-900/24), reclaim price increases even if they never objected within three years. For housing companies and businesses the ruling changes little directly; they still have to argue on the basis of the clause itself.

What a kilowatt hour of district heating costs compared with gas, oil and heat pumps is covered in the guide to heat costs per kilowatt hour. This guide is about what you can do against an increase.

What was the three-year rule, and what did the CJEU strike down?

If a price adjustment clause is invalid, a gap opens in the contract: which price applies instead? For years the Federal Court of Justice (Bundesgerichtshof, BGH) filled this gap with the so-called three-year rule (Dreijahreslösung), most recently refining it for district heating on 25 September 2024 (VIII ZR 176/21). In short: anyone who had not challenged price increases within three years of the relevant annual bill had to accept the price reached in this way. An early objection that was then not pursued for years did not help either.

On a reference from the Kammergericht Berlin (Berlin Higher Regional Court), the CJEU rejected this practice for consumer contracts. The effects of an unfair clause must not be preserved to the consumer’s detriment through a deadline. Moreover, the supplier cannot unilaterally replace a clause found to be unfair. This is consistent with § 24(4) AVBFernwärmeV (German district heating supply regulation), under which a price adjustment clause may not be changed unilaterally by public announcement. How the German courts implement the ruling in detail will first be decided by the Kammergericht in the original case.

Who benefits, and who does not?

Customer	Consumer protection from the CJEU ruling?	Remaining lever
Private homeowner	yes	Refund claim without the three-year limit, mind the limitation period
Condominium owners’ association with at least one consumer	yes, treated as a consumer according to BGH VIII ZR 243/13	as above, resolution of the association required
Private landlord of individual flats	case by case: private asset management or commercial activity	have the status clarified by a lawyer
Housing companies, commercial premises, hotels	no, not directly	review the clause under § 24(4) AVBFernwärmeV
Industrial companies	no; under § 1(2) the AVBFernwärmeV does not apply	review the individual contract under general standard-terms law

The practical difference is large. A business with an invalid clause still has a claim. But it still has to deal with the question of which price replaces the clause, and there is no new EU case law on that for it.

What did the Higher Regional Court of Hamm decide against E.ON today?

On 12 October 2026 the Oberlandesgericht Hamm (Higher Regional Court of Hamm) ruled in the group action brought by the Federation of German Consumer Organisations (vzbv) against E.ON Energy Solutions (2 VKl 1/23). The price adjustment clauses are invalid in three supply areas: Erkrath-Hochdahl, Hamburg-Lohbrügge-Nord and Schwalbach-Limes. For the remaining areas covered by the action, the court refused a blanket finding; the vzbv intends to appeal to the Federal Court of Justice on this point. No money is flowing yet: registered consumers can only claim refunds once the judgment is final.

The message for all other district heating customers: invalid clauses are not an exception, but each one has to be checked individually. A judgment for three networks says nothing about the fourth.

How much money is at stake? A worked example

Property: condominium owners’ association with 12 flats, 120,000 kilowatt hours of district heating a year. Current price: 15.6 cents per kilowatt hour gross, the district heating blended price for apartment buildings according to AGFW as at 01.04.2026. Assumptions for the example: the originally agreed price was 10.0 cents; under the three-year rule an intermediate price of 15.0 cents would have become binding; three billing years are not yet time-barred.

Calculation	Difference per kWh	per year	three years
Three-year rule (binding intermediate price 15.0 ct)	0.6 ct	€720	€2,160
After the CJEU ruling (return to contract price 10.0 ct)	5.6 ct	€6,720	€20,160

The figures are assumptions, not a forecast. They show why a review is worthwhile: in the example the amount in dispute is almost ten times as high. But they also show the limit. Under §§ 195, 199 BGB (German Civil Code), claims are generally time-barred after three years, counted from the end of the year in which the claim arose and the customer knew or should have known about it. Anyone who waits loses a billing year every year.

What is changing politically?

On 26 August 2026 the Federal Cabinet adopted key points for a heat network package. They provide for ex-post price supervision by a federal authority, regular disclosure of prices and cost components, a price transparency platform for all heat suppliers and an arbitration body. The AVBFernwärmeV and the FFVAV are to be merged into a new heat network act. There is no draft bill and no date yet. For existing contracts and past bills, the package therefore does not help for the time being.

What owners and businesses should do now

1. Find the contract and the clause: collect the price adjustment clause, price sheets and all annual bills since the start of the contract.
2. Clarify your own status: consumer, condominium owners’ association, landlord or company. Whether the CJEU ruling applies depends on it.
3. Have the clause reviewed: against § 24(4) AVBFernwärmeV, i.e. cost element, market element and complete, comprehensible calculation factors. For larger properties, with a specialist lawyer.
4. Object in writing and pay under reservation: after the CJEU ruling, an objection is no longer a question of deadlines for consumers, but it documents your position and remains important for companies.
5. Keep an eye on the limitation period: every year end can time-bar another billing year. Anyone who wants to secure claims should act before 31.12.2026.
6. For landlords: clarify with your property manager or lawyer how refunds are to be treated in the service charge statement.
7. Put the price itself in context: regardless of the legal dispute, calculate your own blended price per kilowatt hour and compare it with the alternatives. A valid clause can still produce a high price.