Court of Justice of the European Union — OZ (Reference for a preliminary ruling – Energy – Promotion of energy

Decided by

Court of Justice of the European Union

Parties

‘EVN Bulgaria Toplofikatsia’ EAD v. OZ

Decision date

October 23, 2025

Remedy

The Court of Justice ruled on a preliminary reference that EU law allows Member States to allocate internal heating installation costs based on apartment volume even if common areas lack radiators, provided the calculation formulas ensure transparent and accurate accounting of individual consumption.

Appeal

Appeal status not stated

Key holdings

1. Member States must ensure that billing information provided to consumers is accurate and based on actual energy consumption whenever technically possible and economically justified.

   “under Article 10(1) of Directive 2012/27, Member States must ensure that billing information is accurate and based on actual consumption, where this is technically possible and economically justified.” — paragraph 64

2. Member States retain broad discretion when choosing and implementing measures to promote energy efficiency and allocate heating costs in multi-apartment buildings.

   “the Member States enjoy a wide discretion as regards both the choice of appropriate measures to reduce energy consumption and the manner in which they are to be implemented.” — paragraph 52

In plain English

EVN Bulgaria Toplofikatsia EAD, a heating supplier, sued apartment owner OZ in a Bulgarian district court for unpaid heating and hot water bills amounting to 519 leva, plus 78.20 leva in interest, covering the period from 1 May 2018 to 31 October 2020. OZ contested the claim, arguing that the energy company used an unfair administrative formula to allocate heating costs across co-owned building units. OZ claimed the formula charged non-consuming residents for heat used by others and failed to reflect actual energy consumption. The Bulgarian court asked the Court of Justice of the European Union to interpret European Union energy efficiency law. The Court held that European Union law does not prohibit national legislation requiring apartment owners to pay for thermal energy emitted by a building internal distribution system based on apartment volume, even if common staircases or corridors lack radiators. However, the Court ruled that any administrative formula used to allocate heat costs must rely on clear, objective, and substantiated parameters that guarantee transparent and accurate accounting of individual consumption based on actual energy used whenever technically feasible. Because the Bulgarian formula relied on theoretical assumptions and failed to account for actual operational conditions and insulation characteristics, the Court indicated that it appeared to lack the required transparency and accuracy. The decision clarifies that while Member States have flexibility in setting cost allocation rules for shared building heating, consumer billing formulas must remain transparent and reflect real consumption.