GEG — German Building Energy Act (Gebäudeenergiegesetz)

Definition

The German Building Energy Act, GEG for short (Gebäudeenergiegesetz), is the leading federal law on energy efficiency in the building sector in Germany. It came into force in 2020 and replaced the previously parallel frameworks: the Energy Saving Ordinance (EnEV), the Energy Saving Act (EnEG) and the Renewable Energies Heat Act (EEWärmeG). The GEG regulates among other things the minimum energetic requirements for new builds and for major renovations of existing buildings, the obligation to use renewable energies when replacing heating systems, the issuance and presentation of Energy Performance Certificates (Energieausweis), retrofit obligations on change of ownership, and minimum technical requirements for individual components (U-values) and system components. The most recent major update took place in 2024 with the amendment package colloquially referred to as the 'Heating Act'. It tightens requirements for new heating systems — newly installed heating systems must perspectively be operated with at least 65 percent renewable energy, depending on the municipal heat planning at the location.

When is the term used?

The GEG is relevant for almost all construction and renovation projects and on change of ownership. Of particular practical relevance are the retrofit obligations: anyone inheriting or buying an existing building generally has to meet certain energetic minimum standards within two years — for example replacing constant-temperature boilers older than 30 years, insulating the top floor ceiling, or insulating accessible hot water and heating pipes in unheated rooms. When replacing heating systems, the 65 percent renewable energy requirements must also be observed once municipal heat planning takes effect at the location.

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