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Reading the Energieausweis: the complete guide for buyers in Germany

Updated: 2026-07-12 · Reading time: 14 min · ImmoLens editorial team

The Energieausweis (energy performance certificate) is the only document in a German listing that puts a number on a building's energy efficiency. That is exactly why it gets misread. It says less than most buyers think, and in other places it says more than the seller would like. This guide explains which type of certificate is mandatory when, why a consumption-based certificate reflects the previous occupants' heating habits, how to turn the efficiency class into a euro figure, and where the certificate systematically misleads.

1. Two types of certificate, and only one is objective

Under § 79 (1) GEG an energy certificate may be issued either as an Energiebedarfsausweis (demand-based) or as an Energieverbrauchsausweis (consumption-based). The difference is not a formality. It decides whether the number on page 1 says something about the building or about the people who lived in it.

The direction of the rule matters. The consumption-based certificate is never mandatory, it is only allowed. What the law prescribes is always the demand-based certificate, in three cases: for a new build (§ 80 (1) GEG), after a major modification with a fresh calculation (§ 80 (2) GEG), and in the case that concerns buyers of older properties.

2. Why the consumption certificate measures the previous occupant

§ 82 GEG requires bills from a consecutive period of 36 months, the most recent of which may not be older than 18 months. Two corrections are prescribed: heating energy consumption is adjusted for the weather, so that a mild winter does not flatter the result, and prolonged vacancy is taken into account in the calculation.

Both of these correct for the weather and for the empty flat. There is no correction for heating behaviour. Someone who keeps the living room at 19 rather than 22 degrees, who never heats the bedrooms, who spends half the year at their children's place: all of that pushes the figure down without adding a single centimetre of insulation. As a rough orientation, building physics assumes that one degree less room temperature cuts heating energy by around six percent. Three degrees of difference in behaviour therefore shift the figure by roughly a fifth, and that is already a full efficiency class.

3. Duty to present, mandatory details in the ad, and the fine

The Energieausweis is not a courtesy of the seller. The GEG regulates the timing and the form:

• No later than the viewing, the seller, landlord or the agent instructed by them must present the certificate or a copy without being asked (§ 80 (4) GEG). If there is no viewing, it must be presented without delay on request.
• Immediately after the contract is concluded, the certificate must be handed over to the buyer. The same applies to letting, leasing and similar arrangements (§ 80 (5) GEG).
• Every commercial property advertisement must contain the mandatory details under § 87 GEG, provided a certificate exists: the type of certificate (demand or consumption), the final energy figure, the main energy source of the heating system, and for residential buildings additionally the year of construction and the energy efficiency class.

4. Validity, exemptions, and who may issue it

Under § 79 (3) GEG an energy certificate is issued for ten years. It loses its validity earlier if a modification to the building makes a new certificate necessary. A certificate from 2015 has therefore expired in 2026, and the seller has to obtain a new one before advertising.

§ 79 (4) GEG names two exemptions: the provisions on the energy certificate do not apply to a small building, and for a listed monument the duties to present and hand over do not apply. Anyone buying a listed building may therefore receive no certificate at all and has to commission the energy assessment themselves.

Only those authorised under § 88 GEG may issue an energy certificate. The section lists the permitted qualifications exhaustively: persons entitled to submit building documents, graduates of relevant degree courses (architecture, civil engineering, physics and related subjects) with further training or professional experience, master craftspeople from the construction, installation and chimney-sweep trades with the corresponding further training, state-recognised technicians, and persons who have passed the energy consultancy examination of the Federal Office for Economic Affairs and Export Control. A pure online provider without those qualifications does not issue a valid certificate.

5. The efficiency classes A+ to H

The classes are set out in Anlage 10 of the GEG. The reference quantity is decisive, and it is almost always misunderstood: the yardstick is the final energy in kilowatt hours per square metre of Gebäudenutzfläche (building usable floor area) per year. Not the primary energy, and not the living area.

The step from class D to class H costs around €2,400 per year in this calculation, so over a 20-year holding period roughly €48,000, with no price increases factored in at all. That is not a minor item, that is a small car every ten years.

6. From the class to the euro figure

The calculation itself is trivial. The errors sit in the two input figures.

Trap 2, the price. The efficiency class says nothing about what the building is heated with, yet it is precisely the energy source that determines the bill. Two houses with an identical figure and an identical class can differ in annual cost by a factor of three:

7. Why a heat pump lifts the class without any insulation

Because Anlage 10 GEG is tied to the final energy and not to the heat demand of the building envelope, replacing the heating system improves the class dramatically even if not a single window has been changed. A heat pump delivers two to four times as much heat as the electricity it consumes. The final energy supplied falls accordingly, and the figure falls with it.

The same terraced house as above, insulation unchanged, only with a different heating system:

8. The CO2 price comes on top

Since 2021 the German national fuel emissions trading scheme has made fossil heat more expensive. § 10 BEHG sets the prices: €25 per tonne of CO2 in 2021, €30 in 2022 and 2023, €45 in 2024, €55 in 2025. For 2026 the fixed-price phase ends. Certificates are auctioned, within a price corridor of €55 to €65 per tonne.

The surcharges are calculated with the usual emission factors of around 0.201 kg CO2 per kilowatt hour of natural gas and around 2.66 kg CO2 per litre of heating oil, each plus 19 percent VAT. For the terraced house in section 6, with 22,620 kWh of gas a year, that is about 4.5 tonnes of CO2 and therefore €300 to €350 in CO2 costs alone, already contained in the gas price. Forecasts beyond 2026 are uncertain: the European emissions trading scheme for buildings and transport is to replace the national system, but the start date and the price mechanism are still being negotiated politically. Only the direction is dependable, not the number.

9. What the Energieausweis does not tell you

This section is the most important one, because it clears up the most common false assumption when buying: the Energieausweis is not a condition report. It does not replace a building surveyor, and it explicitly says nothing about:

• The condition of individual building elements. The certificate makes no statement about whether the roof is watertight, whether the windows still close, or whether the façade has cracks. It works with characteristic values, not with what a surveyor sees.
• Damp, mould, pests. A wet cellar does not appear in the energy certificate. A house in class C can carry €40,000 of cellar damage.
• The quality of the workmanship. Thermal bridges, leaky joints and shoddy work are estimated in a lump-sum way in the demand-based certificate, not measured.
• The consumption you will actually have. The demand-based certificate assumes standardised boundary conditions (room temperature, ventilation, use). Your real consumption regularly deviates from it, in both directions.
• The remaining service life and maintenance state of the heating system. The certificate names the year and the type, but not whether the boiler will fail tomorrow.

10. The six traps when buying

1. A consumption certificate for an unrefurbished pre-war or post-war building. With fewer than five flats and a building application filed before 1 November 1977, it is inadmissible under § 80 (3) GEG unless the house has been brought up to the standard of the 1977 Wärmeschutzverordnung. Ask for proof of that refurbishment if a consumption certificate is presented anyway.
2. Multiplying the figure by the living area. The reference quantity is the Gebäudenutzfläche, which is around a fifth larger. The error makes the heating costs about 20 percent too small.
3. Confusing class with cost. A class E house with night storage heaters costs more than three times a class E house with gas.
4. An expired certificate. Ten years, not a day longer. Check the date of issue on page 1.
5. A good class thanks to a heat pump, and a poor envelope. The class measures the final energy, not the insulation.
6. Reading the certificate as a condition report. It is a calculation sheet, not a survey. For the building fabric you need a separate appointment with a surveyor.

11. Further reading

• Gebäudeenergiegesetz (GEG), full text
• § 10 BEHG, CO2 prices and price corridor
• Destatis, gas and electricity prices for households
• Verbraucherzentrale, the Energieausweis explained