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Energy certificate and renovation duties when buying a house

The energy certificate shows how much energy a building needs or has used. What it does not show you check at the viewing. Both belong in the price.

Nationwide address search. Which data appears depends on each state’s sources.

Duty to show the certificate

Seller or broker must show prospective buyers the energy certificate or a copy at the latest at the viewing; a clearly visible display is enough. After the purchase contract it must be handed over without delay (sec. 80 (4) GModG). Listings must contain mandatory details from it (sec. 87 GModG). Breaches are administrative offences with fines of up to €10,000 (sec. 108 GModG).

Consumption vs. demand certificate

Two kinds of energy certificate
Consumption-basedDemand-based
BasisMeasured consumption of occupantsCalculation from building parts and systems
Depends onBehaviour, vacancy, weatherThe building, not the occupants
Use when buyingHint at real costs of previous ownersBetter comparable between buildings

Retrofit duties after a change of owner

Until a change in the law, new owners of one- and two-family houses had to carry out certain retrofits within a deadline, such as insulating the top floor ceiling or replacing very old boilers. In the version currently published on gesetze-im-internet.de, where the law is titled GModG, these provisions (secs. 47 and 72 to 73) are marked as repealed.

Estimating condition: year, heating, roof

Many condition questions can be read from the year of each component: roof, heating, windows. The property file shows building and roof data from official 3D models where available; condition itself is only visible on site.

Visible in the filewhere official data exists

  • Footprint and height from official 3D models, where available
  • Roof areas and orientation
  • Solar potential as a range

Obtain elsewherefrom seller, notary or authority

  • Energy certificate (seller)
  • Year of heating, roof and windows
  • Damp, pipes, wiring (viewing)
  • Quotes for renovation

If you cannot attend the inspection yourself, the guide for buyers based outside Germany helps you plan local support and keep the findings in your purchase file.

Frequently asked questions

How long is an energy certificate valid?

Ten years from issue (sec. 79 GModG).

Do I have to replace the boiler after buying?

The former replacement duty for old boilers after a change of owner is marked as repealed in the currently published GModG (status 2 Oct 2026). Whether replacing it soon makes sense depends on age and condition.

Check the address before you negotiate

Plot, zoning, risks and land value in one file, with source and date for every value. Anything missing is marked as open.

Sources and status

Read how the reesinsy editorial team checks sources and updates these guides (in German).