A person in Germany who sells or rents out a house or an apartment must show an Energieausweis, an energy certificate, to the interested party. This must happen at the latest during the viewing. The certificate states how much energy the building needs or uses, and it gives an efficiency class. If a certificate exists, the real estate ad must already list key figures from it. These include the energy demand or consumption, the main source of heating energy, the year of construction and the efficiency class. After the contract is signed, the buyer or tenant receives the certificate or a copy. An owner who does not show it in time can be fined up to 10,000 euros.