The energy certificate provides data on the energy efficiency and energy costs of a building. This is to allow people to compare between properties and to assist tenants or prospective buyers with their rental or purchasing decision. Energy certificates have been mandatory for all residential buildings since 2009. Since the amendment of the Energy Saving Ordinance (EnEV), which has been in force since 1 May 2014, sellers or landlords have to state the energy efficiency standard already in their real estate advertisements. When renting or selling, prospective tenants or buyers have the right to see the energy certificate and can ask the owner, landlord, or seller, for example during an apartment viewing. Anyone who deliberately or carelessly fails to hand over such a certificate, as well as failing to provide a complete certificate and on time, will face a fine of up to € 15,000.