The energy performance certificate provides data on the energy efficiency and energy costs of a building. Energy performance certificates have been mandatory for all residential buildings in Germany since 2009. Since 2014, landlords/-ladies are required to include information on the energy efficiency standard in the property advertisement. In the apartment listing on Wunderflats, the landlord/-lady can provide information on the energy performance certificate. In the case that the license has only just been requested or is not needed for the building, this can also be indicated in the listing.