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 have been required to include information on the energy efficiency standard in the property listing. On Wunderflats, landlords can add information on the energy performance certificate. They can also indicate if the license has been newly requested and isn't yet available or if it isn't required for the building.