In energy certification schemes for existing buildings, barriers have been reported regarding quality, communication aspects, certification of apartment buildings and lack of expert (auditor) capacity. In order to contribute to tackling these barriers, the European project IMPACT has the objective to test energy performance certification for existing buildings from 6 pilot countries, to exchange experiences and success factors, derive recommendations for improvement of tools, certification schemes, training of experts, communication, to support the EPBD implementation process in 6 countries, to disseminate project results on a national and EU wide scale. This report gives guidelines from the ImPACT Project.