In the frame of a multi-year EU project, the set of European Standards from 2006/7 to support the European Energy Performance of Buildings Directive (EPBD) is undergoing a revision. The majority of the standards describe calculation methods. Based on the experience with the first generation of the standards and on a EU research project investigating the application of the standards in the Member States, a rigorous set of requirements has been set up. This includes issues like unambiguity and software proofness. The new standards have been developed in a modular structure and supported by accompanying technical reports and spreadsheets.