With the entry into force of the Regulation "EnEV" in 2007, the EU Directive (European Performance of Buildings Directive) adopted in 2002 on the overall energy efficiency of buildings was incorporated into the german national law. Paragraph 16 of the "EnEV" stipulates that the owner, potential buyer or tenant of a property must be presented with a statement of the energy performance of the building when constructing, purchasing or renting it. The introduction of the energy certificate is intended to raise general awareness of the energy quality of buildings and thus increase the demand for energy-efficient buildings. In addition, the legislator demands concrete proposals for the cost-effective improvement of the overall efficiency, which must be attached to the energy performance certificate as so-called modernisation recommendations. For this purpose, a catalogue was developed with basic modernisation recommendations for improving the energetic quality of the building envelope, taking into account aspects of building construction, building physics and design, and renovation measures were examined with regard to costs and economic efficiency. Furthermore, the building component connections play a central role in the entire planning and construction process of a modernization measure. The redevelopment solution for the area is often not the problem. The difficulty often lies in the constructionally and building physics-based flawless detail training. In cases in which it is difficult to precisely define the existing structure due to the vast number of different constructions, basic solution approaches are formulated which can be used as a basic decision-making aid.