The focus of the research project ìlife cycle improvement of the building qualityî is to develop, analyze and evaluate methods to assess planning decisions about their consequences on the life time of a building. The calculation of investment costs often serves as the only basis for decision-making in the building planning. The existing set of approaches for assessment is used only in a limited number of decision processes. The purpose of a certain building does not only lie in cost efficiency or in environmental compatibilityóits main purpose needs to be focused on usability. This inevitably is connected to the planned and accomplished quality. The project has two main outputs. One is the creation of a common database on building life cycle data; the other is a comprehensive guideline on sustainable building. The comprehensive guideline will be structured on the life cycle of a building and contain defined time slots, where decisions are necessary and what information will be helpful for a decision maker. The focus of the common database will lie on data, which have to be estimated during the planning of a building. These are LCC- and LCA- Data. As both of these Analyses need a calculation of the energy demand, the data are to be accomplished with the data from the energy performance certification. The comprehensive guideline and the data base will be placed in an internet portal, which shall give pubic and quick access to the scientific data. As this Internet portal is still in programming and the collection of scientific data is continuously but will also take some time to be useable, a quick prototype within excel is created to show our goal. It is an enhanced energy certificate.