Renewable energy concepts for buildings and districts are increasingly demanded in order to meet both international climate goals and national legal requirements. In this context, we developed comprehensive concepts for different buildings and districts in practice, making extensive use of detailed building simulations for a reliable prediction of energy demands. Main goal was to achieve a reasonable compromise between independency from fossil price fluctuations and economic efficiency. In this paper, we present the according planning process and the concepts, which are currently being realised or in further planning phases.