Energy efficient buildings require high quality standards for all their technical equipment to enable their efficient and successful operation and management. Building simulations enable engineers to design integrated HVAC systems with complex building automation systems to control all their technical functions. Numerous studies show that especially these supposedly innovative buildings often do not reach their energy efficiency targets when in operation. Key reasons for the suboptimal performance are imprecise functional descriptions and a lack of commissioning and monitoring of the technical systems that leave suboptimal operation undetected. In the research project "Energy Navigator" we create a web-based platform that enables engineers to create a comprehensive and precise functional description for the buildings services. The system reuses this functional description - written in an appropriate domain specific language - to control the building operation, to signal malfunctions or faults, and in particular to measure energy efficiency over time. The innovative approach of the platform is the combination of design and control within one artifact linking the phases of design and operation and improving the cost effectiveness for both services. The paper will describe the concept of the platform, the technical innovation and first application examples of the research project.