The project SESAME uses semantic technology in creating a technical solution that integrates smart metering and demand management, and building automation. Employing policy-based reasoning, it offers an energy-optimization capability both for the energy consumer and provider. The information used is coming from sensors of multiple domains, including the physical sensors (such as temperature, light, presence) and the information sensors from the energy management domain services, as well as the structured data from user profiles, policies, and external information sources. The SESAME approach is implemented and validated as an extensible smart home demonstrator system which provides a proof-of-concept for its innovative energy efficiency solution.