Accurate Energy Efficiency Optimization: Semergy involves elaborate calculations to determine the heating (energy) demands and other optimization key figures. These calculations depend on multiple factors including (among others) the building geometry, building type, construction selection and building products. Since doing these calculations manually is a complex task, a Semergy user can benefit from the automated calculation and its accurate results. Interactive Decision Support: Since there is a multitude of potential building refurbishment measure combinations, Semergy includes an optimization and decision support methodology that supports the user in finding the optimal choice based on the user’s requirements, as well as economic and ecologic parameters, while still respecting the physical structure of the existing building. Extensive Knowledge Repository: A Semergy user can benefit from the extensive data repository used by Semergy including different building constructions (walls, roofs, windows, etc.) as well as a multitude of suitable building products organized into classes (insulation materials, etc.). Each entry is supplemented with specific physical, environmental and economic properties for its evaluation during the optimization run. Comprehensive Reporting: Since the finally selected optimization solution’s properties might be difficult to remember in detail, Semergy provides the user with the option of creating a detailed written report than contains all details of the proposed optimization solution, including the status quo building properties, the refurbishment measure details and the expected improvements in energy efficiency.