In order to reduce the energy gap originated by the difference between existing tools estimations and real energy consumption, HIT2GAP European H2020 project aims at advancing on building control tools by providing a newer decision-making technology. Technically, HIT2GAP o ers a platform inspired by previous reference architectures (e.g., Haystack) and complements them through a knowledge-based model, called OntoH2G, to store building information under a common vocabulary and consequently to enable ne-grained vision of the building with its equipment and occupants. OntoH2G allows to query building data so to extract required information and interesting events (through a set of services). OntoH2G advances over existing models on two main aspects: (i) being compliant with well-known ontologies in di erent domains in order to cover all energy building concepts, and (ii) its ability to represent user/occupant behaviour, preferences, and interactions.