Building construction has gone through a significant change with the emerging spread of ICT during last decades. Intelligent buildings are equipped with building automation systems (BAS) that can be remotely controlled and programmed. However, such systems lack convenient tools for data inspection, making building performance and efficiency analysis demanding on large sites. The paper presents an adaptation of Semantic Sensor Network ontology for use in the field of building operation analysis. The proposed Semantic BMS ontology enriches the SSN with a model of building automation data points and describes relations between BAS and physical properties of a building. Proposed ontology allows facility managers to conveniently query BAS systems, providing decision support for tactical and strategic level planning.