A building management system comprising: a building system interface configured to access a building system; an event service module configured to access event data in the building system through the building system interface; a knowledge base providing a model of the building system, the model including semantic descriptions of the event data, the semantic descriptions of the event data being arranged in an ontology; a semantic service module in communication with the knowledge base; and a user interface in communication with the semantic service module and the event service module, the user interface configured to generate a user request to create an event filter having a filter criterion and report event data matching the filter criterion; characterised in that for creating the event filter the building management system is configured to: issue, to the semantic service module by the user interface, the user request to create an event filter; the semantic service module configured to access the knowledge base to retrieve event data entries matching the user request; the knowledge base configured to provide metadata from event data entries matching the user filter criterion to the user interface; the user interface configured to send a request to create an event filter to the event service module based on the metadata retrieved from the knowledge base, which encode the filter criterion; and the event service module configured to create the event filter and to send an acknowledgement to the user interface that the event filter has been created. a building system interface configured to access a building system; an event service module configured to access event data in the building system through the building system interface; a knowledge base providing a model of the building system, the model including semantic descriptions of the event data, the semantic descriptions of the event data being arranged in an ontology; a semantic service module in communication with the knowledge base; and a user interface in communication with the semantic service module and the event service module, the user interface configured to generate a user request to create an event filter having a filter criterion and report event data matching the filter criterion; characterised in that for creating the event filter the building management system is configured to: issue, to the semantic service module by the user interface, the user request to create an event filter; the semantic service module configured to access the knowledge base to retrieve event data entries matching the user request; the knowledge base configured to provide metadata from event data entries matching the user filter criterion to the user interface; the user interface configured to send a request to create an event filter to the event service module based on the metadata retrieved from the knowledge base, which encode the filter criterion; and the event service module configured to create the event filter and to send an acknowledgement to the user interface that the event filter has been created. issue, to the semantic service module by the user interface, the user request to create an event filter; the semantic service module configured to access the knowledge base to retrieve event data entries matching the user request; the knowledge base configured to provide metadata from event data entries matching the user filter criterion to the user interface; the user interface configured to send a request to create an event filter to the event service module based on the metadata retrieved from the knowledge base, which encode the filter criterion; and the event service module configured to create the event filter and to send an acknowledgement to the user interface that the event filter has been created.