A semantic sensing system includes a semantic engine coupled to one or more sensing entities, and a memory having a plurality of semantics and semantic inference rules. A semantic engine is configured to interpret the plurality of rules to determine a composite semantic by inferring a first semantic, determining a second sematic based on an external input, and infer a composite sematic based on the first and second semantics and a semantic inference rule. A plurality of access control rules associate a time interval and a semantic, and the semantic engine identifies a first access control rule from among a plurality of access control rules to perform an access control action.