Context modeling has attracted increasing attention due to the prevalence of context-aware applications within smart environments. Whilst upper-level context ontologies exist for use within smart environments, none offer a single generalized model covering all high-level elements that exist across all types of smart environments. This paper presents an upper-level context ontology for smart environments which aims to incorporate all factors deemed important for context in smart environments. Specifically, the proposed model considers key factors that include User, Object, Location, Application, Event, Natural Element and Temporal. The model is able to represent daily routines encompassing both open-world and closed-world activities and this is presented in a short vignette.