One salient feature of data produced by the IoT is its heterogeneity. Despite this heterogeneity, future IoT applications including Smart Home, Smart City, Smart Energy services, will require that all data be easily compared, correlated and merged and that interpretation of this resulting aggregate into higher level context, which better matches people needs and requirements, bringing the user experience to the next level. In this paper we propose a framework based on semantic technologies to aggregate IoT data. Our approach has been assessed in the domain of the Smart Home with real data provided by Orange Homelive solution. We show that our approach enables simple reasoning mechanisms to be conducted on the aggregated data so that contexts such as the presence, activities of people as well as abnormal situations requiring corrective actions, be inferred.