Smart connected environments as well as digital contents are more and more present in our daily life. The former monitors various data produced by sensors, while the latter contains valuable additional information (e.g., technical data sheets, maintenance reports, employee register). When an event occurs, users generally want to figure out why this event happened. Unfortunately, most information systems in connected environments do not combine sensor network data with document corpora. Consequently, users have to look for an event explanation by querying both complementary sources with different systems, which is indeed very tedious, time consuming and requires a huge compilation effort. In this article, we apply the 5W1H model (”What? Who? Where? When? Why? How?”), commonly used in question-answering, to bridge the gap between sensor networks and document corpora. Our framework entitled ISEE (Information System for Event Explainability) offers an original approach that (i) defines events along four dimensions, (ii) interconnects semantic information coming from sensor networks and documents with 5W1H connections, and (iii) provides to the user a set of preliminary event explanation according to 5W1H answers. A real motivating use-case based on a smart-building is presented and experimental results are discussed.