Two criticisms are often associated with energy system models. First, many models are so complex that they are not reproducible outside the developer’s group. Just the parametrization of the model requires days and special knowledge. Second, many models cannot be validated by external users, since core data is missing or is internal. The solution may be a combination of transparency through FAIR data and the transition from closed model building to open-source. This presentation demonstrates - the process of switching from closed to open source for the agent-based model AMIRIS, - the FAIRification of its data by linking it to the Open Energy Ontology and the enrichment with metadata, and - community building as well as the publication in open journals like JOSS.