This paper presents a comparison between two numerical approaches for the modelling of vented hydrogen deflagrations: computation fluid dynamics (CFD) simulations and empirical engineering models (EMs). The study is a part of the project ‘Improving hydrogen safety for energy applications through pre-normative research on vented deflagrations’ (HySEA). Data from experiments conducted as part of the HySEA project are used to evaluate the CFD results and predictions from EMs. The HySEA project focusses on vented hydrogen deflagrations in containers and smaller enclosures with internal congestion representative of hydrogen applications in industry. The CFD tool FLACSHydrogen is used to simulate vented hydrogen deflagrations in 20-foot ISO containers with various obstacle configurations, and EMs for vented deflagrations are applied to the same scenarios. For the Phase 1 tests, both EM and FLACS-Hydrogen predict the maximum overpressure variation for the various configurations considered with reasonable accuracy. In general, both the EMs and the CFD tools tend to overpredict the maximum overpressures measured in the experiments. The HySEA project receives funding from the Fuel Cells and Hydrogen Joint Undertaking (FCH JU) under grant agreement No. 671461.