The lay-out requirements developed for hydrogen systems operated in industrial environment are not suitable for the operating conditions specific to hydrogen refuelling stations (service pressure of up to 95 MPa, facility for public use). A risk informed rationale has been developed to define and substantiate separation distance requirements in ISO 20100 Gaseous hydrogen ? refuelling stations [1]. In this approach, priority is given to preventing escalation of small incidents into majors ones, with a focus on critical exposures such as places of occupancy (fuelling station retail shop), while optimizing use of the available space from a risk perspective, a key objective for being able to retrofit hydrogen refuelling in existing stations.