Virtual Reality (VR) can help designers to realise later life phase situations of a product in presence of a specific actor (or actors) in a specific environment by building product use-cases in VR, thus facilitating an early evaluation of a design. In this paper, we present a model-based approach that uses SysML behaviour models to describe and control VR environments. The behaviour modelling process with SysML and the simulation results obtained using these behaviour models are discussed. An overview over simulation processes is provided by constructing an example product use-case in VR.