Correlative engineering models (Linden 1994), are compared to recent published (Cariteau et al. (2009), Pitts et al. (2009), Barley and Gawlick (2009), Swain et al. (1999), Merilo et al. (2010)) and unpublished (CEA experiments in a 1 m3 with two openings) experimental hydrogen or helium distribution in enclosures (with one and two openings). The modelling-experiments comparison is carried out in transient and in steady state conditions. On this basis, recommendations and limits of use of these models are proposed.