This paper reports on an experimental and analytical investigation on the potential displacement effect of a diffuse ceiling ventilation system. Experimental data was generated in a test chamber where measurements of four test series were conducted for two different placements of the exhaust. Furthermore, CFD calculations were performed to support the analysis of the experimental results. The results show that tendencies known from conventional displacement ventilation occur at low heat loads and a development towards full mixing with increasing heat load. It has been demonstrated that the vertical air velocity profiles, temperature distribution and ventilation effectiveness are independent of the Archimedes number. (C) 2014 Elsevier B.V. All rights reserved.