Multizone building energy simulation (BES) programs become popular among building designers. They include a wide variety of techniques and advanced heat transfer models,yet require only limited computational time. Unfortunately, the use of correlations to predict the convective heat transfer undermines their reliability. The available correlations actually apply only to specific cases. For example, they are only valid for one diffuser type at a particular location. Yet, convective heat transfer modelling is particularly important in mixed convection regimes with high ventilation rates, such as night cooling. So it is self-evident that researchers would investigate to what extent including more room/system design parameters is necessary to model mixed convection heat transfer. The authors of this study imitated sequences of typical mixed convection cooling regimes (a day regime possibly preceded by night cooling) in a modified PASLINK cell and varied the air supply/exhaust configuration and added to some cases a thermally massive floor. The analysis is based on airflow data and the convective heat flux. The results indicate that the supply/exhaust configuration is particularly important when high ventilative flow rates are combined with (heterogeneously distributed) thermal mass. Unfortunately, existing convection correlations cannot predict the convective heat flux accurately for the studied cases. (C) 2012 Elsevier B.V. All rights reserved.