This paper details an experimental and analytical investigation of flow in an enclosure containing a cold plate located on a wall above a hot plate. The colliding boundary layer flow that results and consequent thermal stratification in the enclosure has been modelled first using a water-filled scale model. The full scale situation corresponds to a room with a cold window surface above a heater panel on one wall. A flow element model has been developed using standard boundary layer and plume flow relations to model the component flows in the enclosure. The model provides a good estimate of mean temperature in the enclosure and a conservative prediction of the stratification between the top and bottom.