The drift-flux approach for predicting aerosol deposition within enclosed spaces has been refined and implemented within a commercial computational fluid dynamics (CFD) solver. The drift-flux model is tested against a previously reported study of aerosol deposition within a ventilated chamber to illustrate the performance of the approach for unsteady particle concentrations. The model has been made more general by accounting for deposition to surfaces at any angle to the gravitational vector. The algorithms for the calculation of the deposition velocity have been revised to offer improved precision. The model shows good performance when compared with the measured particle concentration decay rates. Comparison with well-mixed models shows obvious differences from the measured and drift-flux CFD approach. The dependence of point concentration measurements of decay rates on sampling time is explored and the limitations for estimating steady-state deposition behaviour are highlighted. An important aspect of aerosol ventilation of incompletely mixed enclosed spaces is illustrated. The drift-flux approach is shown to perform very well at reproducing the unsteady particle concentration decay observed. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.