A Fickian model is used to simulate the wine losses during wine ageing in oak casks. The model relates wine losses due to diffusion through oak staves and evaporation to the air depending on conditions of temperature, relative humidity and air velocity in ageing facilities. The governing parameters are diffusion and surface emission coefficients. Both are fitted to experimental data. The model is validated by comparing it with experimental data from several case studies in wine-cellars. The results obtained are in close agreement with actual measurements. The model is a useful tool for optimising the design of air diffusion systems to minimise wine losses and, consequently, financial losses for cellar owners.