Several CFD (computational fluid dynamics) simulations of the three-dimensional airflow with heat and mass transfer in a complex geometry indoor swimming pool were performed using the OpenFOAM software. A solver has been developed to take into account the mass transfer and the appropriate thermal boundary conditions. Several turbulence models RANS (Reynolds-Averaged Navier-Stokes) types were used. The comparison of numerical results with experimental measurements of air velocity, temperature and humidity showed good agreement regardless of the turbulence model. In order to evaluate the weather effect on the indoor atmosphere of the swimming pool, two simulations were carried out with winter and summer weather conditions. Their comparison showed a very small effect on the internal environment which is manifested by a greater temperature stratification in winter. Furthermore, the effect of swimmers on the indoor atmosphere of the swimming pool was evaluated and found to be of great importance. The main advantageous effect is the homogenization of the temperature and the specific humidity in the occupied space. On the other hand, its major adverse effect is the increase of the specific humidity in the air. (C) 2017 Elsevier Ltd. All rights reserved.