Raising poultry in livestock buildings requires housing that can provide acceptable living conditions in terms of climate and air quality. Accurately assessing the interior climate dynamics of a naturally ventilated poultry house needs advanced computer-based modelling tools. The present work proposes a three-dimensional modelling tool that uses computational fluid dynamics (CFD). External and internal climate and the sensible and latent heat emitted by the hens were included in the model in accordance with the principles that govern heat and mass transport, momentum, and radiative energy. Experimental data were used in the proposed 3D CFD model to predict the internal climate, considering a time series when wind blew perpendicular to the ridgeline. A period of 3h30min, occurring under a stable wind direction was replicated, resulting in an overall RMSE of 1 °C and 1 g [H 2 O] kg −1 [dry air] for temperature and absolute humidity, respectively. In addition, the coefficient of variation indicated that the experimental data pertaining to the internal climate showed less overall variability than did predicted data. Subsequently, the 3D CFD model generated predictions concerning to air discharges emitted horizontally through side vents, and caused by natural ventilation. Air discharge predictions defined regions close to the poultry house by means of assessing air quality. Also, air discharge predictions were then used to adapt the governing equations of the PRIME-AERMOD model to replicate in a simplified approach air discharge from a naturally ventilated poultry house.