The paper presents an extensive experimental and numerical study on a cross-ventilated building providing important features of the induced flow patterns at the two openings as a function of the free stream wind velocity's magnitude and its incidence angle. The experimental data are measured via anemometers across the openings, whilst the numerical methodology is based on the time-dependant solution of the governing Navier-Stokes equations. The experimental data are compared to the corresponding numerical results, revealing the unsteady character of the flow field especially at large incidence angles. Furthermore, additional information regarding the flow field near the opening edges, not easily extracted by experimental methods, provide an in depth sight in the main characteristics of the flow field both at the openings but also inside the building. Finally, a new methodology for the approximation of the volume flow rate aerating the building based on experimental measurements of the velocity field at the openings is presented. (C) 2011 Elsevier B.V. All rights reserved.