Natural ventilation can be used to improve indoor air quality, remove contaminants from spaces and to remove heat from a building during the day, or during the night. In some cases, openings for natural ventilation are equipped with shading devices – such as louvers – to reduce solar heat gains while allowing natural ventilation. This study presents wind-tunnel experiments and computational fluid dynamics (CFD) simulations of a cross-ventilated building equipped with louvers. Four opening positions are studied: (i) openings in the center, (ii) upper or (iii) lower part of the windward and leeward facades or (iv) one opening in the upper part of the windward facade and one opening in the lower part of the leeward facade. The 3D steady Reynolds-averaged Navier-Stokes (RANS) simulations are performed with three turbulence models (RNG k-ε, SST k-ω, RSM) and validated with the wind-tunnel experiments. The experimental results show that the largest velocities occur in a building with openings in the upper part of the facade. The best agreement with experimental data is provided by RSM. In addition, CFD simulations for buildings without louvers are conducted for the same opening positions to evaluate the effect of louvers on the dimensionless volume flow rate, age of air and air exchange efficiency. The highest dimensionless volume flow rate at reduced scale (0.69) is obtained in the building with louvered openings in the upper part of the facade and the highest air exchange efficiency is achieved for a building with louvered openings in the center of the facade (45%).