Two-dimensional isothermal airflows in a ventilated room were numerically investigated by applying different turbulence models that range from zero- equation model to Reynolds Stress Transport models. Quantitative and qualitative comparisons were made between the numerical results and corresponding experimental data from Particle Image Velocimetry (PIV) and Hot-Wire Velocimetry (HWV). Comparisons showed that the airflow patterns predicted by zero, one-equation and k-ε models were similar to those observed in hotwire measurement while airflow patterns predicted by RSM, k-ω and k-ω-SST were similar to PIV measurements. Mean velocities predicted by all models agreed better with experimental data in the left part than in the right part of the room. But in the right part of room, there also existed big differences between the mean velocities from PIV and those from HWV. As to turbulent kinetic energy, predictions of RSM, k-ω and k-ω-SST models were more close to HWV measurements than all the k-ε models tested. However, discrepancy between predictions and measurements still existed especially in the right part of the room. The differences between predictions and measurements were discussed and possible reasons were pointed out: low Reynolds number effects could have caused the differences.