Measured and calculated properties relevant to the flow in ventilated rooms are reported. The measurements were obtained by laser-Doppler anemometry in a small-scale model room with a single square inlet. The calculations made use of a numerical procedure which solves, in finite-difference form, the elliptic partial-differential equations for three components of velocity, the pressure, the turbulence energy and its dissipation rate. Calculated results are shown to be in close agreement with the present measurements and with other available experimental data. With this justification, the procedure is used to quantify the dependence of the velocity characteristics of different geometric arrangements. The results provide guide lines for the design of ventilation systems.