Treats measurements of ventilation rates in a model building and wind tunnel. 2 types of opening, circular holes and model windows were tested under 2 wind cOnditions. one wind condition was selected to give maximum flow through the model; with theother, ventilation was mainly due to turbulent pressure fluctuations. Illustrates different characteristics of theopenings. Draws comparisons between measurements and theoretical predictions. Discusses use of wind tunnels for ventilation studies. NOTES: A further comment on this paper was published in Building and Environment vol.15 no.141.