A wind tunnel metabolism chamber is described which has a low (4.2 to 1) ratio of total to working volume to facilitate respiratory gas exchange measurements on unrestrained animals. Fine mesh screens smooth air flow to obtain 2% RMS turbulence and +or-5% uniformity. Simultaneous combinations of air temperature from -10 to 50 degrees C and wind from 0 to 3.6 m s^-1 can be maintained indefinitely. A window admits simulated solar radiation to the working section.