There have been numerous articles on energy conservation schemes in buildings with a large number of fume hoods. These articles often have dealt with various variable-air-volume schemes to control individual laboratory environments. However, they generally do not provide an overall comparison among these schemes and the control devices involved in implementing these schemes.

Two basic methods of fume hood variable-air-volume exhaust are described in this paper. Field experience addresses basic differences between the two methods. A testing facility was recently constructed and used to test performance characteristics of six commercially available fume hood exhaust control devices. Some specific differences were observed, but the devices generally per,. formed the basic function of maintaining constant face velocity.