The use of feedback in lab energy conservation: fume hoods at MIT

The purpose of this paper is to report on the results of an Massachusetts Institute of Technology Chemistry Department campaign to reduce energy consumption in chemical fume hoods. Hood use feedback to lab users is a crucial component of this campaign.

Sash position sensor data on variable air volume fume hoods are remotely collected. A 15 minutes average fume hood sash positions for each laboratory are recorded. Data are compiled monthly and a report with average sash position over time and relative frequency of hood position are delivered to the principal investigators of the labs.

Average sash height is lowered by 26 percent (from 16.3±0.85 percent open to 12.1±0.39 percent open) throughout the department, saving an estimated $41,000/year. Sash position during inactive periods is lowered from 9 to 6 percent open. Half of all department savings occurred in four (of 25) labs. Energy savings are substantially less than original expectations because most installed fume hoods use combination sashes. Labs with vertical sashes use the most energy, and see the most savings from the intervention.

Monthly feedback is an effective tool for encouraging better hood use behavior. Potential savings from even large behavior changes can be limited if existing equipment is relatively efficient, so conservation programs should be tailored to the existing conditions.

The present analysis provides data on the impact of a program in a relatively efficient setting compared to other fume hood conservation reports. The results have cautionary value for designers of similar programs. A breakdown of a laboratory building utility use is also provided.