Laboratory Hood Energy Savings: The Low-Hanging Fruit

Abstract

Laboratory safety and energy savings are currently occupying the same space in many engineering conversations regarding lab design and construction. Exhaust from lab hoods is particularly prominent in such conversations. There are a wide variety of strategies that can be applied to save energy by reducing hood exhaust, from the inexpensive approach of lowering face velocities to the more expensive variable air volume (VAV) lab hood exhaust systems. Whatever energy-saving strategy is chosen, it should maintain good hood containment. Once this central truth is accepted, energy savings with established containment becomes straightforward to measure. Overall energy-savings techniques can be subdivided into separate components and analyzed for effectiveness. Low-exhaust technologies are not additively cumulative, but multiplicative in nature. Each strategy can reduce total energy use by a percent of the whole; the next strategy has a lower “whole” from which to produce savings and so forth. Since each savings strategy has an up-front cost, it only makes sense to use the least expensive strategies first, followed by the costlier strategies. Using this approach, smaller lab hoods, lower face velocities, lower operating sash openings, and nonoccupied hood exhaust setbacks produced much more significant and less expensive savings than more expensive approaches like heat reclamation and VAV. Of course, like any generalized strategy, there are some important qualifications that may shift more expensive strategies to a higher priority.