Since energy and natural resource consumption are huge components of a lab’s operating expenses, no lab design today ignores “green” issues.
Higher education is a robust market for lab design, but academic labs are challenging for designers because of their high energy usage. “On average, 40 percent of all energy consumed at a university goes to research laboratories,” says Chuck McKinney, marketing VP at Aircuity (Newton, MA). For example, at the University of California, Irvine, 17 lab facilities use two-thirds of campus energy, and the University of Pennsylvania’s lab buildings consume nearly twice as much energy as their footprints would indicate. “About 60 percent of energy usage goes to heating, cooling, and moving fresh air into and out of buildings. And it’s all once-use air—no recirculation.”
WHY DO LABORATORIES CONSUME SO MUCH ENERGY?
The short answer, according to Matt Gudorf, energy manager for the University of California, Irvine, is that laboratory buildings use 100 percent outside air ventilation, with no recirculation of return air. “The entire internal air volume of a typical lab building is exhausted to the atmosphere via high-velocity exhaust stacks every six to eight minutes,” he explains. “An enormous amount of energy is required to supply, heat, cool, humidify, dehumidify, filter, distribute, and exhaust this air, and this process takes place 24/7, whether laboratories are occupied or not.” This key parameter is known as air-changes per hour (ACH). Many labs in U.S. universities, colleges, and private-sector and governmental research facilities exhaust 10 or more ACH.
Lab air requirements arise from the need to exhaust dangerous fumes, as well as the need to maintain safety and comfort given general lab activity and heat-generating equipment like freezers, pumps, and spectrometers.
Fume hood exhaust requirements are legendary, as hoods pull through many building volume-equivalents of conditioned air. Engineers have been working to improve fume hoods and their utilization for years. Low-flow designs now rule for new installations and upgrades. Other strategies involve specifying only as many hoods as are absolutely necessary and educating workers to keep sashes closed whenever possible.
Labs, McKinney says, are typically overdesigned for huge heat loads “for the worst case. And once you’ve designed for those loads, you must install ventilation systems to handle them. One problem creates an even bigger problem, particularly for labs that don’t actually experience super-high loads.”
The biggest energy hog, however, is dilution air—the minimum amount of ventilation required to mitigate operations outside of hoods. Burners, smoke, equipment that generates heat, and many fumes, while not dangerous, can make the lab environment uncomfortable. ACHs—the air volumes exchanged per hour to maintain safety and comfort—vary widely. Clean rooms use up to 30 changes per hour, while semiconductor facility values are in the hundreds. A “typical” lab uses between six and ten changes per hour.