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Improving Energy Efficiency in Cold Storage Systems

Better refrigerants and best practices improve energy efficiency

Mike May, PhD

Mike May is a freelance writer and editor living in Texas.

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The best opportunity to reduce your lab’s overhead might be hiding in a corner. It’s your cold storage. If you have an ultralow-temperature freezer, it uses about as much electricity as an average household, according to Karen Wisniewski, commercial director for cold storage at Thermo Fisher Scientific (Waltham, MA). “Moving from a conventional ultralow-temperature freezer to a more efficient one can save as much as $1,500 a year,” she says. With a decadelong or longer lifetime, that saves significant money.

The improvements in energy-efficient technology come largely from three advances: better insulation, variable-speed recirculation, and using hydrofluorocarbon (HFC) refrigerants. “Vacuum-insulated panels allow thinner walls and more efficient use of space,” Wisniewski says. “You can store more samples in a freezer, so you don’t need as many [freezers].”

Various economic factors also drive the use of more energy-efficient cold storage. “Some institutions offer rebates as an incentive for labs to purchase energyefficient freezers,” says Gary A. Bissig, vice president, central region, at LABRepCo (Horsham, PA). “Some for-profit businesses even mandate that new freezers [be] energy-efficient.”

At the University of Colorado, Boulder, for instance, labs receive “financial incentives toward the cost of lab equipment—including refrigerators and freezers— based on energy savings if scientists choose to purchase energy-efficient units,” says Kathryn A. Ramirez-Aguilar, green labs program manager.

Easy improvements

The way that a lab uses a freezer also makes a difference. “Every time you open the door, you put stress on the unit,” Bissig says, “so you should get in and out as quickly as possible.”

For another thing, where you put cold storage determines how efficiently it will work. “Freezers need space around them to breathe so that they can dissipate some of the heat,” Wisniewski explains, “and don’t put them in front of a south-facing window.”

Once you pick a good spot for your freezers, keep them defrosted. “In some labs, you open a freezer and find that it’s full of ice,” says Wisniewski, “and that makes it work harder.”

Even the electricity coming to a freezer impacts its efficiency. “Make sure to have a steady line voltage,” Bissig says.

At the University of Colorado, Boulder, Ramirez-Aguilar encourages even more ways that users can save energy in cold storage. “Energy efficiency for cold-sample storage is a subject of significant importance at the university.” As an example, she points out that about half of the university’s ultralow-temperature freezers, which are typically kept at minus-80 degrees Celsius, are now kept at minus-70 to save energy. That, Ramirez-Aguilar says, can typically save two or four kilowatt hours per day per freezer.

In addition, she points out that energy efficiency can be considered in all lab cold-storage devices, from minus-20 and 4 degrees Celsius storage through ultralow temperatures. Her team is “encouraging consolidation, retirement of unneeded units, sharing, and using freezer space effectively and efficiently.” To reach those goals, she says that labs can “inventory and clean out samples no longer needed [in order] to minimize the purchase of freezers.” She says that her facility “has mobile minus-20 degrees Celsius freezers that labs can borrow while defrosting and cleaning out freezers.”

Ultimately, labs use freezers to preserve and protect samples. As Wisniewski says, “You cannot sacrifice samples in the freezer to save energy.” So sample protection comes first, and it is growing increasingly important to ensure that protection is provided in the most environmentally sound and energy-efficient manner. Getting the most efficiency and the best sample protection depends on a combination of technology and best practices. The first of those costs some money, but it’s returned quickly, and the second often just takes thinking a little about how and where you use cold storage.

For additional resources on cold storage, including useful articles and a list of manufacturers, visit