Taking a Sustainable Approach to Cold Storage

Whether it’s storing cell cultures, patient samples, biologics, or other precious materials, reliable cold storage is a major requirement for many life science and pharmaceutical labs. Despite their importance, refrigeration technologies have had a tumultuous relationship with environmentalism as they are often vital but highly energy intensive. Energy consumption isn’t the only way freezers can impact the environment, however. Many older models make use of damaging refrigerants such as chlorofluorocarbons and hydrochlorofluorocarbons, which have been shown to damage the ozone layer.

As the need for more environmentally friendly laboratory practices continues to grow, many industry leaders are turning their eyes to cold storage, with the intent of developing more sustainable refrigeration technology and establishing best practices for use.

Here, we provide tips on how to take a more strategic approach to your lab’s cold storage sustainability.

Preventative maintenance

The simplest step to lower the energy cost of regular or ultralow temperature (ULT) freezers is to make use of preventative maintenance. Typically, this means regularly defrosting your freezers and keeping any filters clean, as well as more extensive maintenance concerns, such as maintaining temperature regulation and sensing hardware. Additionally, make sure all freezers in your lab undergo annual inspections to confirm the door seal and parts are in working condition. A door that can’t close properly is usually a sign of ice buildup or a poor seal and should be addressed quickly. “Cold storage units are often forgotten until they start having trouble or fail—but they are continuously drawing energy in your lab and heating up the laboratory space too,” says Christina Greever-Wilson, senior program manager at My Green Lab.  Investing in an energy monitoring device can help you to be more proactive by identifying when your cooling units are running improperly and need maintenance. 

Temperature setpoints

In many cases, the set temperature for ULT freezers is lower than what is required by regulation for what is being stored. Obviously, this will vary depending on what the freezer is housing, but there is usually no scientific reason for keeping a freezer at -80°C when preserving samples. Increasing the temperature by as little as 10°C can cut energy use by up to 30 percent. 

It is also worthwhile to double check freezer temperatures with an independent sensor. This is especially true for -20°C freezers as you neither need nor expect these to run colder than -20°C. Making sure you are accurately maintaining the desired temperature can provide long-term energy savings.

Keep inventory organized

Building an organization scheme that helps you find samples quickly and limits the time that freezer doors are open is another best practice that helps save energy. Color-coded freezer racking, using an inventory management system, and regularly clearing out unneeded or expired samples and reagents will minimize door-open time and increase lab efficiency.  Keeping the most frequently used items close to the front of the freezer is also helpful. 

Cold storage units are often forgotten until they start having trouble or fail . . .

Keeping your freezers and inventory organized can also prevent the acquisition of otherwise unneeded cold storage units. “The best way to limit plug loads from lab cold storage is to not have more units than you need,” says Greever-Wilson. “Manage the number of units you have effectively! If your number of samples has contracted significantly, power down unneeded units instead of leaving them empty. If you don’t need to store material long-term, dispose of it to make room for more important samples and reagents.”

The My Green Lab Freezer Challenge

As part of its mission to improve sustainability in scientific research, My Green Lab hosts its annual Freezer Challenge.

“The Freezer Challenge program utilizes friendly competition to enhance the sustainability of lab cold storage using well-evidenced criteria and best practices that support science quality and resilience while minimizing total costs and environmental impacts of sample storage,” says Greever-Wilson. “The original Freezer Challenge was invented by two individuals in the academic sector doing early work on laboratory sustainability at the user level—Allen Doyle of the University of California Davis and Kathryn Ramirez-Aguilar of the University of Colorado Boulder. In 2016 their idea was handed over to I2SL and My Green Lab to coordinate on a larger scale.” 

Since its conception, the Freezer Challenge has continued to grow with 2023 marking My Green Lab’s largest competition ever. Almost 2,000 labs participated, and 20.7 million kWh of energy was saved. The challenge uses a scoring system where points are awarded for completing specific best practices in freezer maintenance and sustainability. 

Shifting to a more sustainable model

If you need to invest in a new refrigerator or freezer, advocate for purchasing an energy-efficient model (the Energy Star rating in the US is an excellent indicator). To earn an Energy Star rating, freezers must meet a strict energy efficiency requirement and are at least 15 percent more efficient than the minimum standard. Acquiring a new unit should be a last resort, however, as the best option is finding ways to improve the efficiency of already owned models. 

In the end, the best method for improving the sustainability of your cold storage units is to take the time to keep them maintained and organized. By adopting regular maintenance best practices into your lab’s routine and by keeping your freezers only at the temperature needed to protect the samples stored in them, you can avoid energy waste.