When you think about saving the planet, you probably don’t imagine cracking open a freezer in a lab. Yet that’s exactly where a quiet revolution in sustainable science is happening.

In the Reinhardt Laboratory at McGill University, researchers have dialed up the temperature of their ultra low temperature freezer. Instead of the traditional minus 80 degrees Celsius, they’re now running at minus 65. And the science hasn’t melted away.

Why colder isn’t always better

For decades, biomedical labs have treated -80 °C as gospel. The so-called “-80 freezers” became standard not because evidence demanded it, but because that’s how things had always been done. Colder is always better, the sentiment goes. These massive machines are the vaults of modern biology, crammed with tissues, enzymes, antibodies, and samples that might someday unlock cures.

But as Dieter Reinhardt, PhD, Canada Research Chair in Cell-Matrix Biology, explained, that frigid number is more tradition than necessity. “Compressors have to work very hard to maintain these ultra-low temperatures,” Reinhardt said in a statement. “This requires a lot of electricity, but it’s also hard on the compressors and will shorten the lifespan of your equipment, which is expensive to repair and replace. Increasing the temperature by just a few degrees can add years to this equipment and decrease how often you have to defrost it.”

By inching up the temperature, labs can cut electricity use by as much as 30 percent. That matters because McGill alone has hundreds of these freezers running around the clock. Collectively, there are tens of thousands of such freezers across the world. The potential savings—both financial and environmental—are enormous.

The science of not-so-cold

Still, you can’t just toss every biological sample into a warmer freezer and hope for the best. Some reagents are sturdy enough at -65 °C. Others, like messenger RNA, are notoriously fragile. Reinhardt admitted the tradeoff: “Experience has taught me that for my reagents, there’s not too much difference between -80 C and -65 C, which is what we’re using now. But if you’re storing lots of messenger RNA, for example, your freezer might need to be colder because these reagents are the most sensitive to degradation.”

That’s why researchers worldwide are sharing data on what survives at different temperatures. Independent consultant Allen Doyle launched the “Just Call Me Ultra-Low” campaign to break the cultural association between freezers and one magic number. The goal is to build evidence—sample by sample—that scientists can still maintain their samples while being less wasteful.

This isn’t McGill’s first experiment with greener storage. Back in 2011, the Faculty of Medicine got support from the Sustainability Projects Fund to store DNA samples at room temperature. It worked, proving that in some cases the freezer wasn’t needed at all.

And there’s another problem: most of what’s inside these machines never actually gets used. “The reality is probably 80 to 90 per cent of the typical items stored in an ultra-low freezer are not being actively used and may never be,” Reinhardt said. Those precious leftovers accumulate because it takes years to generate them. Rather than trashing old samples, labs squirrel them away. That means freezers become cluttered, energy-hungry graveyards. Reinhardt’s solution: keep accurate inventories and clean house regularly.

The movement is now going global, with the International Freezer Challenge encouraging labs to rethink storage practices. Since its launch six years ago, it has saved more than 24 million kilowatt hours of energy worldwide. McGill has joined in, offering its own prizes to participating labs.