A Matter of Degree

Not many nightmare scenarios grip Kristala Jones Prather’s imagination. But one that haunted her for a long time involved the −80 °C freezer in her Massachusetts Institute of Technology lab. Freezer temperatures can vary by a degree or two, especially when researchers constantly open and close doors to pull out or store precious samples. But what if the freezer warmed up over a long weekend because of a mechanical failure or power outage? Prather and her team need ultralow temperatures to stash microbes they have engineered to make biofuels and other valuable chemicals. A warmed, suboptimal freezer might ruin work, thwart grant proposals, and delay thesis defenses. Little wonder that the idea of the Prather lab’s freezer temperature hitting −70 °C felt, she says, “like the end of times was coming.” Until Prather had what she calls her revelation. Her lab became a pilot case for MIT’s Green Labs Program in April 2016. During the certification process, she learned that setting the freezer to −80 °C was overkill for her lab’s cultures and a waste of energy besides. “We call them minus-80 freezers, but you can set them to whatever you want,” she says. She chuckles at the thought that since summer 2016, her freezer has been set to −70 °C, the very temperature that used to trigger panic. Greening a laboratoryapplying sustainable strategies to reduce a lab’s impact on the environmentisn’t a new concept. But the tale of the low-temperature freezer illustrates a challenge in this field. Some not-so-sustainable practices are culturally driven rather than based on necessity. And the activation barrier to behavior change can be intimidating, even for an intervention as straightforward as adjusting a touch pad or dial. The go-to ultralow-temperature freezer setting was not always −80 °C, says Allen Doyle, an independent consultant and longtime sustainability manager who’s worked at the University of California’s Santa Barbara and Davis campuses. He’s encountered more senior scientists who call ultralow-temperature freezers “the minus 70” instead of “the minus 80.” Doyle and other sustainability managers who spoke with C&EN suspect marketing campaigns got the concept of −80 °C stuck in researchers’ heads. As freezer technology improved, companies offered ever-colder operating temperatures. Scientists simply came to believe that colder was better for every sample, whether or not that was the ads’ intent. “I call the trend ‘cold creep,’ or ‘freezer wars,’ ” Doyle says. It would take scientific curiosity to reverse it. Kathryn Ramirez-Aguilar hadn’t been this excited about a phone call in some time. It was early 2010, and a researcher had phoned her to relate how she was squeezing more life from a struggling −80 °C freezer. Ramirez-Aguilar, an analytical chemist by training, was relatively new to her job as Green Labs Program Manager for the University of Colorado, Boulder. As Ramirez-Aguilar recalls, the lab had called a freezer technician, who, after some tinkering, suggested going easy on the machine by adjusting the temperature to −70 °C. That sounded risky to the researcher. Uncertain, she contacted the lab’s principal investigator to ask permission for the change. To everyone’s surprise, the group leader had no problem with increasing the temperature and even mused, like Doyle’s senior scientists, that he