Improving sustainability of ultra-low-temperature freezers at the School of Biosciences, Sheffield University

Ultra-low-temperature freezers (ULTFs) are an essential part of biological and medical research, but consume large amounts of energy. The School of Biosciences at the University of Sheffield has a fleet of approximately 80 ULTFs, which were operating at −80 °C until 2024, and contribute significantly to the School’s electricity consumption—around 1300 kW h/d in early 2024, with correspondingly high electricity costs and carbon footprint. We therefore set out to manage the use of our ULTFs more effectively, while reducing risk to research, through a combination of extensive consultation with users, improved management, and increasing the set temperature to −70 °C. We have implemented a policy of consolidating and rolling out replacements for freezers, based on energy usage rather than age. Based on a pilot programme that achieved a 62% reduction in energy, we expect to reduce energy consumption by at least 50% and simultaneously save money while also mitigating risks to research, benefiting both the School and the University. This study provides details on how these results were achieved.