ULT freezer performance and dual-temperature storage in a modern biobank: preserving sample integrity during transition

This study evaluated temperature stability, warm-up characteristics, and energy consumption of ultra-low temperature (ULT) freezers operated at-80 C,-70 C, and-60 C, to support sustainable storage practices in biobanking. Temperature and energy performance of three Haier DW-86L959W ULTs were assessed at each temperature setting with replicated measurements. Statistical analyses included Shapiro-Wilk and Wilcoxon signed-rank tests. Insights were integrated into a transitional dual-temperature storage model within a large national biobank. Temperature variation within ULTs decreased with higher set temperatures. The mean peak variation ranged from 10.1-15.1 C at-80 C to 8.8-13.0 C at-60 C. Door openings caused greater temperature increases in top-front compartments. Power failure simulations showed ULTs at-70 C had warm-up profiles similar to-80 C, differing by 2h for mean temperatures to reach-50 C, increasing to a maximum difference of 2.5h to reach mean temperatures of-20 C. However, substantial variability in warm-up times was observed among individual ULTs. Energy consumption decreased by 32% at-70 C and 47% at-60 C compared to-80 C. The dual-temperature strategy showed potential for reducing environmental impact without compromising sample safety. Operating ULTs at higher temperatures offers both operational and environmental benefits. Bio-and Genome Bank Denmark's (RBGB) dual storage strategy offers a data-driven pathway toward sustainable and scientific well-grounded biobanking. This approach ensures ongoing sample quality evaluation while supporting long-term reductions in energy consumption and carbon emissions. These findings lay the groundwork for scalable, environmentally responsible practices in biobanking infrastructures.