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.

Methods

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.

Results

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 2 h for mean temperatures to reach −50 °C, increasing to a maximum difference of 2.5 h 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.

Conclusions

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.

Keywords: biobanking; storage temperature; sustainability; ultra-low temperature freezers

Madsen, Corrie L. and Høgdall, Estrid. „ULT freezer performance and dual-temperature storage in a modern biobank: preserving sample integrity during transition“ Journal of Laboratory Medicine, vol. 50, no. 1, 2026, pp. 10-20. https://doi.org/10.1515/labmed-2025-0108