50% of CU Boulder ULT freezers at -70 ⁰C

Half of the ultra low temperature (ULT) freezers on the CU Boulder campus are at -70 ⁰C (~75 of ~150 freezers). In 2010, there were probably only 5 at -70 ⁰C.  The CU Green Labs Program is very proud of this, and we hope to continue to encourage laboratories to switch their freezers to -70 ⁰C where it makes sense for their samples. One item that has encouraged this progress is the fact that we had a number of campus scientists that were already setting their ULT freezers to -70 ⁰C and had been for a very long time, before CU Green Labs even started. Knowing that colleagues had been successful storing samples at that temperature probably helped to convince some labs to change. Check out the labs and departments taking conservation actions with their ULT freezers!

What are benefits of raising your ULT freezer temp from -80 ⁰C to -70 ⁰C?Give your freezer compressor a break by raising the temperature poster

  • Extend the life of your ULT freezer! Increasing the temperature of your freezer means the compressor does not have to work as hard. Since the compressor is working less, there is reduced risk for compressor failure.
  • Energy savings! Based on metering data from ULT freezers at two temperatures, it is easy to see the energy saving impact of raising your unit’s temperature to -70 ⁰C.
    • 21.8 kWh/day (at -83 ⁰C) to 14.6 kWh/day (at -70 ⁰C) on a very old upright Forma Scientific Bio Freezer, Mod. 8326 for a total of 7.2 kWh/day saved.
    • 12.2 kWh/day (at -80 ⁰C) to 9.2 kWh/day (at -70 ⁰C) on an more energy efficient upright New Brunswick Eppendorf HEF U570 Freezer for a total of 3 kWh/day saved.
    • 16.1 kWh/day (at -80 ⁰C) to 14.1 kWh/day (-70 ⁰C) on a chest freezer VWR Model #5459 (Thermo Forma) for a total of 2 kWh/day saved.
    • The Green Lab Program at UC Davis has additional data on metering of ULT freezer units here.

What kinds of samples can safely be stored at -70 ⁰C?

Scientists at CU Boulder and UC Davis have contributed to a database of cold sample storage practices to demonstrate sample types that are being stored at -70 ⁰C. Please note that this database is not science-based data on appropriate temperatures for samples, though these temperatures have been successful for various labs for years. You can access the CU Boulder and UC Davis cold sample storage practices database at this link. 

Did you know that before any ULT freezers could be manufactured to reach -80 ⁰C, ULT freezers were only able to reach -70 ⁰C?  To best of our knowledge, the switch from -70 ⁰C to -80 ⁰C was a result of marketing by manufacturers to sell ULT freezers rather than a demonstrated scientific need for -80 ⁰C for samples stored in ULT freezers.

Don't be so cold poster

At the International Institute for Sustainable Laboratories (I2SL) conference in September 2013, a presentation by the CDC included the fact that they raised 60 of their ULT freezers to -70 ⁰C from -80 ⁰C on one of their campuses as part of the freezer challenge. Click here for a link to the CDC's I2SL abstract. 

The University of Edinburgh in the UK is currently conducting a study to scientifically address the question of what temperatures are most appropriate for certain sample types. They hope to store their samples at either -60 ⁰C, -70 ⁰C, or -80 ⁰C for a minimum of five years and then test their viability. This is an exciting study, and we look forward to learning about the results in a few years!

Outside information on sample storage temperatures:

Additional Resources:

Ashlyn Norberg gave a presentation at a recent I2SL conference highlighting how CU Green Labs was able to convice scientists to raise their freezer temperatures to -70 ⁰C from -80 ⁰C. Check out Ashlyn's presentation by following this link.

Title slide of presentation for I2SL conference Sticker indicating that a particular ULT freezer is at -70 celsius instead of -80


Join your colleagues by exploring whether -70 ⁰C is appropriate for your samples too!