14 January 2020

PLEN raises the freezer temperature

Sustainable labs

Energy savings of 20-22%, longer service life and fewer expenses on new freezers in the laboratory budget – without negative impacts on research. Just by raising the freezer temperature by 10 degrees.

Particularly sensitive biochemical samples are stored in Ultra-low temperature freezers (ULT freezers) at minus 80 degrees Celsius, and that’s just how it is! Or so it was at the Department of Plant and Environmental Sciences, but this is now changing to save energy and extend the service life of freezers. The Department is now setting the freezer temperature at minus 70 degrees rather than minus 80 degrees – for the benefit of the environment as well as the bottom line.  

Postdoc Nikolaj Lervad Hansen, Assistant professor Allison Heskes and Precision Engineer Flemming Frederiksen

In the Section for Plant Biochemistry, they have taken the consequences and raised the freezer temperature. 

 “It all started when we read in a laboratory magazine that many laboratories are raising the freezer temperature at present,” says Niels Agerbirk, plant biochemist. 

 But there was some way to go from a decision in principle to practice, and that is where laboratory coordinator Tilla Engelsted and precision mechanic Flemming Frederiksen played a key role:

 “We could find no evidence for either minus 70 or minus 80,” says Tilla Engelsted. 

 Minus 80 degrees is an informal scientific standard for the temperature for storing biochemical samples. The standard has arisen because it became possible to produce freezers with gradually lower temperatures. This is how the temperature landed at minus 80 degrees – or in some cases minus 86 degrees. 

“Since there is no evidence for either minus 70 or minus 80 degrees, we might as well choose the energy and climate-friendly option,” says Tilla Engelsted. 

Through tests, Green Campus has documented energy savings of 20-22% by setting freezers at minus 70 rather than minus 80 degrees. But that’s not the only upside. At minus 70 degrees, less energy is needed to cool the freezer rooms, with substantially less pressure on the compressors. As a result, the expensive freezers last longer. 

 “The motivation for the change was driven by climate considerations – and long-term financial considerations, because the freezers last longer,” says Tilla Engelsted. 

The faculty footing the energy bill also obtains substantial savings – in terms of carbon emissions and en-ergy costs. When new freezers are purchased, emphasis is now placed on ensuring that they perform well at minus 70 degrees. UCPH’s procurement contract for ULT freezers allows for this consideration – and, at the same time, the freezers are more energy efficient than others on the market. 

Tips for the freezer

  1. ​​​Set the temperature at minus 70 or minus 75 degrees rather than minus 80 degrees (for new freezers, but consult the manual before tampering with anything!)
    • ​There is as much evidence for minus 70 degrees as there is for minus 80 degrees for continuous storage of samples
    • This produces annual energy savings of 20-22%
    • The freezers last longer

​2. ​Do an annual review and clean-up

3. Clean the freezers regularly (especially filters and compressors). Share the facilities – use freezers across department

4. Use UCPH’s procurement contract for the purchase of new freezers