Outside information on energy savings at -70 ⁰C:
- Advocates for energy efficiency in laboratories have suggested that increasing ULT freezer temperature from -80°C to -70°C can reduce energy usage while maintaining performance. This study corroborated that view, finding that such a temperature change reduces energy consumption by an average of 37% for both standard-efficiency and energy-efficient ULT freezers without any discernable effect on temperature stability. Full Reading available here.
- A representative from Thermo Fisher Scientific mentioned to Allison Paradise at My Green Lab that they have unpublished data supporting the fact that it takes 1 to 1.5 hours less time for an empty ULT freezer at -70 ⁰C to warm up to -50 ⁰C than if the freezer’s set point had been at -80 ⁰C. The representative reported that on average the warm up time went from about 300 minutes to about 235 minutes when you changed the setpoint from -80 ⁰C to -70 ⁰C. For a full freezer, the warm up difference between a freezer set at -80 ⁰C and one set at -70 ⁰C is only 30-40 minutes.
- At the University of Copenhagen, freezers were evaluated on the basis of Total Cost of Ownership with focus on energy consumption. Four different models were tested at both -70 C and -80 C under controlled conditions at an external certified laboratory. Results of the tests include 20-22% lower energy consumption at -70C for new ULT freezers and inner temperature being more reliable at -70C than -80C. Additionally, upright freezers are in average 22% more efficient by volume than chest freezers, and large freezers are in average 13% more efficient by volume than small freezers.