Freezer Challenge CompetitionFreezer that needs defrosting

Cornell participates in the annual International Laboratory Freezer Challenge, hosted by the International Institute for Sustainable Laboratories (I2SL) and My Green Lab. Participating labs compete against fellow Cornell laboratories and campuses from around the world as they are guided in implementing best practices in cold storage management to achieve greater energy efficiency, sample integrity, and sample access.

What should I know before I sign up?

The Freezer Challenge provides participating labs with simple solutions on a weekly basis to save energy. You are then prompted to record success in order to compete with other labs!

  • WHO: All laboratories from all sectors with cold storage can participate.

  • WHEN: Register by April 30th. Competition runs from April 30th to June 30th.

  • PRIZES: All participating labs will be entered to win a deluxe pizza party for their teams. Winners of the international competition will be recognized in Nature Magazine and at the 2022 I2SL Conference in September.

  • QUESTIONS? Contact info@mygreenlab.org or sustainability@cornell.edu

Why should I participate?

Laboratories are the greatest source of energy use on campus. That means lab spaces have a huge impact when implementing energy efficiency measures. By reducing energy waste, we save money and carbon emissions that contribute to climate change, helping Cornell reach our goal of carbon neutrality by 2035.

Across 2 years of participation Cornell labs has saved 86,000 kWh per year. 222 labs from over 100 different research institutions participated this year, representing 17 countries. The combined efforts of the scientists and labs participating in the 2021 Freezer Challenge saved 4.6 million kWh of electricity over the past year, which is the equivalent of reducing carbon emissions by 3,260 metric tons.

Get your laboratory engaged with doing science in more sustainable ways – the Freezer Challenge benefits your research and the planet.

Campaign Goals

Ultra Low Freezers ULT) are ULTs are some of the largest energy consumers found in labs. Creating awareness of ULT maintenance and resources Cornell labs will contribute to reducing greenhouse emissions. As a result of a lab survey done earlier this year we are focusing on: Defrosting, Maintenance, Inventorying samples and Purchasing Choices.



Fast Fact 

ULTs 15 years or older use 28-35 kWh per day, as much energy as an average single-family home uses in a day


OUR GOALS AT CORNELL for this campaign include:

  • Defrosting ULTs 

  • Maintaining ULTs | Cornell Air Conditioning & Refrigeration Shop (ACR)
    Regular maintenance can reduce today's ULT freezer energy consumption by as much as half.

  • Inventorying Samples.
    Removal of unneeded or unviable samples from cold storage units, freeing up that space for new samples without having to purchase additional refrigerators and freezers.

  • Purchasing Wisely
     You can save $1,674 or more by buying ENERGY STAR.


Take Action

When, and how, to do a full freezer defrost?

Ice accumulation in a lab freezer may be the result of a serious problem, such as a leaky door gasket or too frequent door openings, but can also result from a lack of other preventative maintenance, such as not brushing the frost regularly. So when is it time for a full defrost of a unit?

If you have ice build-up thick enough that you can't brush or scrape it out, or you're having trouble accessing your samples, then it is definitely time for a Big Thaw.

You, like us, may have heard the myth that ice build-up in lab freezers is a good thing...that ice build-up 'proves that the freezer is working' or 'insulates the freezer when the door is opened'. Rather than protecting the freezer, in actuality, large amounts of ice may force your freezer to have to work harder than usual to maintain temperature, and it may lead to warm pockets because of poor air convection. Forcing your freezer to work harder is putting your unit, and precious samples, at risk.

If you have significant ice build-up, and can't easily brush it out, it may be time for a full defrost. Take an opportunity in the next four months during the 2022 Freezer Challenge to get this done, for the benefit of your whole lab. Note that if you have an auto-defrost freezer (like some -20 Cs), you may never need to do a full defrost.

First, Protect Your Samples
Find somewhere to temporarily store your samples, such as in a backup freezer for your department or institution, or by asking nearby labs if they have any space to spare. You may need to store your samples in multiple freezers to take advantage of available space. Alternatively, you can place samples in coolers with dry ice, though be sure to do so in a room with sufficient ventilation. For short-term safe storage of and entire freezer-load of samples, it is best to find available freezer space.

Do the Defrost!
We have gathered several resources on the Freezer Challenge website from the competition sponsors, as well as others like the National Institutes of Health, that provide details of how to do full defrosts of freezers. In addition, below are some step by step ideas for how to do a full defrost on a freezer.
  1. Before turning off your freezer, if you have a temperature monitoring system installed, be sure to alert whoever manages the alarm system to let them know you'll be powering down you freezer, so they can disable any alarms.
  2. Plan Ahead: Consider doing a defrost at the end of the work week so the freezer can remain off and ajar over the weekend to completely dry out.
  3. Remove all your samples from the unit, safely storing them in other freezers with available space.
  4. Place water collection basins, or absorbent towels in front of the freezer to collect any water that pools during the defrost process. Collapsed cardboard boxes can even work for this purpose - just ensure they fully dry back out before returning them to a recycling bin.
  5. Power down your freezer and unplug it.
  6. Prop the door open with a spare freezer rack or other object. 
  7. Let the freezer warm up and dry out over the weekend.
  8. Once completely dry, you can use a mild detergent to clean the freezer shelves and walls if desired.
  9. Close the freezer door and turn the unit back on.
  10. Clean up any water from the floor around the unit.
  11. Once the freezer reaches set-point again, you can put your samples back in the freezer. You may need to do this in batches to prevent large temperature fluctuations.
  12. If applicable, ensure your temperature alarm system gets reactivated once the defrost process is complete.

Final Thoughts
Removing ice from a freezer allows its compressors or engine to work more easily, which can lead to longer freezer life and reduced energy use. Though it takes a bit of effort on your part to do a full defrost, it should only be needed on an annual or biennial basis. If you have significant frost build-up more quickly than annually, consider having a repair technician come to check out your unit for other issues such as a broken gaskets or a door seal leak.

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Cornell University is working to centralize inventories of ultra-low freezers (ULTs) on campus to better understand energy usage and climate impacts of our ULT plug-loads, especially as they age. A centralized inventory will provide insights into how many freezers we have on campus, how they perform, and how they are managed. This will inform future energy conservation projects here at Cornell, as well as our campus participation in the annual Freezer Challenge.

We ask all labs to complete this ULT freezer survey during Summer 2022. Since we have hundreds of labs on campus, we need your help gathering information about ULTs in your specific lab(s). If you have an existing inventory, feel free to upload a copy within the Qualtrics survey to save time. All labs that complete the survey will receive enduring gratitude from our team and knowledge that you are contributing to a more sustainable campus.

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More resources for laboratories

Cornell University Green Lab Program

Cornell's Green Lab Certification assists lab users in reducing energy and material waste, and improving overall lab sustainability by providing a checklist of potential actions and levels of achievement to help celebrate accomplishments as a team. We have many materials already created to help you quickly identify energy, water, and other areas of impact.