Did you know that a standard -80°C ultra-low temperature (ULT) freezer can use up to the same amount of energy as an average Canadian household every day? Justifiably freezers are a vital component of not only our homes but our labs and therefore, there will always be uncontrollable energy consumption. But through regular freezer maintenance, ULT freezers and our freezers at home will not only operate better and last longer, but they will have a significant reduction in their energy consumption!

To put this into perspective, an unmaintained freezer can use up to 12% to 25% more energy than a maintained freezer. Let’s review 4 simple maintenance actions that you can do in your lab and at home to reduce energy consumption while lengthening their life!

  1. Changing the set point from -80°C to -70°C

It is understandable to be hesitant to change the temperature of your ULT freezer as it holds all your hard work over the past months to years. But it should be noted that over fifteen years ago, the standard practice for ULT freezer temperature was -70 °C and even -65°C! The more recent increase to the new -80°C standard has actually been more linked to marketing and selling of freezers from the vendors than proven science.

So, let’s look at the breakdown of savings just by changing the temperature by 10 degrees:

  1. Reduces up to 30% of energy consumption
  2. Will save about 2 to 4 kWh per day
  3. Will save over 1000 kWh every year
  4. Prolongs your freezer’s lifespan by decreasing how often the compressor turns on and off and thus, a less chance that your samples will be compromised

There is a time when the freezer temperature should not be changed to -70°C – when the freezer is partially full. Lower thermal mass leads to higher temperature swings when the freezer is opened. So, if you do choose to chill up your freezer when it’s not completely full, monitor it frequently.

At home, the same maintenance standards apply! Make sure your freezer temperature is set to -18°C as 1 degree colder increases your energy consumption by 5% – 10%. By doing so, you will increase the longevity of your freezer, keep your food lasting longer, while reducing your energy bills!

Peer-Reviewed Studies proving -70°C or warmer storage

2. Clean the dust from the filters and coils

About once a month, at home and at the lab, freezer filters should be checked to make sure they aren’t clogged with dust, cleaned, and replaced when necessary. When the filters are clogged with dust, it becomes more difficult for air to flow to cool the coils and less heat is extracted. Therefore, the condenser works harder by using more energy to cool the freezer, wearing it out.

  • Dusty ULT freezer filter

Cleaning the filter and coils is fairly simple and straight-forward both at home and at the lab! To clean the filter, simply remove it and rinse with water in the direction of the filter and place it back on the freezer (can even be put back on while it’s still wet). To clean the coils, gently vacuum, brush, or wipe with a wet paper towel the dust in the direction of the lines on the coils.

3. Open freezer door for a maximum of 1 minute

Did you know that for every minute that a freezer door is open, the compressor works for 10 minutes to re-establish the original temperature? That means if you are standing with the freezer door open for 2 minutes looking for a sample or looking for something to eat (I’ve definitely been guilty of this once or twice…), your freezer will have to work for 20 minutes to get back to the original temperature!

How can you limit the time your freezer is open? Keep a well-organized inventory of what is inside. This will reduce the time you need to look for the sample (or food at home) while simultaneously decreasing the risk of compromising the samples by exposing them to warmer temperatures. If the inventory is up-to-date, space isn’t wasted keeping samples that are no longer needed and home you have space for more food!

4. Periodically remove ice and frost

And finally, one of the more important things you can do is regularly defrost your freezer both at home and at the lab. On the energy side, this will help to reduce energy consumption as a layer of ice can increase energy consumption from anywhere between 10% to 50%! To clean the ice or frost build up, simply use a plastic device to scrape it off or use a damp cloth, making sure to not use any sharp devices like a knife. If there is significant build up, you will need to remove everything from the freezer, unplug it, and let it naturally defrost. But with frequent maintenance, this can be avoided!

You might be wondering how ice buildup is linked to energy consumption. Well, accumulation of frost creates gaps in the seals which allows cold air to escape and warm air to enter, affecting your samples or food at home! Therefore, the compressor must work harder to maintain the set temperature.

  • Unmaintained ULT freezer that needs the ice and frost removed to conserve energy and keep samples from being compromised.

Not only will this increase energy consumption but by putting pressure on the compressor to work harder to maintain the set point, the compressor will die sooner, and you’ll find yourself replacing your freezer sooner than you planned to.

Hopefully you not only were able to refresh your freezer maintenance knowledge for lab freezers but also learned that the same strategies can be used at home to save some $$ and your food!

Freezer Infographic

Be sure to check out the new Freezer Infographics posted on your -80 freezers throughout both PMCRT and KDT! If you have any questions related to switching your freezer for a more energy efficient one or about freezer maintenance, contact us at green@uhn.ca!