Green Education - How To Make Freezers Sustainable


Personal Note From Patrick, The Editor

Hi Reader, last week we found out that an ULT freezer leaves a footprint of up to 50 000 kg of CO2 in its lifetime.

Today, we will discover what we can do to reduce the impact of our cooling systems and how significant these measures can be.

I also created the first-ever chart showing how freezer energy consumption has developed over the last few decades for you.

Without further ado, let’s jump in!


Today's Lesson: Saving Energy with Freezers

What you can do to reduce the impact of your freezers


Number Of The Day

The global freezer market in 2022 was estimated at a staggering $4.7 billion. However, by 2030, estimates predict it will grow to between $7.4 billion and $12.7 billion. While the EU and US markets are the largest, Asian markets are expanding rapidly. Nevertheless, it is notable that Africa and South America—despite having significantly hotter climates—accounted for less than 5% of the market in 2024.

4 700 000 000


Making Freezers More Sustainable

As we discussed in our last lesson, the biggest environmental impact of ultra-low temperature (ULT) freezers comes from their use phase.

But how big is their energy consumption compared to other lab equipment?

The average energy consumption of a freezer per year ranges between 2.5 - 9.1 million Wh. An average American household consumes between 9 and 11 million Wh per year. Thus, only the older models consume more energy than an entire home!

Now that we have a sense of scale, let’s explore how to minimize freezer energy consumption as much as possible.

Purchasing

At first, choosing a freezer with lower energy consumption will be environmentally beneficial.

Modern ULT freezers have become significantly more energy efficient over the past few decades.

A 500+ L model from before 2000 can be expected to use up to 36 kWh/day, whereas models from the 2000s–2005s typically consume around 19 kWh/day.

More recent models have further improved efficiency, consuming between 7–12 kWh/day, with the most efficient freezer currently available (PHCBI) using just 4.99 kWh/day.

These efficiency gains are the result of multiple technological advances:

  • Improved heat exchange designs optimize cooling performance.
  • Vacuum-insulated panels have replaced polyurethane foam, reducing heat loss.
  • Variable-speed and dual-stage compressors adjust power dynamically, operating only at the minimum required level rather than running at full power constantly.

However, even the best freezers age. Every year, energy consumption increases by approximately 1-3%, which can easily translate to an additional 8.75 kg of CO₂e per month.
A summary of when to purchase a new freezer can found in our free Slack.

Adjusting Set Temperatures

The single most impactful change a lab can make is adjusting freezer temperatures from -80°C to -70°C or lower.

Based on studies from the University of Copenhagen, together with an investigation by Farley et al., and manufacturer data, we can confidently say that raising the temperature from -80°C to -70°C reduces energy consumption by 22–29%!

In fact, -70°C was the standard for decades before improvements in cooling technology made -80°C the norm—not for scientific reasons, but because it became a marketing advantage.

Published studies further confirm that sample stability is not affected:

  • Espinel-Ingroff et al. successfully recovered 6,000+ yeast and 300+ mold samples after 10 years of storage at both -70°C and -80°C.
  • Landor et al. found no significant degradation in DNA and RNA stored at -70°C, with only minor 260/230 ratio variations, all well below standard deviation ranges.
  • Paraoxonase-1 enzyme activity remained unchanged after one year of storage at -70°C.

Even manufacturers acknowledge this—QIAGEN officially recommends storing RNA at -70°C.

And it’s not just ULT freezers—adjusting standard freezers from -25°C to -20°C has been shown to reduce energy consumption by 20%, as reported by EPFL in Switzerland.

The Role of Proper Setup and Maintenance

Aside from temperature adjustments, proper installation and maintenance can significantly reduce a freezer’s energy consumption.

A study by Gumapas et al. analyzed four freezers (20–25 kWh/day) under different conditions and found several key factors:

Controlling Ambient Temperature

  • Each 1°C increase in room temperature leads to 18 kWh of extra energy use per month, releasing an additional 9.27 kg of CO₂e. (+ don't place freezers at windows/in the sun)

Avoiding Dust Accumulation

  • Regular cleaning can save 211 kWh per month, preventing 108 kg of CO₂e emissions.

  • Declogging filters alone reduced energy consumption by 117 kWh per month, or 60 kg of CO₂e.

Ensuring Ventilation

  • In their case, poor ventilation increases the duty cycle by 4%, leading to an additional 85 kWh of electricity used per month (equivalent to 51 kg of CO₂e).

Removing Ice

  • Heavy ice accumulation can increase energy use by up to 50%, forcing the compressor to work harder to maintain low temperatures.
    (Next week more on how to clean your freezer)

Applying The Knowledge

Should You Purchase Larger Freezers?

Older studies suggest that larger freezers were more about 13% for efficient. However, this depends on the manufacturer. While such a difference is still exists for PHCBI models, they do not in Eppendorf ULTs.

Of note, upright freezers tend to consume less electricity than chest freezers.



How to Convince Colleagues to Switch to -70°C

If your lab is hesitant, the best strategy is to start with one freezer and demonstrate that it is completely safe.

In fact, due to reduced compressor load, freezers set to -70°C are less likely to fail under suboptimal maintenance or when air conditioning struggles to keep up.

If you would like to demonstrate how much money can be saved though purchasing more efficient freezers, PHCBI has a simple online tool (just note that their competitors have newer models with smaller energy consumption).

Upcoming Lesson:

How to Maintain Freezers


How We Feel Today


References

Gumapas, L., Simons, G., 2012. Factors affecting the performance, energy consumption, and carbon footprint for ultra-low temperature freezers: Case study at the National Institutes of Health. World Review of Science, Technology and Sustainable Development, (), –. doi:10.1504/WRSTSD.2013.050786.

Espinel-Ingroff, A., Montero, D., Martin-Mazuelos, E., 2004. Long-term preservation of fungal isolates in commercially prepared cryogenic microbank vials. J. Clin. Microbiol., 42(3), 1257–1259. doi:10.1128/JCM.42.3.1257-1259.2004.

Landor, L.A.I., et al., 2024. DNA, RNA, and prokaryote community sample stability at different ultra-low temperature storage conditions. Environ. Sustain., 7, 77–83. doi:10.1007/s42398-023-00297-2.

Beekhof, P.K., Gorshunska, M., Jansen, E.H., 2012. Long-term stability of paraoxonase-1 and high-density lipoprotein in human serum. Lipids Health Dis., 11, 53. doi:10.1186/1476-511X-11-53.


If you have a wish or a question, feel free to reply to this Email.

Otherwise, wish you a beatiful week!
See you again the 27th : )

Find the previous lesson click - here -


Edited by Patrick Penndorf
Connection@ReAdvance.com
Lutherstraße 159, 07743, Jena, Thuringia, Germany
Data Protection & Impressum

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