Start with the required storage temperature
Read the label, kit insert, study protocol or SOP. If it says 'store at or below −70 °C' or gives a range such as the −90 to −60 °C ultra-cold band described in US CDC vaccine guidance, a −60 °C freezer is not enough, whatever the price difference. If it says −20 °C or −40 °C, an ultra-low cabinet may be wasted energy.
Where the requirement is 'frozen, below −50 °C' or similar, a −60 °C class freezer may be a sensible fit. Confirm with whoever owns the requirement before buying.
How the two classes compare
| Aspect | −60 °C class | −80 °C class |
|---|---|---|
| Typical refrigeration | Single-stage or two-stage, depending on design | Usually two-stage cascade or specialised systems |
| Energy use | Lower for the same volume | Higher; the gap to room temperature is larger |
| Heat into the room | Moderate | High — room ventilation or air-conditioning matters |
| Pull-down and recovery | Generally quicker to reach set point | Slower after loading or door openings |
| Format | Often chest style | Upright and chest |
| Common uses | Long-hold frozen goods, some reagents and samples rated for this range | Biobanks, long-term biological samples, products labelled for ultra-cold storage |
Why some samples need colder
Lower temperatures slow chemical and biological change. For some materials, the slower rate at −80 °C over many years of storage is what preserves them; for others, −20 °C or −60 °C is already enough. Reviews of lab practice have noted that direct comparisons of sample stability at −70 and −80 °C are limited, which is why the decision must rest on product data or protocol, not habit.
Margin also matters. A sample that must stay below −60 °C has more buffer in a −80 °C freezer during a door opening or a short power cut than in a freezer running right at −60 °C.
Energy and room considerations
Each degree colder costs energy. MIT's lab guidance says moving ULT freezers from −80 to −70 °C can save up to 30%; the step to a −60 °C class freezer is larger again. In India, where many labs run without round-the-clock air-conditioning, the heat a −80 °C unit puts into the room also affects the next freezer and the people working there.
Check the rated ambient for both options. A freezer that holds −80 °C in a 25 °C room may not hold it in a 35 °C one.
Chest or upright
- Chest freezers hold cold air when opened and usually hold temperature longer after a power cut.
- Upright freezers save floor space and make racked inventory easier to reach, at the cost of more cold air lost per opening.
- For long-hold storage with infrequent access, chest designs are often more forgiving.
- For daily-access sample storage, uprights with inner doors limit the cold lost per opening.
A quick decision guide
- Product or protocol says ≤ −70 °C or −80 °C: choose a −80 °C class freezer.
- Requirement allows −60 °C or warmer and access is infrequent: a −60 °C class freezer can cut energy and cost.
- Mixed requirements: store each product in a freezer that meets its own requirement, rather than running everything at the coldest setting.
- Unsure: ask the product owner or supplier for written storage conditions before buying.
Where KALT fits
KALT's deep freezer family covers −18 °C down to −60 °C. That suits applications whose requirement sits within that range; it is not a substitute for a −80 °C freezer where the product or protocol needs colder. Ask us for the specification of a particular model and compare it against your written requirement.
Frequently asked questions
- Can I run a −80 °C freezer at −60 °C to save energy?
- Often yes, and it will use less energy, but only if every product inside is rated for that temperature. Check labels and protocols first, and record the change in your SOPs.
- Is −60 °C cold enough for mRNA vaccines?
- Requirements differ by product. Some are labelled for ultra-cold storage in the −90 to −60 °C range; others have different conditions. Always follow the product's own storage statement and your programme's guidance.
