Types of Laboratory Freezers
Standard laboratory freezers are maintained for sample and reagent storage in the 0°C to -25°C range. Low-temperature freezers can maintain temps as low as -40°C and ultra-low-temperature (ULT) freezers are important for samples that must be maintained lower than that, generally between -65°C and -86°C.
In addition to temperature options, freezers come in different sizes and shapes and with a range of new technologies. Sizes can range from mini freezers that fit on top of or under the lab bench to large freestanding freezer units with more than 30 cubic feet of storage. Large freezers can be upright units with doors that swing out - much like a refrigerator or freezer at home - or chest freezers that lie horizontally and have lids that lift up, like most ice chests.
Beyond size and shape, there are many different storage configurations available, locking mechanisms, defrost programs, and units equipped with touchscreens and other newer technologies.
Energy consumption: .75 kWh/day/cu-ft
Energy consumption: .41 kWh/day/cu-ft
EPA ENERGY STAR® Program
The US Environmental Protection Agency (EPA) has created specifications for energy-efficient refrigerators and freezers for laboratory use. The goal of this program is to make it easy for consumers to identify appliances that will be environmentally friendly by consuming less energy while also saving energy costs for the user. Most manufacturers that are eligible will include the ENERGY STAR® label, making it an easy way to spot freezers that meet these criteria. You can also search an online database to determine whether the unit you’re looking at complies with ENERGY STAR® guidelines. The following ENERGY STAR® Program requirements for energy consumption must be met in order for a brand to include the ENERGY STAR® rating on their product(s):
ENERGY STAR® guidelines for energy consumption for standard (Table 2) and ultra-low temperature (Table 3) laboratory freezers.
Upright vs. Chest Freezers
In general, chest freezers are more energy efficient than upright freezers. There are a number of reasons for this, including limited air circulation compared to upright options, reduced temperature fluctuations following door openings, and manual defrost programs that reduce energy consumed compared to automatic defrost programs. However, it is important to check the Energy Star® label and/or listed energy efficiency as advances in compressor and cooling system technologies, seals, and insulation have made a big difference in energy efficiency for both chest and upright freezers. An upright unit with a manual defrost program may be as energy efficient - or more so - than its chest freezer counterpart.
With energy consumption of only .29 kWh/day/cu-ft, the 29.2 cu. ft. Haier Ultimate Energy Saving ULT Upright Freezer is ENERGY STAR® rated. This model also uses R-170 and R-290 refrigerants.
There are pros and cons for both upright and chest freezers. Chest freezers take up more floor real estate, accessing samples may be more difficult, and manual defrosting is required. They are also more temperature stable and less sensitive to temperature fluctuations when the door is opened, which is critical for certain clinical or other temperature-sensitive samples. Upright freezers tend to be noisier, take up less floor space, and offer more convenient options for organizing and accessing samples when compared to chest freezers.
Requires more floor space
More options for sample storage and organization
Sample access may be more difficult
Less stable than chest freezer options. It takes longer to recover temperature following door opening. If door shelves are present they will be particularly susceptible to temperature fluctuations
More stable than upright freezers. Quicker recovery time following door opening; less cold air loss. Greater temperature uniformity.
Manual or auto defrost options
Manual defrost options only; improves efficiency, but requires more effort
Noisier than chest freezers
Less noisy than upright options
Best Practices for Energy Efficiency
The way lab personnel use a freezer will also impact its efficiency.
- Limit door openings and duration of door openings
- Keep detailed, up-to-date records of stored samples, including their locations within the freezer unit, and reagents, including their expiration dates and locations to limit the time needed for door openings.
- Regularly clear out and discard unnecessary samples and expired reagents
- Unplug unneeded freezer units
- Remove dust or debris from intake and coils
- Remove accumulated frost and/or ice to increase the time between full defrosts
- Perform full manual defrosts when necessary to avoid system failure and compromised samples
- Use high-density storage options: use 13 x 13 dividers in storage boxes rather than 9 x 9 or 10 x 10 and fill the entire box before utilizing a new box; use smaller tubes where possible.
Other Environmental Impacts
If looking to maximize sustainability beyond daily energy consumption, there are many other aspects to consider. Some of these include:
- Manufacturing processes
- Energy source for manufacturing
- Refrigerants used
- Chemical storage and disposal
- Shipping and shipping materials
- End-of-life disposal
There are some helpful labels and certifications that can help you select a more sustainable freezer solution. The ACT Environmental Impact Factor Label certification analyzes many environmental aspects including manufacturing factors and end-of-life. This certification assesses products on a scale from 1 (good) to 10 (bad) and provides an overall score. The website has a searchable database of laboratory equipment. The European Union (EU) banned the use of fluorinated gases, referred to as EU F-GAS regulations. The US EPA Significant New Alternatives Policy (SNAP) requires the use of substitutes for ozone-depleting substances to reduce overall risk to human health and the environment. Some manufacturers will list their compliance with some or all of these regulations. Additionally, information about refrigerant use and other sustainability factors can be found in the EPAs searchable online database.