Significantly lower laboratory energy consumption in your research organization with Stirling Freezer technology

Lowest energy use, heat rejection and operating cost.

Until the introduction of the Stirling free-piston engine ultra-low temperature (ULT) freezer technology saw little change or improvement over the last five decades.  And yet, compressor-based freezers demand large amounts of power to operate . . . as much as the average U.S. home! Now there is a more cost-effective and energy-efficient freezer alternative with Stirling Ultracold. Consider the cumulative savings of replacing multiple compressor-based ULTs with Stirling energy-efficient freezers . . .

Stirling Ultracold ultra-low freezers use significantly less energy to operate than the standard compressor-based system. Our models also reduce HVAC requirements because they reject less than one third the heat of typical compressor-based ULT systems. The reduced heat also means researchers will be more comfortable when working near the Stirling freezers.

At -80° C, the Stirling Ultracold SU780XLE upright freezer uses 70-75% less energy than standard compressor-based ULT freezers. That translates into immediate savings in laboratory energy consumption and costs that are significant over the freezer’s life.


The SU780XLE is the most energy-efficient ENERGY STAR®-certified ULT freezer At 6.67 kWh/day (.29 kWh/day/cu-ft.)

There are many different ways to test ultra-low freezers. Until recently, this lack of a test standard had made it impossible for ULT buyers to accurately compare the energy use of different models. Efforts by the EPA and manufacturers produced the industry-standard Final Test Method, used as the certification for ENERGY STAR® freezers.  Stirling Ultracold was the first to submit energy test data to the EPA for the industry leading SU780XLE using this new industry standard.  Now that other freezers have also submitted their data, the EPA has created the laboratory grade ultra-low freezer category. Please visit to review these standardized results.  There you will find that the SU780XLE is certified as the most energy-efficient ULT freezer (.29 kWh/day/ft3).

Earn utility rebates with the SU780XLE

These advantages have also been noted by several electric utility providers who have begun offering custom utility rebates for replacing compressor based cascade freezers with Stirling units. While savings will depend on how many freezers you replace, and the specific rebate your energy provider offers, some Stirling Ultracold users have already been awarded hundreds of dollars per freezer by utilities and through internal energy/sustainability initiatives. Contact your Stirling Ultracold account manager to get help with the rebate application process for your utility.