When U.S. grocery chain Lunds & Byerlys installed its first transcritical CO2 (R744) refrigeration system in White Bear Lake, Minnesota, in 2018, it expected to save energy.

But the chain got more than it bargained for, saving 22% in total store energy during 2020, compared to a similar store in Edina, Minnesota that uses an R407A DX system. And the transcritical CO2 store experienced savings every month of the year, including July when the average temperature goes up to 85°F (29.4°C).

“It really opened our eyes,” said Jeff Carlson, a Service Technician at Lunds & Byerlys. “We knew that there’d be energy savings for 10 months out of the year, but we thought we’d be pretty neutral in July and August … but we were able to save energy year round.”

Carlson shared these findings during an online end-user panel discussion at the ATMO Virtual Trade Show (VTS) on natural refrigerant technologies on March 30. ATMO VTS was organized by shecco, publisher of R744.com.

The energy savings has given Lunds & Byerlys a taste for more, and the chain is now planning to install CO2 refrigeration in three new upcoming stores, including one that opens next month.

The comparison store in Edina, which opened in 2015 is roughly the same size as the White Bear Lake store, and both have the same electrical footprint with hot food bars and salad bars. The cooling capacity of the Edina store is 5% higher than the White Bear Lake store.

Refrigeration-only analysis

The 22% in energy savings Lunds & Byerlys have experienced is for the total store, not just refrigeration. When looking at the energy for the refrigeration system only, the R407A system was found to be 16% higher in energy (kW) usage than the transcritical system between September 2019 and April 2020, with a 13% lower EER (BTU/W).

The White Bear Lake store is equipped with a Hillphoenix Advansor transcritical CO2 system. The system has a low-temperature capacity of 178 MBH (-16°F/-26.7°C) and a medium-temperature capacity of 580 MBH (19°F/-7.2°C). The store also uses Hillphoenix cases, a Baltimore Aircoil Company (BAC) adiabatic gas cooler and RDM (Resource Data Management)system controls. The transcritical system does not use parallel compression or ejectors.

The Lunds & Byerlys transcritical CO2 system is the first in the U.S. to use RDM  controls.

Lunds & Byerlys contractor for the transcritical CO2 installation was Minneapolis, Minnesota-based South-Town Refrigeration & Mechanical.

Its energy consultant was Singh360, in Medina, Minnesota.

““We knew that there’d be energy savings for 10 months out of the year, but we thought we’d be pretty neutral in July and August … but we were able to save energy year round,”

Jeff Carlson

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