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Project Launch: 02/01/2021

Partners: National Renewable Energy Laboratory (NREL)

NREL’s research partnership with ComEd examined the technical aspects and potential energy savings of new generation high efficiency self-contained water-cooled medium temperature display cases.


The use of reach-in refrigerated display cases is widespread in supermarkets and convenience stores across ComEd’s service territory. This study assessed the energy savings resulting from retrofitting only self-contained units, converting from traditional air-cooled remote refrigeration systems to liquid-cooled self-contained systems. The results demonstrated this technology could yield significant energy savings and expand the market for these types of refrigeration systems in ComEd’s service territory.

Results and Outcomes

Retrofitting the baseline air-cooled, constant-speed system with the water-cooled, variable-speed ECM generated daily energy savings of 34.5 percent and 53.6 percent under 55ᵒ F and 80ᵒ F inlet water conditions. Water temperatures at or below 80ᵒ F are realistic for the majority of installations in the ComEd territory. At all temperatures, the ECM provided more consistent cooling, and did not cycle off except for defrost. Customer adoption of liquid-cooled condensing units in supermarkets and convenience stores across ComEd’s service territory is expected to reduce commercial refrigeration energy use.