FINAL REPORT: Optimizing the New Generation of Grocery Refrigeration Equipment

This project sought to gather information about the most important energy efficiency options applicable to carbon dioxide (CO2) refrigeration systems in Minnesota’s grocery stores. To provide Energy Optimization and Conservation (ECO) program decision-makers with the key information needed to develop the most effective programs possible for CO2 refrigeration systems, the project team conducted a market and technology assessment, followed by field-testing at three sites and a subsequent market check-in with key contacts near the end of the study. 

The field project took place over a three-year period and investigated three installations of the most currently relevant CO2 system upgrade options for grocery stores in Minnesota: adiabatic gas coolers, mechanical subcoolers, and a flooded evaporator option called FTE. The team verified energy and demand savings for all three technologies. FTE/flooded evaporators had about double the annual energy savings of the other two measures, but half their summer demand savings. They also found that lowering an adiabatic gas cooler’s wet-dry switchover point from 75°F to 55°F tripled the annual energy savings achieved.