The Downside of Open Air Refrigerated Display Cases

open air merchandising case
Display cases can be convenient for customers, but a hit on your bottom line.

Open air refrigerated display cases commonly seen in grocery stores can provide easy access to products for customers. The main problem with these refrigerators is that they are constantly fighting the ambient air, causing their refrigeration units to work much harder than if they were enclosed. They also increase heating bills for grocery stores in the winter as they constantly dump cold air into the heated building. You’ll know this to be true if you’ve ever caught a chill while walking through grocery aisles with display cases. Grocery stores are starting to catch on to the benefits of walk-in coolers and substituting glass-door merchandising walk-ins and walk-in dairy rooms for these cases. The following article details the energy saving efforts of a grocery store chain in Britain.

Makro is to install walk-in dairy rooms at 17 of its 30 cash & carries by the end of the year.

The move is part of an energy saving drive which will enable pubs to source supplies with a smaller carbon footprint. The dairy rooms save energy compared to fridges and chillers in the main store area.

An energy saving experiment for your grocery store

A research study at Kettering University in Michigan investigated how to make an open refrigerated display case (like those found in grocery stores) operate more efficiently.  The study concluded that raising the temperature setting while lowering the air velocity from the refrigeration would not only provide energy savings, but the food was actually kept cooler.

Lower infiltration [of warm air] means the air is coming out at a lower velocity, said Navaz. “Previously, air came out of the upper vent (or grille) of a specific display case at 90 feet per minute. We calculated the optimal speed as 65 feet per minute as an optimal discharge air velocity to yield lower infiltration rate,” he said.

By reducing the velocity by 30 percent, infiltration was reduced by 12 percent and the power required was reduced by 13 percent.

Increasing the temperature at the discharge air grille by about 1 degree (F) and lowering the velocity of air resulted in lower suction pressure at the compressor inletwhich reduced the compressor usage and therefore less energy consumption.

Infiltration represents 83 percent of the cooling load and is the biggest draw on energy of refrigerated display cases. Less energy use translates into real cost savings to the tune of about $13 million for the state of California alone, according to Navaz.

In addition to energy savings, lowering the pressure on the compressor also extends the life of the compressor and creates more cost savings over the long term.

Click here to read the entire Kettering refrigeration study.