It is not too often that the world of supermarket refrigeration has played host to major technological change. Apart from the debate over whether chiller cases should have doors on them, recent years have been more about evolution than revolution.

But now, retailer Asda, part of the global giant Wal-Mart, has signaled what could be one of the most radical changes in modern retail refrigeration by opting to replace conventional display cases cooled by piped refrigerant with versions cooled by air from a central plant.

By rolling out the Mistral Air system, developed by installing partner CBES across its stores, the retailer aims to "take the service engineer from the sales floor." Without piped refrigerant, and the fans and condensers of the display case, maintenance call outs can be reduced significantly.

But according to Brian Churchyard, Asda’s senior manager for construction design standards, who has been driving the strategy, what has convinced him to specify Mistral Air as the retailer’s model system of choice has been the fact that the latest systems now claim an energy savings of close to 15 percent over conventional models.

When the partners started development of the Mistral Air in 2012, it was energy-neutral, Churchyard says. However, as it is now on its fifth generation, the system has been achieving 11 to 15 percent over the conventional design.

Now that the energy gains have been established, the incorporation of the central plant, air handling unit and ducting system together enables a host of other benefits to be achieved, starting with refrigerant management. Refrigerant leakage is taken away from the shop floor and the refrigerant itself is confined to the plant room.

"That provides a huge amount of flexibility – we can be refrigerant agnostic. We could even use ammonia, if we took the appropriate plant risk management approach," Churchyard said.

Furthermore, by switching to an air handling system, the refrigerant charge can be reduced by as much as 40 percent. Doing away with the in-store refrigerant circuit also has a potentially dramatic effect on store hand-over, since removing the pressure testing element can save between 24 and 48 hours on commissioning.

Additionally, because the refrigeration plant is separate from the air handling unit, the whole system does not have to upgraded or replaced at the same time.

Set out in a list, the benefits that the partners believe Mistral Air brings are pretty extensive:

• Health and safety is improved considerably as there are no more drain leaks that result in water on the floor; a common problem associated with refrigerated display cases.
• The display cases have no serviceable components - taking engineers away from the sales area and eliminating operational noise to improve the customer experience.
• The need for de-merchandising is thus reduced, saving retailers’ time and minimising customer disruption
• Cold spillage is reduced from cases, resulting in warmer aisles.
• Cases are free from direct CO2 emissions and reduce refrigeration system energy consumption by 15 percent.
• The case design introduces a "plug-and-play" opportunity, as cases can be swapped without the need for the checks required with refrigerant, such as nitrogen purging. The partners contend this “dramatically increases flexibility and pace of change and reduces disruption during store modernisations."
• As the cases are not subject to water leaks or moisture damage their life expectancy is "double that of any other refrigerated display case," the partners say. This, along with the energy benefits and reduced display case maintenance, offers an estimated 19 percent cost saving over a 20-year period.
• From a refrigeration legislative perspective, Mistral Air is compliant and future-proof, because any refrigerant can be used in a modular, cost-effective roof-mounted plant solution.

But it is the scale of the energy benefit that has come as a surprise – even to those involved in the development. The gains are presumed to arise from removing the disruptive effect of the components in the cases on the air flow.

"It is now clear there are inherent inefficiencies with case components, but we simply hadn’t had the opportunity to test previously, because we had to have them in conventional systems. With them removed, we have a very linear air movement," Churchyard said.

Given that display case manufacturers don’t actually yet know how efficient they can make cases under the new system, the next phase for the partners is to see whether the refrigeration plant can be reduced further in size. Asda is running the system in an open trial setting in the belief that other retailers will be able to collaborate on refining and developing the technology.

The decision by Asda to embrace the system as its model spec will undoubtedly cause ripples throughout the industry – an industry used to equating display refrigeration with brazing, nitrogen purging, leak inspection and the like – and it is this which the U.K. cooling industry will be watching with interest.

There is no reason why the system should remain a U.K. retail technology, either. There is revolution in the air.