Refrigeration experts in the U.K. have called for the industry to embrace the potential of "lower flammability" hydrofluoro-olefin (HFO) blends, as the F-Gas regulations continue to drive the European market towards lower-carbon solutions — and as the Kigali amendment begins to do the same for the global market.

The call has been driven by supermarket giant Asda (part of the Walmart group), which has successfully conducted an in-store installation with the refrigerant R454A, an HFO with a Global Warming Potential (GWP) of 238.

The installation is being hailed by Asda as a "world-first" in that not only has the retailer reduced its GWP, but it has achieved operational costs better than the available alternatives, such as CO2.

It is the first use in a supermarket refrigeration setting of the “very low-GWP” HFO blends that are classified as A2L or "lower flammability."

The use of the phrase "very low GWP" is being coined for refrigerants that are only slightly outside the "ultra-low" designation of under 150 GWP.

The store in Trafford Park, Manchester, U.K., has been hailed by Asda’s head of construction and design standards Brian Churchyard as the "world’s first truly commercially viable [retail refrigeration] HFO system."

The move is expected to have consequences for the wider industry because Asda has announced its willingness to use its work on the development of the A2L system as the platform for an industrywide standard.

Speaking at RAC’s F-Gas Question Time on Oct. 9, he said: "Our aim is to create an A2L design standard over time so any lower flammability HFO can be used…As an industry we need to appreciate that what the F-Gas regulations have given us are refrigerant options that are either flammable, toxic or explosive, so we need to mitigate the risks."

The R454A system at Trafford Park consists of a medium temperature application under 40 kW in capacity and below the 54 kg charge limit required by European Standard EN 378, and a low temperature application of around 15 kW capacity with an 11 kg refrigerant charge.

Asda’s confidence that it has the blueprint for an A2L refrigeration system stems from the fact that the Manchester installation has only come about after comprehensive trialing on a test installation at its Leeds site. It field-tested the HFO against other refrigerant options, including its existing standard and alternatives such as carbon dioxide.

He said the key was that even with “belt and braces” mitigation of the lower flammability aspect of the HFO, the system has been achieved at a significantly lower cost versus against the alternative F-gas compliant refrigeration systems trialed by Asda over the past decade.

He said: "Further energy savings have been achieved, verified through independent evaluation, and the maintenance requirements are very familiar for the existing service engineering base." The system reliability and safety performance are expected to mirror the retailer’s current 99.96% uptime.

One key aspect of HFO refrigeration systems is to mitigate for the risks of the A2L refrigerant. Asda has initially taken a conservative approach, Churchyard said: "As no design standard exists for commercial refrigeration using an A2L, we treated it as if it was A3 [‘flammable’, such as propane and other hydrocarbon refrigerants]."

But as the development of the system continued, Asda assembled what it describes as "a large compendium of technical detail and data, trial findings and next steps."

He said this data has proved vital: "Asda and its technical partners are now able to confidently assess where they can safely and viably align this standard to a 2L equivalent. It is important to stress that my objective isn’t working to an R45A standard, it’s a standard for A2Ls."

Churchyard said that the intention is to give the finished A2L standard to the Institute of Refrigeration for it to be disseminated as an industry guide for a best practice.

He said: “It is important to state that Asda is technology agnostic. This is a solution that works for our operational model now. We believe there is no single refrigerant product that offers a solution for everything.”

The retailer is also proclaiming success with another "disruptive" innovation: its Mistral-ducted display case system, which replaces refrigerant pipework with ductwork distributing cold air to the cases. The system promises to save significant time and money in maintenance.

Churchyard said: "For instance, the removal of sales floor condensate drains has eliminated a known hazard and almost all serviceable parts have been removed from the display case."

As it rolls out the system, it has achieved 50% savings in maintenance costs, Churchyard claims, along with 40% lower refrigerant gas charge and, most significantly, an 11% reduction in energy use.

He added: "Energy consumption is key to the retailer. Around 50% of our consumption is down to refrigeration — that is by quite a long way the biggest energy user."

A further element in Asda’s refrigeration strategy is demand side management — shutting down and restarting refrigeration systems when required, which both supports grid balancing and saves money. This initiative currently creates up to 20 MW of "virtual power," which can support up to 80,000 homes, Churchyard said. Asda’s aim is to double this in 2020.

As the F-Gas regulation continues with annual reductions in the "quota" of HFCs available to the market — and similar reductions start to be brought in globally under the Kigali amendments — and the drive continues towards lowering GWP of refrigerants, the cooling industry has been urged to focus on reducing the energy consumption of the system.

Consultant Ray Gluckman told the F-Gas Question Time audience: "It is vital to have a balance between energy consumption and direct emissions. There is no point in having systems with reduced GWP, if the energy goes up in the process."