Those who can remember when depletion of the ozone layer by CFC refrigerants forced the US food retailing and other industries that require refrigeration to phase them out in the 1990s are likely experiencing déjà vu as food retailing and other industries make yet another transition to a whole new generation of refrigerants that are kinder to the environment.
In the 1990s it was HFC refrigerants that replaced CFC refrigerants, and in the decades after their introduction, HFCs became the world’s most widely used refrigerants. But even as their use became more common, we started to learn that while HFCs may not be ozone-depleting, their high global warming potential (“GWP”) means they are damaging the environment in a different way, that is, by contributing to climate change.
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This has led to the development of an entirely new class of refrigerants, HFOs — short for hydrofluoroolefins — as lower-GWP alternative refrigerants. At the same time, the food retailing industry and other big users of refrigeration are entertaining a return to some older refrigerants that fell out of favor in the past, such as ammonia (“NH3”), carbon dioxide (“CO2”), and propane (“R290”). These refrigerants are being rebranded as “natural refrigerants” and touted as the best replacements for the HFC refrigerants we have all been using but nearly everyone now agrees must go.
But are natural refrigerants or are HFOs the next generation of refrigerants for supermarkets? Before we take on this big question, let’s take a step back and define Global Warming Potential for those of us who need a little refresher.
What is the GWP of refrigerants?
Greenhouse gases warm the earth by trapping energy so that it can’t escape the atmosphere, acting almost as a blanket over the earth. CO2 is a greenhouse gas, a very common one produced by both natural processes, such as the decomposition of dead trees, and human activities, such as the extraction and use of fuels like coal, oil, and natural gas.
Global Warming Potential, or GWP, is a measure of how much heat is absorbed (trapped) by specific greenhouse gases in the atmosphere. GWP numbers indicate how much energy will be absorbed by 1 ton of a gas (such as refrigerants, hydrocarbon combustion products, methane from the digestive systems of cows, and many others) over a certain period of time, usually 100 years, compared to the heat absorbed by 1 ton of CO2 (the reference gas).
A gas can be low-GWP because it traps less heat or because it breaks down quickly once released into the atmosphere and so has a short lifetime. As refrigerants are the gas of interest here, the higher the GWP of a refrigerant, the greater the warming effect will be on the earth compared to C02. This is why low-GWP refrigerants are more environmentally friendly and why businesses that use refrigeration are being required to adopt new lower-GWP refrigerants.
The Transition to HFOs in Grocery Stores
New international agreements and state and national laws regulating the release of harmful greenhouse gases, including refrigerants, have been proliferating over the past two decades and started a slow but now accelerating phase-out of high-GWP refrigerants. The American Innovation and Manufacturing (AIM) Act of 2020 included provisions that allow the EPA to phase down and then phase out the use of high-GWP HFCs even faster.
In the US, new refrigeration systems that use high-GWP HFCs (such as R404A, the most common refrigerant in use today in the US food retailing industry) can no longer be manufactured or installed. And in California, as of January 2025, certain HFCs will no longer be able to be sold at all. Even elsewhere, national regulations and international agreements restricting the manufacture of new high-GWP refrigerants are reducing their availability and increasing their cost, which will result in the nearly complete elimination of R-404A, R-407A&C, and other common refrigerants over the next 15 to 20 years.
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Where does this leave grocery stores? We spoke with Steve Moss, Head of Refrigeration at City Facilities Management, to learn more about the current state of supermarket refrigerants and how grocers are navigating the transition to low-GWP refrigerants. “HFCs are on the hit list,” Steve says. “This means their days are numbered, and their number will be up before we know it.”
Steve expects to see a faster transition from HFCs than the transition we saw in the nineties from ozone-depleting CFCs after the Montreal Protocol called for their eradication. “We’re in a fast-tracked phase-down,” he says. “It’s not going to take 15 years for HFCs to phase out.”
“In existing refrigeration systems across the U.S., CFCs like R-22 and HFCs like R-404A and 407A are being replaced with HFOs and HFO blends,” Steve explains. HFO blends are essentially a mix of a lot of HFO with some HFC refrigerant. With zero ODP (ozone depleting potential) as well as low GWP, HFOs are considered to be the current best environmentally friendly replacement for HFCs and HCFCs in existing refrigeration systems. The most commonly used HFOs in supermarkets include R-448A, R-449A, and R-513A. To give an idea of how they compare in GWP, R-404A has a GWP of 3943, whereas R-448 has a GWP of 1,273 (67% lower) and 513A (an HFO blend replacement for R134a, not R404A) a GWP of 572.
HFO Refrigerant Considerations
The big question seems to be … what then? What environmentally friendly refrigerants will supermarkets be using in the coming decades? Natural refrigerants are super low-GWP but are also naturally flammable or naturally toxic, and/or naturally difficult to utilize safely in refrigeration systems. This is why they fell out of favor for commercial refrigeration system use many decades ago and were displaced by synthetic refrigerants such as CFCs and then HFCs.
The new HFO refrigerants approach the GWPs of some natural refrigerants — and in some instances boast even lower GWPs. But to do so, they take on some of the negative characteristics of natural refrigerants that caused them to fall out of use in the first place.
One such downside for some HFOs is their flammability. Steve explains, “While it takes a lot more energy to ignite HFO gasses compared to propane, one of the natural refrigerants being promoted today, their mild flammability has slowed their adoption, as they have not yet been fully approved in building code regulations in most states.”
The GWP of HFO blends declines to even lower values as the amount of HFCs in the blend is lowered. However, there are drawbacks — the very low-GWP HFOs have some of the same shortcomings as the natural refrigerants — again, flammability, toxicity, and increased refrigeration system cost or complexity. Take R-1234yF, sold under the brand name Option YF and SOLSTICE-yf, as an example.R-1234yF has a GWP of only 4 but contains small amounts of carbon tetrachloride, which is a potential carcinogen.
Still, HFO refrigerants can be a much more practical alternative than switching to CO2 and other ultra-low-GWP natural refrigerants, which require a total refrigeration system architecture change — that is, brand new refrigeration compressor systems, piping, refrigerated display cases, and other refrigeration system elements, machinery. This makes CO2, propane, and ammonia options mostly for new builds and is resulting in resistance to and poor adoption of these refrigerants for existing refrigeration systems. This is the case even during remodels, when the goal for most food retailers is to improve their store sales appearance and offerings as much as possible — not to spend most of their capital replacing their entire existing refrigeration systems, all or much of which may have many years of remaining service life.
But Steve says all eyes are on California at the moment. “According to history, California usually serves as the blueprint for the rest of the country. It’s likely many states will follow what they do.” The magic GWP number in California and the US appears to be a GWP of less than 150, which delivers a 97 percent reduction in GWP. There are several HFOs that achieve this GWP with very low flammability levels, no toxicity, and the ability to be used as a replacement refrigerant in existing systems as either near drop-in or partial drop-in replacements. Some examples include R-455A, R-454C, and R-516A.
For the Near Term: R-448A Refrigerant Retrofits for Food Retail Store Refrigeration Systems
In the meantime, higher-GWP HFO/HFC blends like R-448A are the low-GWP refrigerant gas of choice for existing refrigeration systems, requiring only a simple drop-in gas change retrofit which most of the commercial refrigeration service and contracting industry is able to complete easily.
As of 2020, the HCFC R-22 is no longer produced or imported. Since that time, only recovered, recycled, and reclaimed supplies have been available. As a result, supermarkets are aggressively retrofitting away from R-22 and R404A as their availability is shrinking rapidly. At the moment, most retrofits from the above are to R-448A and R-449A, which are near drop-in retrofits. Steve has overseen such retrofit projects for dozens of supermarkets.
The benefits of a refrigerant retrofit, Steve says, are manifold. “Not only are you switching to a low-GWP gas which will be better for the environment, but you’ll also see a return on your investment due to increased energy efficiency.”
He explains, “The replacement HFO refrigerants themselves are more efficient, but also as part of the retrofit process, you’re touching every case and making sure it’s running correctly. While it’s not technically a total recommissioning, it’s like a recommissioning in that you’re going to perform a lot of corrective tasks along the way. He estimates an improvement in refrigeration system energy efficiency of up to 17 percent for stores transitioning from R-404A to R-448A or R-449A. “And of course, with equipment operating optimally, you’re going to have happier customers.
At least for now, until we have a clear path forward, Steve recommends an R-448A refrigerant retrofit for all grocery stores that still use HCFCs and HFCs. “At the very least, we know we’re doing less harm to the environment,” Steve says. “And while there may be an initial investment upfront, the cost savings in terms of improved energy efficiency will make it worthwhile.”
And while there may be an initial investment upfront, the cost savings in terms of improved energy efficiency will make it worthwhile.Steve Moss, Head of Refrigeration
The Future of Supermarket Refrigerants
While we can’t tell you exactly what the future holds for refrigerants, manufacturers are working every day to produce new refrigerant gases with the lowest possible GWP ratings. This fact coupled with new legislation coming out all the time can make it hard for FM leaders to keep up. This makes it critical to partner with a provider that’s on the leading edge of sustainable FM solutions.
At City, we offer a comprehensive approach to sustainability, which has been proven to reduce retail clients’ GHG emissions dramatically as well as reducing energy consumption by as much as 25 percent. Our 360-degree carbon management approach is aligned with the Net Zero framework developed by the Science-Based Targets Initiative (SBTi) to prevent refrigerant leaks and reduce energy. Learn more about our sustainability services.
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