Advansor and Coop Say CO₂ Systems Performed Well in Europe’s Heat Waves

The chemical industry for decades produced f-gas refrigerants (CFCs, HCFCs and HFCs) with very high GWPs – hundreds if not thousands of times that of CO₂ (R744)’s GWP of one – thereby contributing to the crisis of global warming that led to heat waves across Europe and other regions this summer.

This has led to the adoption of natural refrigerants, with near-zero GWPs, in many applications, especially transcritical CO₂ refrigeration systems in supermarkets. In Europe, 108,000 food retail stores employ either transcritical CO₂ racks or condensing units, a market penetration of 34%, according to ATMOsphere’s 2025 Market Report.

Now, in an ironic twist, these CO₂ systems are being scrutinized by a major f-gas producer for their performance in supermarkets during the particularly intense heat waves that blanketed Europe this summer, caused in part by the long use of f-gas refrigerants.

“When outdoor temperatures exceed historical design assumptions, CO₂ systems can become particularly vulnerable: extreme heat drives system pressures higher, reduces efficiency, and increases the likelihood of temperature excursions, mechanical strain, or emergency shutdowns,” wrote Chemours in a sponsored article published in July in European Supermarket Magazine (ESM).

It is true that many European supermarket operators in France and other countries reported refrigeration problems (typically without specifying the refrigerant) this summer as ambient temperatures exceeded 40°C (104°F). It is also true that transcritical CO₂ booster systems generate supercritical CO₂ at high ambient temperatures that exceed the molecule’s critical point, potentially reducing efficiency.

However, recent generations of transcritical CO₂ systems have been equipped with efficiency-enhancing technologies, such as 130bar pressure rating, parallel compressors, ejectors, adiabatic gas coolers, subcooling and other technical innovations that have enabled efficient operation in warm weather and helped boost adoption of CO₂ systems in Spain, Italy and other countries subject to high summer temperatures.

While information on the performance of CO₂ systems in Europe this summer is not generally available, interviews with a major supplier of CO₂ refrigeration, Advansor, and a large Italian supermarket chain, Coop, reveal that their CO₂ systems have performed well in spite of very high temperatures.

Climate-relevant technology

According to Advansor’s 2025 ESG report, the Danish OEM, which is a division of U.S.-based Dover Food Retail, has manufactured over 20,000 transcritical CO₂ systems, and they have been installed in 18 of Europe’s top 20 retailers.

Many of these retailers operate in countries that experienced heat waves in 2026, including Italy, France, the U.K., Germany, France and Greece. Yet Advansor’s transcritical CO₂ systems “did not experience any problems or breakdowns,” because of the summer heat waves, said Anders Mønsted, Business Development Manager, Industrial Refrigeration. “We believe it is due to how the system is designed and built. Advansor designs the systems to the climate conditions they will be operating in and are using the technology that is relevant in these climate conditions.”

Among its key design features, he said, Advansor systems employ 130bar maximum pressure as standard; gas coolers that accommodate high ambient temperatures, so that the CO₂ gas is cooled as close to the ambient temperature as possible; and parallel compressors, ejectors and ultra-low superheat equipment.

These features make a measurable difference. The 130bar design increases system capacity by 13% and COP by 7% compared to 120bar for temperatures up to 45°C (113°F), according to Advansor. A Danfoss study of French supermarkets determined that ejectors reduce the energy consumption of a basic CO₂ booster system by 35%.

“Advansor designs the systems to the climate conditions they will be operating in and are using the technology that is relevant in these climate conditions.”

Anders Mønsted, Advansor

Reducing superheat in the evaporator, Mønsted explained, increases the percentage of the evaporator dedicated to evaporation, increasing evaporator temperature and “getting you closer to the temperature you want in your cabinet.” To prevent any liquid from entering the compressor, Advansor adds a liquid separator and an additional heat exchanger for superheating.

Some systems need to be more robust, depending on the location. For example, a system in Spain, designed for a maximum of 42°C (108°F) with more compressors and bigger gas coolers, may be 15–20% more expensive than one in Northern Germany, designed for a maximum of 36°C (97°F), Mønsted noted. The payback for the additional cost of a well-fortified CO₂ system is one to two years, based on electricity cost savings that can be as much as €100,000 ($116,300) annually for a large store, he said.

While Advansor will include an adiabatic gas cooler in its design if it is specified, its CO₂ systems do not typically employ one as it uses water to reduce gas cooler temperatures at high ambient temperatures. “Lack of water resources is a big issue in the countries that experience heat waves and operating systems with dry gas coolers saves water,” said Mønsted.

Mønsted acknowledged that basic CO₂ systems that are not designed for extremely high ambient temperatures may be subject to operational challenges. “When you design CO₂ systems, you can cut a lot of corners; for example, you can save a lot of money on your gas cooler on the copper piping, increasing the pressure drop and delta Ts,” he said. “But then on a very warm day you cannot deliver what you were supposed to deliver.”

There are also practices that affect all refrigeration systems in hot weather such as having a dirty gas cooler or condenser, he noted.

More than 200 stores with CO₂

Coop, a chain of about 1,000 supermarkets in Italy, employs transcritical CO₂ systems from Advansor (distributed by De Rigo) as well as from Arneg, Carrier and Epta. The retailer began using transcritical CO₂ in 2013, made it the standard in 2017, and as of December 2025 was employing it at 207 stores, said Ruggero Alamanni, Food Refrigeration Systems Specialist for Florence, Italy-based INRES Coop, the engineering planning group for Coop.

Coop’s CO₂ systems “performed very well” despite the high temperatures, which reached 40°C in Northern Italy, said Alamanni. “During this heat wave, we have not experienced any technology-related issue.”

“There were some issues in the early years,” he added, “but over the last five years we have not had a problem” as long as basic maintenance, like cleaning the gas cooler, is done.

Coop chose CO₂ refrigerant because “the environment is a very important issue for us,” said Alamanni. In addition, alternatives like A2L gases are an uncertain bet. “We don’t know if we put this type in now, in 10 years, will it be OK or not? Who knows? If we choose CO₂, it’s natural; we know the future is stable.”

The key to managing CO₂ refrigeration in heat waves is proper design, especially the gas cooler, Alamanni noted, adding that Coop’s are rated for 130bar maximum pressure, supporting optimal pressure. Another key factor is parallel compression, used in many Coop stores since 2016. In addition, its Epta CO₂ systems employ its ETE (extreme temperature efficiency) feature, while some outlets with Carrier CO₂ systems have begun using ejectors. Coop prefers not to use adiabatic gas coolers as energy-enhancing systems.

CO₂ systems use more energy in very high ambient temperatures, but energy use rises for f-gas systems in the summer as well, said Alamanni. And in the winter, CO₂ systems consume less energy so that overall, compared to traditional f-gas systems, “we think we have more or less the same energy cost.” In terms of the cost of refrigerant, f-gases are much more than CO₂, he noted.

Alamanni declined to compare the different types of CO₂ systems and energy-efficiency technologies. “It’s very difficult to compare different stores in different places with different temperatures,” he said.

“During this heat wave, we have not experienced any technology-related issue.”

Ruggero Alamanni, INRES Coop