With its “first ever” CO2 (R744) integrated HVAC&R system installed in a La Chorrera, Panama, supermarket, Italian OEM Arneg has observed a 12% energy savings over a similar store functioning with independent CO2 refrigeration and a packaged air-conditioning system.

Details about the design and operation of the integrated system were presented by Rolando Bissot, Engineering and Maintenance Manager at Arneg Central America, at the 2023 ATMOsphere LATAM, held in Mexico City, November 8‒9. The event was hosted by ATMOsphere, publisher of R744.com.

Bissot used 12 months of operational data with the AC, which was used solely for moisture control, in determining the 12% energy savings.

“We wanted to take advantage of the heat recovery capacity from the CO2 system to control the humidity,” he noted. “We knew it would work theoretically, but seeing it in real life brought satisfaction.”

Connecting the systems provides the “freedom to monitor the energy consumption and control the equipment,” Bissot said. “You can draw air-conditioning to decrease the freezing while deciding when to turn it off and on, based on operational hours.”

The company has installed approximately 68 transcritical CO2 systems in Central America in the last eight years. “We know about the savings of these kinds of technologies,” Bissot said. “We can take the operation figures and calculate the actual return on investment (ROI) for future installations.”

Integrating the AC with the refrigeration at the 960m2 (10,333ft2) Panama store increased the overall cost by US$26,000 (€24,000). “However, the energy savings in the first year were greater than that amount, making the ROI less than a year,” Bissot said. “The customer can see that the new store with integrated air-conditioning consumes less [energy] than stores just 2km (1.2mi) away, with one store consuming almost 25% more.”

The refrigeration part of the integrated system used transcritical CO2 with parallel compression, heat recovery and an integrated chiller to provide 60kW (17.1TR) of medium-temperature and 15kW (4.3TR) of low-temperature capacity. The 150kW (42.7TR) capacity HVAC system operates with chilled water from the CO2 rack and reheats the hot water from the refrigeration.

“This technology, unifying all the circuits and systems in one piece of equipment, has been applied in European convenience stores the past two years,” Bissot noted.

Last March, in one CO2 skid, Arneg Canada provided a 13-story mixed-use building in Montreal, Quebec (Canada), with supermarket refrigeration and building HVAC. “We’ve heard a lot of people in the industry say that HVAC CO2 doesn’t exist, but we are doing it,” said Phillip Walker, Director of Refrigeration Solutions at Arneg Canada, in a presentation at 2023 ATMO America.

No regrets with CO2

Once a customer installs a transcritical CO2 system, they never ask to go back to synthetics, Bissot noted. “This is happening because they alleviate fears, see energy savings and become believers in this new technology.”

“This kind of system does not have an expiration date,” he added. “We do not have to change it in 20 years or look for a new refrigerant.” 

Additionally, he reports initial costs for CO2 systems are going down. “With more manufacturers, the cost of [CO2 system] components and materials is becoming more competitive every day compared to conventional systems,” Bissot said. “The ROI becomes shorter than in the past.”

Bissot noted fear of the higher pressures with CO2 refrigeration may hold some Latin American clients back, especially since the region tends to look to the U.S. for guidance. “However, these technologies have been in Europe for 20 years, so we need to turn our heads there.”

He compared it to a pressurized cylinder under the seat of a forklift. “The person sitting there is not fearful because it is designed for such purposes; it’s the same in CO2 refrigeration,” he said, adding that training familiarizes the technology and diminishes concerns.

“We took on the task of training client staff and contractors to address concerns about the new technologies,” which includes Arneg assisting local contractors with their first installation, Bissot said.

Expanding technology

CO2 refrigerant technologies are getting both bigger and smaller. “We are installing CO2 systems in larger facilities like distribution centers, but [also] making smaller condensing units for convenient stores,” Bissot said. “It’s an enormous market, and we’ve found many solutions to integrate into future projects.”

“We believe in this technology for the Latin American market,” he said, having been personally involved in the first implementations of CO2 refrigeration solutions in Central America.

With Europe already implementing mixed systems using CO2 and ammonia (R717)/glycol for temperature control or low-temperature subcritical CO2, “these technologies will become more common in Latin America,” he noted, especially as customers seek to become green and reduce their CO2e emissions and energy consumption. “New [users] will adopt these technologies; we will see it growing.”

Headquartered in Venice, Italy, Arneg operates 21 manufacturing facilities worldwide. The company has approximately 74 transcritical CO2 booster systems and 43 low-temperature subcritical CO2 systems in the Americas.


In addition to R744 equipment, Arneg manufactures propane (R290) equipment and ammonia, ammonia/glycol and ammonia/CO2 systems.