French refrigeration manufacturer CTA Group has found that reversible propane (R290)-based heat pumps – produced by Italian OEM Euroklimat – can cut a Carrefour supermarket’s HVAC energy consumption by around 10% compared to HFC alternatives.

Thanks to lower GWP, lower refrigerant charge and higher system efficiency, the air-to-water Hera heat pump was also found to significantly reduce greenhouse gas emissions, according to Manuel Fernandes, R290 Technical Expert at CTA Group.

Fernandes delivered CTA’s findings during his presentation in a HVAC and heat pumps session at the ATMOsphere (ATMO) Europe Summit on natural refrigerants. The conference took place November 15–16 in Brussels and was organized by ATMOsphere, publisher of

Need for ‘sustainable solutions’

The data shared by Fernandes were based on a 1,600m2 (17,200ft2) Carrefour Mestdagh supermarket in Charleroi, Belgium, that opened two years ago.

While Carrefour Mestdagh historically has used either an R404a-based direct expansion system or an R32-based chiller or heat pump for its HVAC, the retail chain wanted to install a system that used a low-GWP refrigerant following its 2020 commitment to use “sustainable solutions” in its new stores, explained Fernandes.

After assessing different options, the store opted for a plug-and-play propane heat pump for its HVAC, partially due to its environmental benefits, but also for economic reasons.

“For Mestdagh, going to a sustainable solution must also be aligned with a low financial capital and operational expenditure,” he said.

While the supermarket uses CO2 (R744) for its refrigeration system, its HVAC requirements meant that heat recovery was not a viable option, he added.

Higher yield and ROI

In addition to the rooftop heat pump – which provides 135.9kW (38.6TR) in heating capacity with a seasonal COP of 4.43 – the system consists of 11 HVAC cassette units and a 2,000L (528gal) buffer tank. It is separated into two circuits; one serving the store’s heaters and the other for “social premises” within the building.

For heating, it can supply water temperatures of 30–60°C (86–140°F) in ambient temperatures down to -20°C (-4°F). For cooling, it can produce water temperatures of -15–15°C (5–15°F) in ambient temperatures up to 45°C (113°F), making it suitable for all European climates, said Fernandes.

In addition to thermal comfort and hot water production, the unit can also be used as part of the refrigeration system’s CO2 condensation loop.

With an average energy input of 30.7kW, the Hera heat pump costs around €55,700 (US$58,800) a year to run, compared to €65,100 (US$68,700) for an R32-based chiller unit of similar capacity.

Because of higher yield and ROI, as well as the significantly smaller environmental footprint, Carrefour Mestdagh is committed to using a similar approach in future stores.

“Whether from an ecological or economical point of view, Mestdagh has realized that the alternative CO2-propane solution is vital to equip all of our future stores,” said Arnaud Bourlard, Technical and Infrastructure Manager at Mestdagh. “It is an approach we hold dear for a cleaner future.”

“Whether from an ecological or economical point of view, Mestdagh has realized that the alternative CO2-propane solution is vital to equip all of our future stores.”

Arnaud Bourlard, Mestdagh

Range of applications

CTA Group has worked with R290 for over 15 years, having sold its first propane unit in Switzerland in 2006.

Now, with more than 2,500 R290-based units installed, propane makes up 72% of the manufacturer’s production and CTA Group aims to offer 100% “natural cooling” by the end of 2025, according to Fernandes.

With R290 products that range from 1kW to 1MW (0.3 to 284TR) that can supply temperatures from -25°C (-13°F) to 60°C, this natural refrigerant is suitable for a range of systems and applications, he added.