The transcritical CO2 system’s coolers outside the METRO wholesale store in Belgrade. (Source: METRO)
The transcritical CO2 system’s coolers outside the METRO wholesale store in Belgrade. (Source: METRO)

METRO Rolls Out First Transcritical CO2 Installation in Serbia

The international food wholesaler has other installations under construction in Moldova and Ukraine and recently completed a transcritical CO2 project in Austria.

Germany-based international food wholesaler METRO is continuing its rollout of transcritical CO2 (R744) refrigeration systems with its first installation in Serbia.

The retrofit project was completed in November 2023 at the chain’s Serbian flagship store in Belgrade, according to Olaf Schulze, Director of Energy Management and Real Estate Sustainability at METRO Properties, METRO’s real estate division.

The equipment was provided and installed by Carrier Commercial Refrigeration and provides 78kW (22.2TR) low-temperature (LT) and 454kW (129TR) medium-temperature (MT) capacity. Carrier also installed propane (R290)-based plug-in freezers with a cooling capacity of 28kW (8TR). (In December 2023, Carrier sold its commercial refrigeration business to Haier.)

This project, as well as the numerous other CO2 installations at METRO facilities worldwide, is part of METRO’s F-Gas Exit Program, initiated in 2013, which aims to phase out the use of HFCs and HCFCs in all of its stores by 2040.

METRO’s second transcritical CO2 installation in Serbia is planned for later this year at its second existing Belgrade location.

100% NatRefs

In Moldova, METRO is currently installing a transcritical CO2 refrigeration system at its third store. As there are only three METRO locations in the country, METRO Moldova will be the first arm of the company to use 100% natural refrigerants, explained Schulze.

Other transcritical CO2 projects currently underway include two in Ukraine at the chain’s locations in the Pozniaky neighborhood of Kyiv and in Lviv. These retrofit projects follow METRO Ukraine’s first transcritical CO2 installation in 2023 at its store in the Teremky neighborhood of Kyiv, which was delayed by one year due to the Russian invasion in March 2022.

The two current installations in Ukraine were described by Oleksandr Sikora, Head of Technical Operations at METRO Ukraine, at the ATMOsphere (ATMO) Europe Summit 2023 in September. The event was organized by ATMOsphere, publisher of

The new CO2 systems in Ukraine, supplied by Carrier, include ejector technology and heat recovery, as well as MT and LT remote cabinets. The systems’ capacities are around 450kW (128TR) for MT and 50kW (14TR) for LT, said Schulze. Some 75 propane (R290)-based chest freezers from AHT have also been supplied.

“The equipment was supplied weeks ago and will be fixed from local installers in the next month,” he added.

Eliminating fossil fuels

A transcritical CO2 refrigeration system was also installed at METRO’s 8,200m(88,264ft2) wholesale store in Salzburg, Austria, in November 2023. The system, including remote cabinets, was supplied by Carrier and provides a cooling capacity of 300kW (85TR) for MT and 50kW (14TR) for LT. Additional propane plug-in cabinets were provided by AHT.

During the retrofit project, two 55kW (15.6TR)-capacity heat pumps were installed to replace the store’s existing fossil fuel-based heating system. The heat pumps will use waste heat recovered from the CO2 refrigeration system for space heating in the store.

“The challenge was the refurbishment as it was the first time that we installed a heat pump in an existing wholesale store [to eliminate a] fossil [fuel-]heating system,” said Schulze.

To make the building, constructed in the 1980s, suitable for a heat pump, the building envelope was renovated to improve efficiency, and low-temperature heating surfaces such as ceiling radiators and air heaters were installed.

“The challenge was the refurbishment as it was the first time that we installed a heat pump in an existing wholesale store [to eliminate a] fossil [fuel-]heating system.”

Olaf Schulze, METRO Properties

Due to a lack of “commercially attractive alternatives” available at the time of planning, the heat pump installed at the Salzburg store uses f-gas R454B, he added. R454B is an HFO/HFC blend consisting of 31.1% R1234yf and 68.9% R32; it has a 100-year GWP of 466.

METRO’s adoption of heat pump technologies is part of its Heat Exit Program, which began in 2021. The wholesaler’s next heat pump installations will be at two new stores in Germany and its existing store in the Jankomir neighborhood in Zagreb, Croatia.

According to Schulze, the company has yet to decide what type of heat pumps it will install at the three locations, but the preference is natural refrigerant-based.

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