German retail giant Metro recently replaced an inefficient, 20-year-old R404A refrigeration system at an outlet in Ruse, Bulgaria, with a transcritical CO2 system equipped with ejectors – with zero downtime at the store.

This was done in a move towards natural refrigerants and to save electricity, explained Olaf Schulze, Director Energy Management at Metro AG. “It is our mission and long-term strategy to ensure sustainability from farm to fork for customers and for our own operations,” said Schulze. The transcritical CO2 system is Metro AG’s 18th  with ejectors.

Metro’s 7,000m2 (75,347ft2) Ruse store opened in 1999 and was due for an upgrade this year to improve its overall efficiency. In only four months (from May until end August), the entire refrigeration system was replaced, and various other improvements were made, including the addition of glass doors to fridges to minimize openings and thus save energy.

The new system will realize a projected electricity saving of a minimum 20% for cooling and more than 35% on heating, explained Schulze. It also solved the problem the store had with HFC leakages.

“Our stores can never and will never stop. It was like operating on an open heart.”

Olaf Schulze, Metro

The biggest challenge for this project was that the entire retrofit had to be done without any downtime to the store. “Our stores can never and will never stop,” explained Schulze. “It was like operating on an open heart.” But the installation team, Carrier BG, with the support of Frigo Consulting, pulled it off and commissioning of the new store was completed in September.

This is one of Metro’s 11 wholesale stores in Bulgaria, the second to be equipped with a transcritical CO2 ejector system (the other being its Sofia headquarters store completed in 2018). Three of its other stores have subcritical CO2 installations.

For more on this project, check out the Nov/Dec issue of Accelerate Magazine, available at on November 19.

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