Transcritical CO2 refrigeration systems have been steadily gaining traction in North American supermarkets, particularly in Canada. For retailers seeking to use a low-GWP, energy-efficient refrigerant and to future-proof their system against regulations on synthetic refrigerants, transcritical units are seen as an increasingly viable option.

For retrofits, however, transcritical systems have typically been seen as a less attractive option – primarily due to the work and costs associated with refashioning an existing store to support the high pressures of CO2. But Sobeys, Canada’s second largest retailer — and the largest retail user of transcritical refrigeration in North America — is rewriting the retrofit script for transcritical systems.

Transcritical refrigeration is Sobeys’ standard system. As of September 2015, 78 Sobeys stores across eight Canadian provinces – in addition to 63 in Quebec operating under the IGA banner – were using CO2 transcritical booster systems with heat reclaim. Each year, another 15 to 20 stores both new and renovated are equipped with the systems. Some of these stores are franchise operations. spoke to Rod Petersen about a recent Sobeys retrofit in Ontario. Where in Ontario is the retrofit?

Rod Petersen: Our next retrofit in Ontario will take place in a Sobeys banner new-build in Oakville. What refrigerant did the original system use?

Petersen: The original system was R507. Why did Sobeys decide to go for CO2 transcritical over a CO2 cascade or HFO blend system?

Petersen: In 2013, transcritical refrigeration became Sobeys’ national standard in new builds. The transcritical system is the only system that met our environmental objectives and made economic sense. How much did the retrofit cost? How does the cost compare to retrofitting in order to produce a cascade or other type of system?

Petersen: We are retrofitting transcritical CO2 systems into older stores that require a 100% replacement of the existing refrigeration: new cases, racks and piping.

As the complete refrigeration system is being replaced, there is no additional cost to do CO2. Based on experience, Sobeys believes the initial cost of a transcritical system, including all components (racks, cases, controls, etc.) is comparable to that of traditional DX systems and lower than others using synthetic refrigerants with the same level of controls. We also believe transcritical is more efficient than traditional DX with synthetics. What will be the baseline for monitoring the performance of the system?

Petersen: The baseline will be the existing baseline data from the same store prior to the renovation. Is Sobeys looking to retrofit more stores to CO2 transcritical in the future?

Petersen: Yes – Halifax, Nova Scotia in 2016. Why did Sobeys choose not to use plug-in cases?

Petersen: Plug-in cases have considerably higher maintenance and operating costs, making the cost of implementation prohibitive. Also, design considerations and overall HVAC and control systems do not permit the use of plug-in cases. They do not provide a total solution. Because of the specialty nature of our product offer and specialty case requirements, compressors, grills and condensers cannot be incorporated into these cases.

For an in-depth look at how to retrofit ageing HFC systems with transcritical CO2, please click here.

Author r744