As food retailers in the US face growing refrigerant regulations, the need for tools and resources that provide clarity on the cost of natural and low global warming potential (GWP) refrigerant technologies is becoming increasingly apparent. A new study comparing the upfront and ongoing costs of various natural and low-GWP refrigerant systems has provided a first-of-its-kind resource that could help build a pathway towards that clarity for retailers.
Authored by DC Engineering - an engineering design firm based in Meridian, Idaho – the study was commissioned by a national chain grocer and aimed to equip the grocer to make informed system selection decisions. The grocer chose to remain anonymous but agreed to make the study results public.
“This study is a great example of the kind of transparent and comprehensive cost comparison food retailers are looking for,” said Danielle Wright, executive director of NASRC. “As regulatory pressures increase, retailers need more tools like this to effectively compare their options.”
“With the ever-changing tapestry of refrigerant compliance issues, we have found end-users need clear, fact-based guidance on the most suitable system for their long-term operational success,” said Glenn Barrett, engineering manager at DC Engineering. “Both the first cost and lifecycle costs of different system designs are heavily impacted by the system options and features utilized. Providing a baseline of the client’s key parameters, and then adhering to those parameters, is imperative to achieving a meaningful comparison.”
The study compared both the upfront costs of installation and ongoing cost of energy for four different refrigeration system designs serving a 40,000 square foot market with a 900 MBH load. The baseline design was a 3-rack system using R-448A, which was compared to three other system designs:
A CO2 transcritical system utilizing a single rack and an adiabatic gas cooler
A micro-distributed system using R-448A and utilizing an adiabatic fluid cooler and a hydronic loop for heat rejection
A micro-macro-distributed system using R-290 for standardized cases and CO2 for specialty cases and utilizing an adiabatic fluid cooler and a hydronic loop for heat rejection
To obtain competitive installation pricing, the four system designs were bid across five regions using multiple contractors and OEMs. As a result, over 50 competitive bids were reviewed to analyze first costs. The bids were averaged to compare the variation of the case, equipment, and installation costs across each of the four system designs. Overall, the CO2 transcritical design resulted in the lowest first cost, even when compared to the baseline HFC system.
“It’s important to remember that this study reflects one retailer’s experience and is not necessarily representative of other retailers,” said Wright. “We’ve heard from a number of our retailer members that they are still experiencing significant cost premiums for CO2 transcritical systems.”
Energy performance was also modeled for each of the four system designs using a combination of Pack Calculation Pro, Excel, and other tools. Weather data was incorporated from each of the five regions and all system loads were kept constant for the purpose of comparison. The results reflected energy penalties in every region for all alternative system types, ranging from 9% to 122% above the HFC baseline system.
“It was very interesting to see how energy use differed between the various real world, commercially available, designs,” said Barrett. “It was particularly interesting – and encouraging – to see how the thermodynamic efficiency advantages of natural refrigerant solutions played out when compared to a very efficient HFC, multiple suction group, rack design using industry best practices. The study substantiated our view that natural refrigerant designs are both viable and varied to meet most any facility conditions but can indeed be improved to maximize energy efficiency.”
This study is an important first step towards providing retailers the tools they need to effectively compare their options. Looking ahead, NASRC plans to build on this study to incorporate additional system types and baseline assumptions, as well as energy performance data from the field.
“Our hope is that this study will serve as an important blueprint that can be expanded to include other system designs and field data,” said Wright. “NASRC’s goal is to help coordinate that expansion to drive more clarity for retailers.”
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