All retailers grapple with the energy and environmental costs associated with running their stores, but only retailers that sell perishable food deal with the added burden of refrigeration, which can account for more than 40% of their electric bill.
Thus, reining in the energy consumed by their commercial refrigeration systems was the first topic of the day at the third annual Refrigeration Roundtable, held Sept. 20-21 at the Schaumburg Convention Center, Schaumburg, Ill. Hosted by SN and ContractingBusiness.com, a sister publication at Penton Media, the roundtable brought together refrigeration executives from food retailers and the contracting firms that install and service commercial refrigeration. The event was sponsored by Hill Phoenix, Danfoss and Emerson Climate Technologies.
Participating in the roundtable from the supermarket industry were Jon Scanlan, director-refrigeration and energy management, Hy-Vee, West Des Moines, Iowa; Paul Anderson, group manager, refrigeration/engineering, Target Corp., Minneapolis; Joe Gallego, manager of refrigeration and HVAC services, BJ’s Wholesale Club, Westborough Mass.; Howard Hehrer, senior engineer, Meijer, Grand Rapids, Mich.; and Ted Alwine, director, engineering, Martin’s Super Markets, South Bend, Ind.
Read more: Transcript of Refrigeration Roundtable
Representing the contracting industry were Mike Martin, president, Carlson & Stewart, Marshall, Minn.; Bob Axelrod, president, Cooling Equipment Service, Elk Grove Village, Ill.; Steve Tibbets, owner, T&O Refrigeration, Fayetteville, Ga.; Jai Hoover, vice president Remco, Allentown, Pa.; Brent Beishuizen, service manager, Zone Mechanical, Chicago; and Ed Mattos, president, Remco. Also participating in the energy discussion was Scott Martin, director of sustainable technologies, Hill Phoenix, Conyers, Ga.
The roundtable participants shared a wide range of energy-saving strategies, such as Hy-Vee’s effort to optimize its systems by using utility benchmarking provided by Ecova, Spokane, Wash. “We identify outlier [stores]” — a top 20 list — “that use the most energy and try and go back and attack it,” Scanlan said. “We work through the contractors and our store directors to try and improve.”
Stores become energy outliers for any number of reasons, said Scanlan. “We all know that the techs can be under a lot of pressure at time of repair, and set points can get changed,” he said. “There are plenty of opportunities for suction pressure to get adjusted and it doesn’t get put back, or defrost times are changed to combat a particular problem and never changed back.”
Some stores may lag because their frozen food cases haven’t yet taken advantage of LED lighting upgrades from fluorescent lighting.
In addition to using LED case lighting, Hy-Vee, like many food retailers, is putting doors on medium-temperature cases, installing EC (electronically commutated) fan motors in cases, and “trying to build as many efficiencies into the system as possible,” said Scanlan.
As a small chain with only 21 stores, Martin’s Super Markets has limited resources to expend on refrigeration technology, acknowledged Alwine. “We have mostly stayed with central DX systems. That seems to be what makes sense for us, that’s what we’re familiar with. Maybe it’s because we still feel that it’s a very efficient system.” The sluggish economy has also made it difficult for him to “spend big bucks on new things and take chances.”
These limitations have also prompted Alwine to focus on improving new and existing systems to make them as efficient as possible. For example, in newer stores Martin’s has worked hard on optimizing ambient sub-cooling, a low-cost process. “And by watching that process and maintaining proper head pressures and allowing that to work for you with cold weather ambient, we found that we can realize substantial energy savings by reducing compressor run-times,” he said.
At BJ’s Wholesale Club, the fastest-growing part of its business is perishable-food retail, which grows every quarter, posing energy challenges, said Gallego. “When we remodel, we’re adding racks, we’re adding new systems whenever possible and we also have merchandising vendors installing self-contained cases, adding to overall energy use,” he said.
One huge challenge the 200-club chain is starting to consider is its building envelope. “Typically, our older clubs were designed as a ‘vanilla box’ and nobody considered RH [relative humidity] or more importantly, dew point,” he said. “We have really been addressing that issue over the past two years with great success and I see many other chains now starting to look at dehumidification systems and controlling building envelopes, which makes a big difference in the efficiency of the systems.”
Gallego identified “low-hanging fruit” for energy reduction, such as suction pressures. “If we can get those suction pressures up and have less run time in the compressors, energy usage is down,” he said. Gallego also pointed out the advantages of floating suction pressure, what he called “an easy energy saver.” But this requires that technicians verify that transducers are reading correctly.
In addition, in the last two or three years BJ’s has gone through many clubs and replaced every case to take advantage of more efficient coils, producing energy savings that “can be tremendous.” With the efficiencies of the new clubs and lighting systems, “our energy usage has gone up less than 2%, which I don’t think is too bad considering the addition of five new buildings,” he said.
For Target, saving energy is about understanding all of the interactions within refrigeration systems, including the system, its components, training, contractors and manufacturers, said Anderson. But perhaps most important is “understanding the application you’re designing for,” taking into account the store’s format and size and the intended use of the equipment,” he noted. “If you can truly understand those initial design considerations and consider how the design will impact your total cost of ownership, that will go a long way in helping you achieve your goals and drive some really good results.”
Target has specific goals for energy — encompassing carbon impact, as well as the Environmental Protection Agency’s Energy Star Program — which are outlined on its corporate website (https://corporate.target.com/corporate-responsibility/environment/efficient-operations). These are two areas where “we measure ourselves according to these goals, and that’s open for the public to view.”
Target’s design considerations account for the needs of store merchandisers, Anderson said. For example, in selecting refrigerated cases, Target considers shopability — making sure that customers can buy the product that they want. “We work very closely with our merchants to develop and implement a solution that fits their needs,” he said.
Beyond the design and the manufacturing of refrigeration components, the contractor’s installation, start-up and operation of those components are also critical to energy conservation, observed Anderson. “So you have to have strong ties with your contractors,” he said. “You have to help each other understand what the needs and wants are and where there may be gaps between Target’s performance and the contractor’s performance, and work to close those gaps.”
Target has looked at a number of refrigeration compressors and refrigerants over the last few years, with energy considerations in mind. “There’s been a large focus in the industry about the best refrigerant, and how to get the best performance out of that refrigerant,” he said. “We’ve looked at some refrigerants that haven’t really been applied in supermarkets in the past, like R-134A.” Selecting the right refrigerant for an application, along with an optimized system or component, “will help you deliver the results you’re looking for.”
For example, Target has found that R-22 replacements such as R-407A, applied to existing R-22 systems, don’t cause a change in energy efficiency. R-134A, applied with optimized compressor technologies, does manifest energy efficiency gains, said Anderson.
Target has also begun testing a few alternate refrigerants such as carbon dioxide and found that CO2 systems experience an increase in energy consumption across the board, some more than others. Secondary (pumped) CO2 systems, for example, yield about a 24% increase in energy use, Anderson said, while for cascade CO2 systems, it’s about a 10% increase. The company has also looked at glycol as a secondary refrigerant and observed about an 18% increase in energy consumption.
According to Hill Phoenix’s Martin, other retailers do see energy parity with CO2 pumped and cascade systems compared with conventional systems. In Target’s case, which was not as favorable energy-wise for those systems, “some of that is our fault, as we had some misapplications in design and lack of component availability in the appropriate capacity range,” he said. These issues “hopefully have been corrected in stores going forward, we’ll soon see.”
The Case for Cases
Though they may face resistance from their store merchandisers, many retailers are installing glass doors on refrigerated cases to save energy. “We began using doors in medium temp cases in 2011 for new installations and to date we’ve had great results,” said Scanlan.
Target has been evaluating the performance of doors on medium-temperature cases in five stores for more than a year. “We have some really good data and at this time we’re reviewing the data to ensure that we make good decisions going forward,” said Anderson.
Read more: Transcript of Refrigeration Roundtable
Anderson said he was not prepared to dispel the notion held by many merchandisers that sales drop as a result of installing doors on cases. “I think it’s important for everyone to take a very close look at the numbers and all the performance factors when you apply new technologies,” he said. He also advocates working closely “not only with your designer in-house and your manufacturing base, but also with the contractor before you apply those technologies to ensure that you’ve heard everybody’s voice.”
Martin’s Super Markets started experimenting with doors on medium-temperature cases about five years ago, partnering with Remis America, Elkhart, Ind. Starting with dairy cases only, the chain is now putting all of its dairy, about half of its produce, and all of its prepacked meat in cases with doors.
In its newer stores, cases come equipped with doors. In older stores, Martin’s has done door retrofits in three stores, with another four planned for the coming year. “The next big step is retrofitting doors on fresh meat cases — and I don’t know if I’ll win that argument,” said Alwine. “But I think we heard at [the FMI Energy & Store Development Conference] that by 2020, doors on refrigerated case will be required. So I think it’s something that we have to figure out how to do.”
As for whether doors adversely impact sales, “We don’t have an answer either, but we find that the perception of the customer is positive and most of the problem is uncertainty coming from merchandisers,” Alwine said.
Gallego noted that BJ’s doesn’t have an option for doors for much of its fresh meat, fish and cheese, which is on the sales floor in low profile cases. “We do have some [cases] along the wall for produce and some deli that we could retrofit, but a lot of our opportunities are gone because of our case selection.”
Retailers can also save energy by making sure that stores are not operating at full capacity when demand and rates are highest. To that end, Hy-Vee uses its refrigeration contractor to oversee control strategies and the sequencing of refrigeration compressors. “So if we have a power failure and it comes back on, say, at 4 in the afternoon on a summer day when your demand is the highest, then we’re not banging everything on at one time,” said Scanlan. “We count on those guys.”
Target has an energy team that works closely with utility suppliers to “truly understand all aspects of our energy consumption” and fully take advantage of their suggestions, said Anderson. On the HVAC side, BJ’s is testing some staging controls to make sure that compressors don’t all start at the same time at peak hours.
Some of the roundtable retailers are testing renewable energy sources. Hy-Vee, for example, has two applications that just launched within the last month — solar panels on the overhead fueling canopy at one of its convenience stores and a small solar installation at a new store in Urbandale, Iowa. But Hy-Vee faces a challenge in achieving an ROI for solar power because its blended utility rate in Iowa and surrounding states is low — roughly 6 cents per kilowatt-hour, noted Scanlan.
At BJ’s, roughly 8% of its 200 clubs have some type of solar energy panels, said Gallego. Some of the older ones have 20-kilowatt systems to handle light loads. Recently, the company has added some 750 kilowatt systems that are running the clubs strictly with solar power — and putting energy back on the grid. BJ’s is getting ready to implement one-megawatt solar panels in its distribution centers.
Target has applied solar technology in California, Hawaii and New Jersey stores, and is also looking at adopting fuel cell technology in a few stores, said Anderson.
The supermarket executives at the roundtable have tended to stay away from trying to save energy by reclaiming heat from their refrigeration systems to heat the store, a process that requires additional refrigerant. However, some, like Hy-Vee, do use it for hot water preheating.
BJ’s also sticks with water reclaim to preheat hot water. As a member of the EPA’s GreenChill program, the chain shies away from heat reclaim because it requires piping, coils and other components that increase refrigerant leak potential — something GreenChill is trying to eliminate, said Gallego.
But Anderson pointed out that in some future refrigeration systems, which may not be as efficient as current systems, “the energy savings truly comes when you can apply heat reclaim.”
The compressor — the part of a commercial refrigeration system that compresses the refrigerant and makes cooling possible — needs to be managed to optimize energy savings. Here is a brief list of terms related to controlling energy use in the compressor and other key parts of the system.
Suction: Side of compressor that pulls in the cool refrigerant gas coming back from cases.
Suction pressure: Pressure of gas entering compressor.
Floating suction pressure: Allowing compressor suction pressures to vary with load conditions, saving energy.
Discharge (also Head): Side of compressor that discharges compressed refrigerant gas to condenser and then to cases.
Floating head pressure: Allowing compressor head pressures to vary with outdoor conditions, saving energy.
Subcooling: The process of cooling the already liquid refrigerant below its saturation temperature, increasing system efficiency. It ensures that a there is a full column of liquid refrigerant at the case evaporator.
Ambient subcooling: Using an oversized condenser or an additional heat exchanger to subcool liquid refrigerant.
Superheat: The number of degrees a vapor is above its boiling point at a particular pressure. It needs to be adjusted to make sure that the optimal amount of refrigerant is fed through the system and to prevent liquid from getting into the compressor.
Read more: Transcript of Refrigeration Roundtable
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