Supermarkets and grocery stores are a $6.8 billion industry that has seen slow but steady growth in the past five years. Recent events have also shown how essential this industry is to American well-being. However, supermarkets operate on very low profit margins, about 1-2% of sales, with very high overhead. By far a grocery store’s highest expense is product inventory (food) at around 75%. Next is labor at about 10% of its expenditure.
That doesn’t leave much left over for all the other costs of running and maintaining a business. While energy costs are only about 2% of revenue, 56% of a supermarket’s total electricity load is refrigeration. The EPA estimates a 10% reduction in energy usage is equivalent to increasing net profit margins by 16%!
There are more than 38,000 supermarkets in the US and each one has on average of 10 walk-in cooler or freezer units. These refrigeration units must run 24/7; obviously there’s no turning them down at night when the store is closed, so finding strategies to save energy starts with the design of the system.
To understand the challenges of refrigeration technology, we need to look back at the Montreal Protocol of 1987. When scientists began to track the alarming depletion of the ozone layer, the international community met to create a treaty designed to phase out the use of ozone-depleting substances like chlorofluorocarbons (CFCs), commonly used as refrigerants and propellants. Next on the list were hydrochlorofluorocarbons (HCFCs) to be reduced by 2015. This spurred the measurement of a refrigerant’s ozone-depleting potential or ODP. Hydrochlorofluorocarbon (HFC) refrigerants like R-22 were developed that have a low ODP of 0.05 compared to CFCs which have an ODP of 1. Unfortunately HFCs have other concerns in that they are greenhouse gasses that contribute to global warming. Therefore the GWP or global warming potential is also calculated. To balance all this potential, a third score of total equivalent warming impact (TEWI) is used to verify a refrigerant’s overall sustainability. Supermarkets use the TEWI score to help gauge the aggregate climate impact of a refrigeration system.
The need to find low-GWP alternatives has led to the emergence of hydrofluoroolefins (HFOs) and so-called natural refrigerants like CO2, propane, butane and ammonia. One downside is that with the exception of CO2, these refrigerants are flammable, and NFPA, ASHRAE and other building and life safety codes must govern the safe use of these systems.
Supermarkets use several types of refrigeration cases, cooler rooms and freezers. There are the medium cooling, horizontal, open cases where cooled produce, meats and cheeses are displayed at about 35-38°F. These are the least energy efficient as all the air curtain cooling is released into the store. Usually at the back of the store you’ll find upright refrigerators with doors where dairy products are kept at 38°F, but these are just the front ends of much larger cold-rooms behind the main shopping floor. Most stores have many aisles of upright freezers where the coldest items are kept anywhere from -5 to -24°F. All of these display units are operated by refrigeration plants either in the back rooms or on the roof.
To operate these coolers and freezers several different types of refrigeration systems can be employed, including Direct Expansion and Secondary Loop systems. Both use refrigerant that cools the units, but then gains heat and must be cooled again. Refrigeration can be energy intensive, so designing an efficient system and keeping it efficient is important.
ENERGY SAVINGS TRENDS
The energy efficiency and safety of a refrigeration system depends on its optimal performance. The EPA estimates that a typical large supermarket refrigeration system holds about 4,000 pounds of refrigerant and has an annual leak rate of about 25% or 1,000 pounds. Not only does this make the system need constant maintenance, but it exemplifies the concern for higher OPD refrigerants being released into the environment. Couple that with possible flammability of some coolants, and supermarkets need to do all they can to ensure the security of their systems.
Other technology includes distributed systems that have all the mechanicals at or near the cases they serve. Smaller self-contained propane units contain only a small refrigerant charge (about 5.3 ounces per refrigerant circuit) and have a low leak rate of about 2%. Depending on the size, a store using only self-contained refrigeration equipment would only need 110 pounds of propane. That’s a significant refrigerant reduction!
Uncertainty regarding which refrigerants might be on the next phase-out list means supermarkets have to make smart choices today. And they want to. Many supermarket leaders are pledging to go to net-zero buildings with low TEWI refrigeration scores.
SOLUTIONS PORTFOLIO FOR SUPERMARKETS
The refrigeration systems in supermarkets need to function at top performance to attain the energy-efficiency that they need, which means they require the proper insulation. Armacell’s insulation systems are ideal for insulating miles of liquid and suction lines, chilled water piping, chillers and cooling tanks. Insulating pipes, refrigeration lines or HVAC cooling systems not only promotes energy efficiency, but it also prevents condensation on below-ambient temperature surfaces—a critical issue for supermarkets and grocery stores.
Specifying Armacell Solutions for Supermarket Solutions Portfolio is prudent for several reasons. Offering three package levels each tailored to code compliance, system performance and budget make specifying the right insulation for the right systems easier. Our products are always fiber-free, formaldehyde-free and low VOC making them an excellent option for any environment, eliminating particulate that can jeopardize air quality and equipment. Its closed-cell structure also prevents moisture ingress and naturally resists the growth of mold and mildew. Building owners and occupants can rely on Armacell insulation retaining its thermal integrity over time, lasting well into the future.
Read more about the benefits of Armacell’s Supermarket Solutions Portfolio in the eBook.