Greener Grocery Stores

Food retailers can realize significant savings if they make some energy-efficient upgrades to their refrigeration systems and display cases.

Supermarkets use more than twice as much energy as the average commercial building per square foot. Only hospitals and restaurants are more energy-intensive building types, according to the U.S. Energy Information Administration (EIA).

Energy Star, the government-backed energy program, estimates that the average annual energy cost of a typical food store is more than $4 per square foot, meaning that the typical 50,000-square-foot supermarket generates utility bills totaling more than $200,000 per year. Given the grocery industry's historically thin profit margins, Energy Star also estimates that saving $1 on energy costs has an impact on the bottom line equivalent to generating an additional $59 in sales.

This is ample justification for supermarket chains and individual stores to explore ways to reduce energy expenses, shrink their environmental footprints and create a better shopping experience for customers.

Refrigeration

Refrigeration accounts for about 47 percent of the energy used in a typical grocery store, according to the EIA. So it's easy to understand why many food retailers are looking in the frozen food, dairy and fresh food sections for energy-saving opportunities.

New-generation refrigeration systems and display cases are significantly more efficient than those developed even a decade ago. For example, distributed refrigeration systems use about 10 percent less energy than conventional back-room rack systems. They also are easier and less expensive to install and maintain because they use 50 percent to 75 percent less refrigerant piping and require 60 percent to 80 percent less refrigerant charge. These factors also improve environmental safety by reducing the incidence of coolant leaks.

A leading national food retailer installed a distributed refrigeration system as part of an integrated solution at a store in suburban St. Louis. Combined with other energy conservation measures, the system is expected to reduce energy usage by approximately 30 percent and cut greenhouse gas emissions by about 22.5 million pounds per year, the equivalent of taking about 60 cars off the road.

Another refrigeration system innovation is especially designed to save energy and reduce environmental impact while keeping foods fresh. Medium-temperature secondary systems use water and a propylene glycol mixture cooled by a low refrigerant charge. They use about 70 percent less refrigerant than, and produce about half the carbon emissions of, conventional systems.

Other opportunities for supermarkets to improve refrigeration system energy and environmental performance include implementing a refrigerant leak inspection and repair programming, upgrading refrigeration system components, and conducting regular maintenance, including cleaning system coils.

Display Case Innovations

Adding doors to dairy, deli and cold beverage cases can help retailers reduce energy consumption by an estimated 65 percent compared with open cases, and create a more comfortable environment for shoppers.

By upgrading its display cases, a suburban St. Louis natural food store reduced energy use, improved stocking efficiency and increased merchandising space by 33 percent. Changes included the installation of night curtains in multi-deck cases, which can block an estimated 70 percent of the ambient heat that normally enters an open display case, reducing energy costs while a store is closed at night.

Supermarkets can also reduce the energy consumption of display cases by installing no-fog doors to reduce door openings, performing regular maintenance such as cleaning discharge and return grilles, and updating or replacing inefficient cases with the latest energy-efficient options.

LED Case Lighting

Recent improvements in light-emitting diode (LED) case lighting technologies have made it more appealing — and economical — for grocers to replace the florescent lighting in refrigerated display cases with LED lights. Grocers typically recoup the cost of an LED retrofit in 30 months or less with energy savings.

LED lights are much more cost-effective than fluorescent lights, using significantly less energy and lasting as much as three times longer. In addition, LEDs generate less heat when installed in a refrigerator or freezer case, reducing refrigeration system workload and helping to maintain constant temperatures within the case.

The most effective lighting retrofits include installation of motion-sensing systems that can be set to dim the lights in display cases when there's no traffic in the aisle and restore full lighting when a customer or employee approaches the case. Depending on traffic levels, motion sensors can generate an estimated 20 percent in additional energy savings compared with conventional lighting systems without dimming capabilities.

A California utility and a supermarket recently teamed up to test the effect of retrofitting reach-in freezer cases with LED lights and motion sensors. The combination of LED lights and motion sensors reduced energy consumption by 68 percent compared with the T-8 fluorescent lamps and electronic ballasts they replaced. In addition, because LEDs have an estimated lifespan of 50,000 hours, vs. a T-8 fluorescent tube's 15,000-hour life expectancy, the store estimates its monthly service fees for lamp replacement have dropped by 20 percent.

A Complementary Approach

While refrigeration accounts for close to half of a typical supermarket's energy use, supermarket chains and individual stores can be most successful by taking a whole-store approach to their energy-efficiency efforts, including heating, ventilating and air conditioning (HVAC) and store lighting.

More information on creating a greener grocery is available at www.energystar.gov and at www.hussmann.com.PG

Michael J. Higgins is VP of marketing, strategic planning, and business development for Bridgeton, Mo.based Hussmann Corp.