Grocery stores in the U.S. spend an average of $4.00 on electricity and 24 cents on natural gas per square foot annually. In a typical grocery, refrigeration and lighting represent between 44 and 77 percent of total use depending on climate, making these systems the best targets for energy savings
Although energy only represents about 1 percent of total grocery store costs, it is about equal to a typical grocery’s profit margin. Therefore, a 10 percent reduction in energy costs can mean a 10 percent increase in profits! To better manage your building’s energy costs, it helps to understand how you are charged for those costs.
Most utilities charge commercial buildings for their natural gas based on the amount of energy delivered. Electricity, on the other hand, can be charged based on two measures—consumption and demand. The consumption component of the bill is based on how much electricity in kilowatt-hours (kWh) the building consumes during a month. The demand component is the peak demand in kilowatts (kW) occurring within the month—or, for some utilities, during the previous 12 months. Demand charges can range from a few dollars per kilowatt-month to upwards of $20 per kilowatt-month. Peak demand can be a considerable percentage of your bill, so care should be taken to reduce it whenever possible. As you read the following energy cost management recommendations, keep in mind how each one will affect both your consumption and demand.
Here are some fixes you can do:
Turning Things Off
It’s the simplest of ideas, and it doesn’t require much more than staff training.
Remember that every 1,000 kWh you save by turning things off equals $100 off
your utility bill (assuming average electricity costs of 10 cents/kWh).
Cleaning and Maintenance
Check the economizer. Many air-conditioning systems use a dampered vent
called an economizer to draw in cool outside air when it’s available,
which reduces the need for mechanically cooled air. The linkage on the damper,
if it’s not regularly checked, can seize up or break. An economizer that’s
stuck in the fully open position can add as much as 50 percent to a building’s
annual energy bill by allowing hot air in during the air-conditioning season
and cold air in during the heating season. Have a licensed technician calibrate
the controls; check, clean, and lubricate your economizer’s linkage about once
a year; and make repairs if necessary.
Longer-Term Solutions
Although the actions described in this section require more extensive
implementation, they can dramatically increase the efficiency of your store.
Ask the professionals at CLS for an analysis to help prioritize or initiate
such projects.
Optimize Refrigeration
The optimization of refrigeration systems can reduce energy use by 24 percent
relative to standard practice. The following measures yield the largest
savings.
Consider Thermal Energy Storage
Adding thermal energy storage like the Ice Bears can reduce a large percentage
of demand charges and shift energy usage to lower cost off peak hours.
Ice bears are easily integrated into most common rooftop a/c units and (soon)
refrigeration units to provide cooling from a tank of frozen ice that was made
at night during off peak or hours when the store is closed. Then, when
cooling is needed during the hottest peak of the day, your a/c units will be
resting and only blowing cold air from the melted ice of the ice bears.
Consider Combined Heat and Power
Combined heat and power (CHP) plants generate electricity at the point of use
and allow the heat that would normally be lost in the power generation process
to be recovered to provide necessary heating and cooling. CHP plants can power
store equipment and provide backup power generation when grid power is
unavailable, which serves to prevent product loss; they can also provide hot
water and auxiliary cooling for the facility. In one example, a Whole Foods
store in Brooklyn, New York, installed a 157-kW CHP plant to power chillers,
provide hot water, and provide power in the event of a power outage. Read more
about the steps this store took in the SustainableBusiness.com
article Whole Foods Brooklyn Store Is
Consider Desiccant Dehumidification
In humid climates, much of the energy used in air conditioning goes to removing
moisture from the air. Desiccant dehumidification can be a cost-effective
solution for removing this moisture because it uses natural gas instead of electricity.
In some cases, air-conditioning equipment can be smaller because it only gets
used to cool dry air.
Upgrade to More Efficient LED Lighting and Smart Controls
Lighting is critical to creating ambiance and making merchandise attractive to shoppers. High-quality lighting design can reduce energy bills and drive sales. It directly impacts sales. Fluorescent fixtures can be replaced with LED fixtures, LED retrofit kits, or LED tubes.
Replace incandescent lightbulbs with LEDs. Wherever an incandescent lightbulb is installed that’s on for longer than two hours per day, replace it with an LED. These lower-energy options are three to five times more energy efficient than incandescent bulbs, last at least 10 times as long, and—because they give off a minimum of one-third as much waste heat—reduce the loads on the store’s cooling equipment. For freezer applications, specify LEDs, which work well in cold conditions.
Install occupancy sensors in walk-ins. By replacing light switches with low-temperature occupancy sensors, you’ll reduce lighting energy consumption by about half.
Refrigerated display case lighting. The efficiency of LEDs improves in cold operating environments (unlike linear fluorescent systems, the light output of which drops in low temperatures). LEDs are also directional in nature, allowing for less wasted light. As a result, LED case lighting can cut lighting energy use by more than 40 percent compared to T8 fluorescent lamps.
LEDs can also be tied to occupancy sensors so that the cases are only illuminated when shoppers are present. This is a particularly easy savings opportunity for supermarkets that remain open 24 hours a day. When Walmart initiated a pilot LED program integrating occupancy sensors into its LED display lighting, the company estimated the total time lights were on would drop from 24 to 15 hours per day—a 38 percent reduction. Occupancy sensors aren’t typically used for cases that are illuminated by fluorescent lighting because frequent switching reduces the life of fluorescent lamps, but it has no impact on LEDs. This approach also lengthens the life of LEDs—the more time the LEDs spend turned off, the longer the lamps will last.
The use of LEDs also reduces case compressor loads. Because the cases can use lower-wattage lamps, there’s less heat to dissipate. Additionally, the heat sink for an LED can be positioned to allow at least some of the heat to dissipate outside the case. With fluorescent lighting, most of the waste heat must be offset with additional cooling inside the case. When LEDs are used with occupancy sensors, they’ll spend less time in the on mode and therefore contribute less to the cooling load. LEDs also provide more even light distribution, can be dimmed, have a very long lifetime, and have been shown to appeal to shoppers at significantly greater rates than linear fluorescent lighting.
Use Smart Lighting Design in Parking Lots
Reduce light levels. Parking lots are often overlit—an average of 1
foot-candle of light (sometimes less) is usually sufficient. Dimming and
occupancy-sensing controls can also add to energy savings in parking lots.
Install more efficient light sources. The most common lamps in outdoor lighting are high-intensity discharge (HID) sources—metal halide and high-pressure sodium (HPS). Fluorescent and induction lamps are also used in parking lots, but LEDs have become the most efficient alternative as their performance has improved and prices have come way down.
LEDs can be a good choice for parking lots because the fixtures perform well in the cooler conditions that are typically found outside at night, and because LEDs work better with controls than HID products do. LEDs also offer long life (which reduces maintenance costs), they provide more even light distribution, and they produce less light pollution and light trespass—properties that improve aesthetics and contribute to energy savings. For example, in recent field testing, the US Department of Energy (DOE) found that LEDs had only somewhat higher efficacy than HPS lamps, but that LEDs provided substantial energy savings thanks to lower overall light levels enabled by better uniformity and less light pollution. The one downside is that users should be wary of the potential for glare. A parking lot retrofit of LEDs cut lighting energy use by 70 percent in the DOE-monitored Application Assessment of Bi-Level LED Parking Lot Lighting (PDF) at a Raley’s Supermarket in California.
Consider Reflective Roof Coating
Painting the roof of a grocery store with white or other highly reflective
paint can reduce the energy required for summer cooling by 25 to 65 percent and
help trim peak demand, as well as increase the life of the roof. CLS uses an
anti-microbial flexible nano-coating that can extend roof life indefinitely.
Consider Comprehensive Upgrades – paid from savings
Some owners or tenants wait until they have budget for upgrades which is
usually insufficient for a comprehensive upgrade. The result is piecemeal
improvements that cost more than they need to and often poorly engineered and
without regard to utilizing the most effective mix of cost saving
measures. For example, limited lighting retrofits may have a 1.5 year
payback and 10% savings while refrigeration upgrades like those above may have
a 4 or 5 year payback and triple the cost savings at 30%. But by
piecemeal approach, the longer payback HVAC or refrigeration upgrades may never
get done. However, a comprehensive project combing the lighting,
refrigeration, HVAC and a sprinkling of more than 500 measures at CLS’s
disposal may have a combined 2.5 or 3 year payback with 50% savings.
Include off balance sheet financing and the payback is instantaneous – a much
better deal in the short and long run.