Grocery Stores Can Benefit From LED Lighting

Grocery stores in the U.S. use an average of 52.5 kilowatt-hours (kWh) of electricity and 38,000 Btu of natural gas per square foot annually. In a typical grocery, refrigeration and lighting represent about 47% of total use (Figure 1), making these systems the best targets for energy savings.

Energy costs account for 15 percent of a grocery store’s operating budget. Because grocery stores’ profit margins are so thin – on the order of 1 percent – every dollar in energy savings is equivalent to increasing sales by $59.

You will be better able to manage your building’s energy costs if you understand how you are charged for energy. 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 (Figure 2).

The consumption component of the bill is based on how much electricity, in 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. Monthly demand charges can range from a few dollars per kW to upwards of $20/kW. Peak demand can be a considerable percentage of your bill, so care should be taken to reduce it whenever possible. As you read these energy cost management recommendations, keep in mind how each one will affect both your consumption and your demand.

On Suggested Solution

Upgrade to more efficient lighting

Lighting is critical to creating ambiance and making merchandise attractive to shoppers. High-quality lighting design can reduce energy bills and drive sales. If your facility uses T12 fluorescent lamps, relamping with high-performance T8 lamps and electronic ballasts can reduce your lighting energy consumption by 35 percent. Adding specular reflectors and new lenses and reducing the number of lamps can double the savings. Occupancy sensors or timers can add further savings in storerooms and other staff-only areas. Paybacks of one to three years are common.

Changing refrigerated display-case lighting to light-emitting diode (LED) light strips saves energy and has been shown to appeal to customers significantly more than linear fluorescent lamps. LEDs are more than 40 percent more efficient than T8 lamps, provide a more-even light distribution, are dimmable and have a long lifetime. In stores that remain opened 24 hours a day, LEDs can be tied to occupancy sensors so the display cases are only illuminated when customers are present. The waste heat from LEDs can be dissipated outside the case, something fluorescent lighting can’t do, resulting in reduced refrigeration energy: For every watt in reduced energy consumption, there is an additional 0.48-watt savings from reduced refrigeration demands.

Grocery stores with high ceilings might want to consider using T5 lamps and indirect fixtures to boost both lighting quality and lighting efficiency. T5 lamps are far more energy efficient and offer better light quality than either the high-intensity discharge lights or the older-style T12 and T8 linear fluorescent lamps typically found in high-ceilinged stores.
Use Smart Lighting Design in parking lots

Most parking lots are designed with far more lighting than the 1 foot-candle or lower average that the Illuminating Engineering Society of North America’s Lighting Handbook (2000) recommends. Using lower-wattage bulbs can actually increase the safety of your lot – an overlit lot can be dangerous to drivers if their eyes cannot adjust quickly enough in the transition from highly lit to dark areas. When designing lighting for a new parking lot, consider low-wattage metal halide lamps in fixtures that direct the light downward, rather than high-pressure sodium lamps. Even with a lower wattage, a grocery store could safely use fewer lamps if this choice is made. Metal halide is less efficient than high-pressure sodium in conventional terms but it puts out more light in the blue part of the spectrum, which turns out to be easier for our eyes to see under low-light conditions.

LED lighting has emerged as an even more efficient parking lot option than high-intensity lighting. However, because the Energy Star program does not currently include parking lots in its list of acceptable LED applications and because LEDs’ high initial costs result in long payback periods, be sure to conduct a thorough analysis before you commit to LED lighting for your parking lot.