City of Roseville

Average energy-use data

Figure 1: Energy consumption by end use

On the national level, grocery stores use the largest portion of their electricity to run refrigeration and lighting systems. Space heating and cooking dominate natural gas use.

You’ll be better able to manage your store’s energy costs if you understand how you’re 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.

Figure 2: Diagram of a hypothetical daily load shape

Energy-efficiency measures reduce consumption and lower monthly peak demand charges.

Monthly demand charges can range from a few dollars per kW to upward of $20 per kW. Peak demand can be a considerable percentage of your bill, so take care to reduce it whenever possible. As you read our recommendations on managing energy costs, keep in mind how each one will affect both your consumption and your demand.

Quick fixes

Turning things off

It’s the simplest of ideas and doesn’t require much more than staff training. Remember that every 1,000 kWh you save by turning things off equals $120 off your utility bill (assuming average electricity costs of $0.12 per kWh).

Turning things down

Some equipment can’t be turned off entirely, but turning it down to minimum levels where possible can save energy.

Cleaning and maintenance

Longer-term solutions

Although the actions described in this section require more-extensive implementation, they can dramatically increase the efficiency of your store. Ask your local utility representative for more information about initiating such projects.

Optimize refrigeration

Optimizing refrigeration systems can reduce energy use by 24% relative to standard practice. The following measures yield the largest savings.

Consider combined heat and power

Combined heat and power (CHP) plants generate electricity at the point of use. They 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 your store’s equipment and provide backup power generation when grid power is unavailable, preventing product loss. They can also provide hot water and auxiliary cooling for the facility.

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 has to cool dry air.

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 still uses T12 fluorescent lamps, relamping with high-performance T8 lamps and electronic ballasts can reduce your lighting energy consumption by 35%. 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 areas that aren’t always in use, and payback periods of one to three years are common.

LEDs can provide even greater savings. You can replace fluorescent fixtures with LED fixtures, LED retrofit kits, or LED tubes. New fixtures are the most efficient alternative; LED tubes are the easiest, but they may not provide adequate light levels or light distribution.

Because the efficiency of LEDs improves in cold operating environments (unlike linear fluorescent systems where the light output drops in low temperatures), they’re ideal for refrigerated display-case lighting. 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% compared to T8 fluorescent lamps.

You can tie LEDs 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% reduction. Occupancy sensors aren’t typically used in cases with fluorescent lighting because frequent switching reduces the lamps’ life. However, switching doesn’t affect LEDs. In fact, it lengthens their life—the more time the LEDs spend turned off, the longer the lamps will last.

Using 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, are dimmable, have a long lifetime, and appeal to shoppers at significantly greater rates than linear fluorescent lighting.

Use smart lighting design in parking lots