If you’ve shopped for large appliances lately, or even wandered near the appliance section at a home improvement store, your eyes have been scorched by those bright yellow “EnergyGuide” labels.

They’re meant to help you compare the energy costs of different models, showing how much electricity the appliance is expected to use and how that translates into the yearly cost to run it.

Which is awesome when you’re trying to decide among the hundreds of available options for refrigerators. Figuring out how much you’ll actually save in the real world, however, takes some more digging.

## Your costs may vary

Here’s the thing: Those yellow labels are based on national averages for electricity costs. Not only is that a moving target, but your actual cost may be lower — or a lot higher — depending on energy costs where you live and how much you use the appliance.

Still, the EnergyGuide gives you enough information to start figuring out how much you’ll save compared with the appliances you have now.

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One way to gauge appliances’ energy use is to buy an electricity usage monitor for about \$20. These work with any device that runs on 120-volt electricity, including refrigerators, microwaves, most washing machines and clothes dryers that use natural gas. The monitors don’t work with large household appliances that require 240 volts, such as central air conditioners, electric clothes dryers and water heaters.

Or you can do a little math. Here are the steps:

Estimate the daily run time. If your clothes washer runs about seven hours a week, that translates into one hour a day. Figure that refrigerators, which cycle on and off, actually run about one-third of the hours you have them plugged in, or eight hours a day. An appliance that runs 15 minutes a day — say, a toaster — would translate into 0.25 hours of daily use.

Find the wattage of the appliance. Sometimes it’s on a label or stamp. If not, the volts and amperes (amps) the product uses are often listed; multiplying those two numbers will estimate the wattage. This information may also be found in the owners manual or with an Internet search.

Calculate the daily energy consumption. The formula is:

Wattage

X hours used per day

Then divide the answer by 1,000.

Figure the annual use:
Daily energy consumption

X number of days the appliance is used per year

Multiply by your energy cost. Which you can find on your latest utility bill.

Here’s how the math worked for our old refrigerator, which had no wattage listed but showed 115 volts and 5 amps on a label inside the door.

• Multiply 115 volts times 5 amperes to get 575.
• Multiply 575 by the hours of daily use, 8, to get 4,600.
• Divide that result by 1,000 to get 4.6 kilowatt-hours of daily consumption.
• Multiply daily consumption by 365 days a year to get 1,679 kwh.
• Multiply yearly consumption (1,679) by our cost of electricity (17.2 cents per kwh, or .172) to get \$289.

## What the math means

The new refrigerator I’m considering has an estimated annual electricity use of just 563 kwh — not surprising, since energy efficiency has improved dramatically since our unit was manufactured in 1998. Multiplied by 17.2 cents, our annual cost for the new one would be roughly \$97 — higher than the \$68 estimated cost on the EnergyGuide label, but a \$192 savings over what we’re paying now. So over 10 years, I can expect the \$1,900 icebox to pretty much pay for itself just in energy savings.

Sweet. Excuse me while I go order a new fridge.