How much electricity does a 500 watt fridge use?
My refrigerator has a 500 watt compressor that runs about one fifth of the time. I am paying $0.13 per kilowatt hour. How much electricity does my fridge use per month and what will it cost me?
Assuming I could find another refrigerator with only a 350 watt compressor, how much money would I save per month, and how much should I be willing to pay for the new fridge so that it pays for itself in five years?
Answer from Green Energy Efficient Homes
You shouldn’t really be looking at the watts consumed by a refrigerator as a measure of its efficiency or its operating cost. Think of a refrigerator as analogous to a car, and the wattage of the compressor as analagous to the horsepower of the engine. You can’t predict the gas mileage of the car based on the horsepower. Similarly, “watts consumed by refrigerator” only tells you how much power the refrigerator draws while the compressor runs, not what the unit will use over a given time period or how long the payback period will be.
Just as two cars with the same horsepower can have radically different gas mileage, two refrigerators with exactly the same compressor (not just the same wattage) can have different energy efficiency. How much insulation does each refrigerator have? How many cubic feet of interior space? How is that space divided between the fridge and freezer compartments? How good are the gaskets? All these factors will affect your refrigerator energy usage and payback period for an upgrade to a more efficient model, much more than the compressor wattage.
To determine the watts consumed by a refrigerator over a time period – typically per month – look at the energy efficiency rating provided by the manufacturer. This rating should be provided on an EnerGuide or other data sheet provided with the refrigerator. It will list the kilowatt hours consumed per year. Multiply that figure by your price per kilowatt hour to get the cost per year for running the refrigerator.
If you’re comparing two new refrigerators it’s relatively easy to determine the payback period for buying the more expensive one. Let’s assume there are two refrigerators you’re considering, the Inglis I8RXCGFXQ top freezer (475 kwh per year, $549 price tag) and the Whirlpool G9RXXFMWB top freezer (343 kwh per year, $779 price tag). You can determine the operating cost of each freezer based on their annual kwh consumption and your electricity cost:
- Inglis I8RXCGFXQ: 475 kwh/year @ $0.13 = $61.75
- Whirlpool G9RXXFMWB: 343 kwh/year @ $0.13 = $44.59
By substracting the lower from the higher yearly operating cost you can determine the savings per year. In the above example, the Whirlpool G9RXXFMWB saves you $17.16 per year, but costs you $230 more up front. If you divide your annual savings by the added up front cost you can determine the payback period: $230 / 17.16 = 13.4 years.
If you’re trying to compare the watts consumed by a refrigerator you already own, to that of a refrigerator you plan to buy, the best approach is to buy a Kill A Watt meter or other electricity usage monitor and use it to measure your current refrigerator energy consumption. I’ve owned a Kill A Watt meter for years and it is very handy for this type of measurement, as are other inexpensive electricity meters such as the Belkin energy cost monitor. You can use either of these devices to measure the electricity consumption of your current refigerator over at least a 3 day period, divide the kilowatt hour reading by the number of hours of measurement, and multiply by 24 to get your daily consumption. Then multiply that by 365 to get annual consumption. For example, I plugged my Kill A Watt meter into my Maytag 18.5 refrigerator and left it in for about 3 days. After 74 hours and 53 minutes the Kill A Watt meter registered 3.96 kwh. Here’s how I determined the watts consumed by my refrigerator per year:
- 74h53m = 74.88 hours
- 74.88 / 24 (hours per day) = 3.12 days
- 3.96 kwh / 3.12 days = 1.269 kwh / day
- 1.269 kwh/day X 365 days = 463 kwh / year
That gives you an easy figure to compare new refrigerator efficiencies to the watts consumed by your current refrigerator.
If you want to find refrigerator efficiencies for both current and recently discontinued refrigerator models (since some retailers will carry older stock), I suggest you check the Canadian government energy efficiency site (Formerly at http://oee.nrcan.gc.ca/residential/business/manufacturers/search/refrigerator-search.cfm?attr=4 but as of March 2015 it seems all the Office of Energy Efficiency links are dead), because it includes both ENERGY STAR rated fridges (ones that are at least 20% more efficient than the base requirement for refrigerator efficiency) and refrigerators that don’t meet the ENERGY STAR requirements).
In my experience, refrigerator salespeople don’t really understand energy efficiency and will try to convince you that whatever they’re selling is efficient. If you don’t see an Energy Guide label for the refrigerator you’re considering, do some research yourself. It just doesn’t make sense to buy a new refrigerator without looking at its power consumption and operating cost.