How to Estimate Home Appliance Energy Use
There’s a very simple way to figure out how much energy your home appliances are using. I’m not a math genius, and I can accurately determine how much energy each appliance in my home is using.
The formula is:
(Wattage × Hours Used Per Day ÷ 1000 = Daily Kilowatt-hour (kWh) consumption(1 kilowatt (kW) = 1,000 Watts)
Determine the annual energy consumption by estimating how many days per year you use the appliance. Then, you can figure the annual cost by multiplying the kWh by using your local utility’s kWh rate.
Here’s an example of something you may use frequently – a personal computer and monitor.
(120 + 150 Watts × 4 hours/day × 365 days/year) ÷ 1000 = 394 kWh × 8.5 cents/kWh = $33.51/year
Adjust the numbers to what you use. If you don’t know the exact figures, make an estimate.
Many appliances have the wattage stamped somewhere on the unit itself. It may be on a metal plate along with the
manufacturer’s serial number. If you can’t find the wattage, you may find the amount of amps the unit consumes. If you find the amp consumption, multiply it by the voltage used by the appliance. For most household items, it’s 120 volts.
However, your electric stove and dryer are usually rated at 240 volts.
Beware of a condition known as “phantom load.” This is when appliances continue to use electricity even when they’re turned
off. Some common examples are your VCR, TV, stereo, computer, and many kitchen appliances.
You can prevent phantom load by either unplugging the appliance from the wall socket, or you can plug it into a power strip.
Turn off the power strip when you’re done using the appliance. This will save some money on your energy bill every year.
Here’s some typical wattage ratings for common household appliances:
Coffee maker = 900–1200
Clothes washer = 350–500
Clothes dryer = 1800–5000
Dishwasher = 1200–2400 (using the drying feature greatly increases energy consumption)
Clothes iron = 1000–1800
Microwave oven = 750–1100
Radio (stereo) = 70–400
Refrigerator (frost-free, 16 cubic feet) = 725
o 19″ = 65–110
o 27″ = 113
o 36″ = 133
o 53″-61″ Projection = 170
o Flat screen = 120
VCR/DVD = 17–21 / 20–25
Vacuum cleaner = 1000–1440
Water heater (40 gallon) = 4500–5500
Now that you know how to calculate energy consumption of common appliances in your home, it’s easier to figure out which ones you want to keep turned off as much as possible to save energy.