Estimating Appliance & Home Electronic Energy Use
If you are trying to decide whether to invest in more energy-efficient appliance or you would like to determine your electricity loads, you may want to estimate appliance energy consumption.
You can use this formula to estimate an appliance's energy use:
Wattage x Hours used per day x Days used per year divided by 1000 = Kilowatt-hour (kWh) consumption per year
Personal computer (120 Watts) and monitor (150 Watts): (120 Watts + 150 Watts) x 4 hours per day x 365 days per year divided by 1000 = 394 kWh/year
Then, calculate the annual cost to run an appliance by multiplying the kWh per year by Midwest's rate per kWh consumed.
You can usually find the wattage of most appliances stamped on the bottom or back of the appliance, or on its nameplate. The wattage listed is the maximum power drawn by the appliance. Since many appliances have a range of setting (hair dryers), the actual amount of power consumed depends on the setting used at any one time.
Examples of the range of nameplate wattages for various household appliances:
Clothes washer = 350-500 Watts
Clothes dryer = 1800-5000 Watts
Dishwasher = 1200-2400 Watts (heat drying further increases energy use)
Water heater (40 gallon) = 4500-5500 Watts
Source: U.S. Department of Energy - Energy Efficiency and Renewable Energy