Estimating appliance and home electronic energy use

The gift-giving season is almost here and if you're trying to decide whether to invest in a more energy-efficient appliance or you'd like to determine how all those electrical gifts you will be getting for Christmas will affect your electricity load, you may want to estimate appliance energy consumption.

 You can use this formula to estimate an appliance's energy use:

 Wattage × Hours used per day × Days used per year ÷ 1000 = Kilowatt-hour (kWh) consumption per year

 For example:

Personal computer (120 Watts) and monitor (150 Watts):

(120 Watts + 150 Watts) × 4 hours per day × 365 days per year ÷ 1000 = 394 kWh/year

 Then, calculate the annual cost to run an appliance by multiplying the kWh per year by your local utility's rate per kWh consumed.

394 kWh × $0.104 (current national average) = $40.98 per year

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 settings (hairdryers), the actual amount of power consumed depends on the setting used at any one time.

 Here are some examples of the range of nameplate wattages for various household appliances:

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