How to calculate appliance energy usage

I used to conduct Residential Energy Audits on behalf of OPALCO, the local utility provider in San Juan County. Oftentimes, homeowners are completely unaware of how much it actually costs to run a particular appliance. But, it can be calculated easily!

If you’re trying to decide whether to invest in a more energy-efficient appliance or you’d like to determine your electricity loads, you may want to estimate appliance energy consumption. You can do so with this formula: Wattage × Hours Used per Day ÷ 1,000 = Daily Kilowatt-hour (kWh) consumption (1 kilowatt [kW] = 1,000 Watts). Multiply this by the number of days you use the appliance during the year to determine annual consumption. To calculate the annual cost to run an appliance, multiply the kWh per year by your local utility company’s rate per kWh consumed. Note: use eight hours as an average daily maximum wattage time for a refrigerator. Although turned “on” all the time, refrigerators actually cycle on and off to maintain interior temperature. For typical wattages of various appliances see our chart.