Which Uses More Energy: a Refrigerator, Dishwasher or Dryer?
A major difficulty facing homeowners concerned about the energy efficiency of their appliances is the difficulty of accurately measuring that efficiency. Energy efficiency depends on many factors, including the cost of energy, the age of the appliance and the manner in which the appliance is being used. Still, with some simple calculation we can arrive at an approximation of the energy efficiency of each appliance and compare it to the efficiency of other appliances in the home. Does this Spark an idea?
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Average Usage Estimations
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To aid homeowners in making informed decisions about the energy efficiency of their appliances, energy companies like the Otter Tail Power Co. frequently provide consumers with a list of the average energy usage of the most common home appliances for the purpose of comparison. These average rates are based on an average residential electric service rate of $0.0776 per kilowatt-hour and are rounded to nearest cent.
Comparisons
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Acknowledging that individual electricity usage rates may vary from home to home, the Otter Tail Power Co. estimates that refrigerators use anywhere from $4.66 to $9.31 in energy costs per year (depending on the size of the refrigerator), that dishwashers use anywhere from $1.12 to $5.59 per year and that dryers cost anywhere from $1.13 to $10.86 over a single year to operate. The wide range of clothes dryer costs is due in large part to whether the dryer is being used during "peak hours" or not.
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Other Considerations
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Comparative estimations of the energy usage of appliances can be useful, but the most accurate comparisons result only from calculating the energy usage of each appliance using a formula. If you are planning on replacing your current appliances with more energy efficient ones, government agencies and private sector groups such as EnergyStar and Underwriters Laboratories (UL) often rate appliances based on their energy efficiency, making it easier for consumers to make informed decisions about their appliance purchases.
Calculating Energy Efficiency
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As noted, energy efficiency depends on a large set of variables unique to your geographic area and indeed even your home itself. The United States Department of Energy recommends a formula that takes many of these variables into account. To calculate, you will need to know the cost per kilowatt hour that your utility company charges (printed on your electricity bill), the average number of hours per day and days per year that you use the appliance, and the wattage the appliance uses during one hour (typically embossed on the nameplate of the appliance). Multiply the number of hours per day by the appliance's wattage and multiply that number by the cost per kilowatt hour that you pay for electricity. You can multiply that sum by 30 to arrive at the cost per month of running the appliance or by 365 to arrive at the cost per year. The lower this total number, the more energy-efficient the appliance.
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