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Power and energy, they are the same thing…right?

10 August 2012

When you open your utility bill, do you jump straight to the numbers at the bottom without reading the rest? Unfortunately, most people don’t understand what they are paying for,  how it is measured nor how it connects to the electronics and appliances they are using.

Energy and Power are often used interchangeably but they aren’t the same thing in reference to units of energy. Gosh, so technical- but here we go!

Energy=Power x Time   Power=Energy/ Time  <– For all you math oriented people.NokWperHr.gif


  • An amount of energy is KWh (kilowatt- hour NOT kilowatt per hour)
  • Energy is a measurable quantity that you can buy.
  • An ability to do work.
  • The amount of KWh you use determines how much you pay on your elctric bill


  •  A Rating of power is a watt or kilowatt (watt/1000).
  • The rate that energy is being used and work can be done.
  • Appliances and electronics are measured in their power consumption.

Analogy and examples:

  • Kilowatt-hours (energy) are like gallons of water.
  • Kilowatts (power) are like gallons per minute.

Watts x hours used /1000 x price per kwh= cost of electricity

  • If you use a 1000 watt air conditioner  for 1 hour, you have used 1 kilowatt-hour.

Woofta, hopefully only semi-painful, and super informative! Now, I dare you to look at your electric bill next month and read it all- and understand how much energy you are using as a result of the amount of time your used your electronics and appliances.

Green Building Advisor;  Mr. Electricity

One Comment leave one →
  1. 10 August 2012 2:40 pm

    …. which is related to why phantom power is so insidious – it’s the time multiplier that gets you.

    If you have “only” an extra 100W lurking in “off but not off” appliances, that’s 100W x 24h x 31 days = 74 kWh per month, or an extra $80 per year or so of waste in your bill!

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