Counting Kilowatt-Hours: How to Measure and Reduce Your Electricity Use

Reader Contribution by Staff
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How much electricity is your computer using right now? It’s surprisingly easy to find out using a simple electrical meter, such as a Kill a Watt. Right now, I have a Kill a Watt hooked up to my PC, and it shows that I’m using 92 watts of electricity.

 Actually, the figure fluctuates, depending on how hard I’m making the processor work at any given moment. But since I plugged this particular meter into my computer 39 hours ago, it’s used about one kilowatt-hour of electricity.  So what does that mean? What exactly is a kilowatt-hour anyway? Here’s a quick review:

• One kilowatt-hour is equal to one kilowatt consumed over one hour. And one kilowatt is equal to 1,000 watts. (For more energy measurements check out this handy chart from the Energy Information Administration.)

• On your electric bill, you’re charged based on the number of kilowatt-hours (kWh) you consume. For the United States, the average cost of one kWh is about 10 cents.

• For even more math fun, you can consider that this one kilowatt-hour is equal to roughly 2 pounds of greenhouse gases, because electricity in the area where I live comes primarily from coal.

So here’s another interesting question: How does my computer compare to other computers? Well, last week we hooked up a Kill a Watt to another editor’s computer, and his laptop was only drawing about 30 watts of electricity. Humph. Oh well, I suppose it’s not a competition.

But the possibilities for measuring and figuring out how to reduce your energy use are endless. For some great ideas, check out this article from Gary Reysa, with his Eight Great Energy Saving Projects. He measured the energy savings of eight different projects and calculated the dollar savings and reduced carbon emissions for each one. You can find even more of these projects on his Web site,

Photo by Megan Phelps 

Megan E. Phelps is a freelance writer based in Kansas. She enjoys reading and writing about all things related to sustainable living including homesteading skills, green building and renewable energy. You can find her on .

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