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Dear Science Man

Author: scienceman

Scienceman, can you help me better understand just what a kilowatt-hour is?

Of course! Understanding a kilowatt hour is crucial if we really want to understand and reduce our energy consumption. As we at Seventh Generation are working to reduce our carbon footprints by 20% by 2010, we are beginning by auditing our own homes with the common Kill-A-Watt Meter. Therefore, because this tool measures in kilowatt hours, this is also a very important concept for us Seventh Geners to grasp. One kilowatt is 1,000 watts, and you can probably reference watts most easily with a light bulb. Imagine how bright a 1,000 watt light bulb would be!! That’s a lot of power. Thus a kilowatt-hour is simply, how many thousands of watts per hour an appliance is using. It’s equivalent to burning 100 watt light bulbs for 10 hours or see this quote, courtesy of Treehugger, for more examples:

“For example, here is what 1 kilowatt-hour can allow you to do: 1200 electric shaves (> 3 years), slice 100 breads, dry your hair 15 times, 4 TV evenings, listen to 15 CDs, Use a small refrigerator for 24 hours, 20 microwave meals, drill 250 holes, 4 evenings of light with 60 W incandescent lamps or 20 evening of light with 11 W compact fluorescent light (note the higher efficiency of CFLs).”

According to Energy Efficiency and Renewable Energy (EERE), the typical American home is said to use 11,000 kilowatt hours per year. What contributes to all this power? See EERE’s chart below to gain a better understanding of the typical energy consumed annually by each of the following appliances and their corresponding costs.