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August 08, 2006



...or the amount of electricity ten 100 Watt light bulbs consume in 1 hour. 1kWh = 1,000 Wh.

If you retrofitted those incandescent lamps with 23 watt CFL's it would take you more than 4 hours for 10 Lamps to consume 1kWh.



A kilowatt hour is about amount of power consumed heating a small electrical fire for one hour.


Wow, I just looked at my August energy bill (gas and electric) and found that we used 250 KWH of electricity this month. PG&E's "target usage" (not certain of the exact term) for us was something like 261 KWH. This is for a family of four with computers, cell phones and one small TV, in a 4 bedroom 1500 s.f. house in the Bay Area. No air conditioning. Plus we were home full-time for two weeks, busily using the computers.

I think I ought to be proud. NOw of course this is just electric, doesn't reflect the natural gas used to heat water and cook. But still.


For an ironing hour a flat iron consumes 1 kWh per use.


Good thing I hardly ever iron anything. :)


A kilowatt-hour is like a horsepower-hour, only 1.34 times as big.  Specifically, it's a unit of energy.  The basic MKS unit of energy is the joule; a watt is one joule/second, a watt-hour is 3600 joules (1 joule/second * 3600 seconds) and a kilowatt-hour is 3,600,000 joules.

(This may sound esoteric, but it's essential to understanding anything about energy and power.  The inability to grasp this basic distinction is the reason why most people cannot meaningfully understand or evaluate concepts about energy.  That's why unit analysis is taught in basic science courses and I harp on it too.)

Angus McDonald

A frustrating waste of power to me is a clothes dryer. They are often used on sunny days and consume about 4 kwh's of electricity per load. I have learned that a hydro-electric dam must convert the energy of 4,000 gallons of water, falling 150 meters, in order to create the electrical power necessary for a single dryer-load.

laundry man

Spin dryers are a simple yet practical way to dramatically lower your clothes drying costs & energy consumption. Spin dryers are over 100 times more energy-efficient than conventional tumble dryers. They only use about 300 watts, whereas
tumble dryers often use close to 5000 watts. The average household with a tumble dryer uses spends about $80 per year to dry the clothes, a figure that can be reduced dramatically with the use of a spin dryer.

Spin dryers use an extremely fast spin cycle to remove much more water from the clothes than a washing machine spin cycle. Our model has a 3200 rpm spin
speed, compared to the average washing machine spin cycle of 450-500 rpm. In addition, spin dryers are much gentler on your clothes and don't produce any lint. As a result, clothes will last longer.

You can read more about our Spin Dryer at http://www.laundry-
You can also read independent reviews at &


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