Thursday, March 03, 2005


The more I look into environmentalism and energy policy, the more it becomes clear that conservation is the best way to go. Using less, and in particular less energy, has positive benefits that stretch from the environment to geo-politics (see earlier post on Geo-Greens).

For me, the first part of this is figuring out how much energy I actually use. Then I would like to figure out ways that I can use less of it while accomplishing the same activities.

But getting good numbers as to how much energy you are using is tricky. I know how many total kilowatts of electricity a month I use, but I don't know how much electricity each device I have plugged in takes up. How many kwh does it take to run my computer and monitor for an hour? You can look at the documentation and they will tell you how much maximum energy they can draw (usually measured in amps) but not how much on average they draw.

So I found this cool tool called the Kill-A-Watt (this is a good review of it with pictures). It is a small device that plugs into a wall and then you plug your device into the Kill-A-Watt. It tells you how many amps, volts, watts and a ton of other stuff I don't understand that you are drawing.

I would highly recommend picking one up and figuring out where your electricity is going.

I use about 8kwh a day, of which 1.8 goes to the fridge, 2.2 goes to my computer, 1.4 goes to the TV/Replay/Stereo, .9 goes to lighting and 1.3 is unaccounted for (stove, washer dryer, mircowave or something else).

For me I found out that my computer uses 85 watts to run normally but uses an extra 40 watts when the CPU is maxed. I like to run one of those screen savers that tries to cure cancer in the background. Now I know that it costs an extra 40 watts for every hour it runs. Considering I could put the computer in standby mode (which only takes 2 watts) it is taking 125 watts to run. Over a full day that would be 3kwh or about $.30. Not super expensive but still quite a bit considering my refrigerator takes about 1.75kwh a day.

My 19" Monitor uses 70W. My laptop on the other hand only uses 23 on average and 35 on high CPU usage. The laptop is only using about 1/7 the power of my desktop machine. So using that saves me a lot of juice.

My plasma TV hasn't helped my efforts. My old TV was using 80W on average. The plasma is using 170W. Plus it uses 16W when it is "powered off". Don't know what's up with that. Must make it quicker to turn on or something. The ReplayTV uses 34 watts but is on 24/7 so it takes .8kwh to run each day. Not that it is a big draw but it seems like it ought to have a standby mode for when you aren't watching and it isn't recording.

And for those of you that are wondering a Foreman grill uses 770 watts. Don't know how that compares with my stove because I can't measure that.

Anyway, as you can tell I was having lots of fun measuring every device in my house and I recommend everyone do the same.


Anonymous said...

Thank you for the information! Very useful to get some view over the energyconsumtion of those things we are so used to. Strange enough, it is not easy to find inorfmation about energy effeciency of products at the manifacturers. Not impossible, but not easy either.

Regards from Sweden!

Fat Knowledge said...


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