Monday, December 1, 2008


I borrowed a friend's Kill-A-Watt to do some power testing around my house. For years I'd been eyeing an old electric pencil sharpener from the 1980's and wondering if it was drawing too much energy. Well, the short report is that I didn't find any sneaky ancient energy-wasters like I was hoping. In general, I was surprised at how little power most things used! The only exception is the Plasma TV's, but we'll get to hat in a minute.

My house used 2000 Kilowatt Hours (KWH) last month. A quick glance at my last few electricity bills shows that's a little high but not out of line. The power company charges me about 8.7 cents per KWH. So let's take a look at how many watts are used by some different computer things in my house.

By knowing how many watts a device is drawing, I think you can calculate the dollar amount per month like so:

Watts x <24> x <30> / <1000> x $0.087.

Or to make it short

Dollars per month = Watts x 0.0626

So with that simple calculation let's look at these values I recorded. Not all of these are on 24 hours a day though.Old Linux Server (34) Watts = $2.13 per month Old Computer Speakers (8 Watts) = $0.50 per month 2 x 42" Plasma Television (2x300 Watts) = $37.60 per month

10 lightbulbs at 50 Watts = (500 Watts) = $31.30 per month