Save Money by Watching the Watts

P3 International's $21 Kill A Watt power monitoring device.
P3 International's $21 Kill A Watt power monitoring device.
We use a lot of electricity at my house, a drawback to being technology obsessed. In the interest of going at least a little bit greener, I set out to measure (and to reduce, I hoped) the power usage of my various home-office computers and peripherals during a typical workday. What I discovered was, uh, shocking.

To begin my testing, I picked up the Kill A Watt from P3 International, a $21 product that lets you measure the amount of power a given device uses. Then I perused my $75 electricity bill and discovered that the power company charges me roughly 11 cents per kilowatt-hour (kWh) for the first 333 kWh we use per month. (I also learned that the price per kWh goes up slightly for the next 100 kWh we use, and then it rises dramatically once we pass the 433-kWh mark--which we commonly do.) Armed with my new gadget and a little pricing knowledge, I headed for the power strips under my desk.

The Good, the Bad, the Insatiable

My company-provided Dell notebook sips responsibly from the power trough, consuming an average of 29 watts while in use and 20 watts with a dark screen (now set to occur after 5 minutes of inactivity). Standby pulls a mere 1 watt, and powered off it's a perfect 0. When I work at home, I use the notebook to monitor my e-mail, and the screen is dark half the time. I then shut it down after a 9-hour workday. In the end, I'm happy to pay roughly 2 cents a day to run this notebook.

My home-built desktop shows less restraint, drawing an average of 145 watts during typical use (though heavy video-card use can cause that number to spike up to 100 watts higher). In standby the unit pulls 6 watts; turned off, it still draws 3 watts. In the past I rarely powered it down, so I paid about 38 cents per day ($140 per year). Now I set the PC to enter standby mode after 25 minutes, and I shut it down at night, which should cut my cost by roughly half. My savings fall short of those from the Energy Star 4.0-rated "Green PCs" that the PC World Test Center saw recently, but they're a start.

I run two 22-inch flat-panels. One is an Acer that draws 37 watts while in use and 0 watts in standby and off; the other, a Westinghouse, pulls 43 watts while in use, and 1 watt in standby and off. For a 9-hour day with no standby, the cost is 8 cents. By setting the monitors to go dark after 10 minutes of inactivity and by turning off any power-wasting screen savers, I expect to keep my cost here at under $30 per year.

My other two must-run devices are my Scientific Atlanta cable modem (6 watts) and my Netgear router (4 watts). With various devices accessing these 24/7, I'm willing to pay roughly 3 cents per day to run them continuously.

I'm less inclined, however, to feed my Klipsch speakers and HP all-in-one printer continuously. Idle, the printer pulls 12 watts, and even in power-saving mode (or off) it sucks down 6 watts. Worse, the speaker rig draws 16 watts when silent, goes up slightly at moderate volumes, and rises a bit more at concert-level decibels. But the power switch is virtually inaccessible, and I never turn them off.

So I attached a power strip to the underside of my desk--where I can easily access the power switch--and plugged in the printer and speakers. Now both pull 0 watts until I decide to use them.

No change proved particularly difficult--we'll talk about my power-guzzling, always-on home server another time--but every little bit helps. It feels good to be a bit more green, and to save a little green on the power bill.

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