Why do we care? Because of this simple equation: Power = Money
Electricity is not free and not likely to be anytime soon. In fact, in many areas the price of electricity is rising. Commonwealth Edison in Illinois just raised our rates a purported 24% for consumers. But that's an average bill that includes both the cost of the electricity and the cost of transmission. The transmission cost isn't changing. It's the energy cost that's coming off a rate freeze of 10 years. If you use more than the average amount of electricity, your bill will go up faster. If you can find ways to draw fewer kilowatt hours each month, you'll keep your costs at bay.
I'll have to admit I've been pretty casual about leaving my computer running for most of the day. Since it's used for business, I'm on it a lot writing blog posts, creating web pages, doing research and answering email. But these activities are spread out over about 12 hours every day. Not that I'm pounding the keys all that time. Actually, I'm in and out of the office a lot. I like to leave pages open on the screen and have them immediately ready when I sit back down. Does this sound like your office practice too?
The sticker shock of this month's electric bill got me wondering if I'm wasting a lot of both power and money or if it's so insignificant it's not worth worrying about. To find out, I bought a cool little monitor called the Kill A Watt, Electricity Usage Monitor built by P3 International. It's a handheld meter that plugs into an outlet between the device you want to measure and the wall power. There is a LCD screen and 5 pushbuttons on the front that will tell you line voltage, amps draw, watts and VA power, line frequency, power factor and kilowatt hours. Specified accuracy is 0.2%. Best part is that it costs just under $30.
I used the Kill A Watt to satisfy my curiosity about the power usage of my PC and monitor and had the eye opening results in less than an hour, including some calculations on cost. The machine I'm using is a fairly garden variety Compaq Presario 6000 series running at 1.6 GHz with 480 MB of RAM and and an 80 GB hard drive. The Monitor is a ViewSonic VX900 19" flat panel display.
Now here are the measurements I got using the Kill A Watt P3 power monitor. The PC pulls 1 watt even when turned off. That jumps to 89 watts when it is on and 109 watts during disk accesses. The power goes down to 3 watts when the PC is in standby. The monitor draws 2 watts when turned off, but only 1 watt when on but not getting a signal from the computer. Odd, but it's probably an anomaly of the measurements. When the screen is active, the power draw is 37 watts.
Add these together and you get 3 watts with everything turned off but not unplugged and 4 watts while in standby. That jumps to 146 watts when sitting there quiescent but powered up. Using 10 cents per kilowatt hour as a total electric bill price, which is not untypical and makes the math easy, we can calculate what this computer costs. With the computer system off half the day, it burns about 1 KWH a month or 10 cents worth of power just for being plugged in. If left on active the other half of the day, it pulls an additional 1,752 watts or about 53 KWH per month at a cost of $5.26. That's about $63 a year. If it was on standby and not active that entire half the day, the cost would be only 14 cents a month. But, obviously, that's not realistic. There needs to be an appropriate mix of power levels.
The best compromise is to turn off the computer and monitor for long stretches of time overnight or away from the office. Then set the machine to standby when it is not being used for short periods and hibernate for longer periods. The difference is that hibernate saves your working information to disk but takes longer to come back on. You can make these settings by right clicking on an unused part of the screen, selecting properties, screen saver and then power schemes. You can also get to these settings through the control panel. I've got the monitor set to turn off after 5 minutes and the system to go into standby after 15 minutes and hibernate after 2 hours. Pushing the power button on the PC will also send it into standby immediately if I know I'm going to be gone awhile. You can choose your own settings to match the way you work.
Granted, these measures aren't going to save a fortune, but it's money that would otherwise be going down the drain for no good reason. It's also power draw on the grid that encourages the electric company to think about building more coal fired power plants, belching more greenhouse gases and assuring additional future rate hikes. There is no sacrifice involved here. The computer will automatically shift into a lower power mode anytime it is being ignored and come back to life pretty quickly when needed.
Now consider this micro experience on a macro basis. How about corporations running thousands of PCs, with many of them just sitting there glowing at full power while their users are in endless staff meetings or off having lunch. You can see how 150 Watts become 150 KW pretty easily. That's thousands of dollars a month and tens of thousands of dollars a year. All for nothing of value. Add in the cost of air conditioning to remove the heat generated by those active but unused computers and the price goes even higher. Just remember that Power = Money, even though you may have heard it the other way around.
