What's the Best Way to Be Earth-Friendly? Meet the Guy with the Answers

By Bob Schildgen, Sierra Club Books. Posted June 16, 2008.

The following is an excerpt from Hey Mr. Green: Sierra Magazine's Answer Guy Tackles Your Toughest Green Living Questions.

Hey Mr. Green,

Should I turn off my computer at night or put it to "sleep"? --Dave in Bozeman, Montana

Unless you have software or network hookups that require your PC to be on constantly, turn that sucker off. The sleep mode cuts energy use by 70 percent, but using the off switch reduces it even more-and turning off the power strip stanches the flow entirely. (Please don't confuse power saving with screen savers; though the latter may feature a heartwarming picture, they do not save energy.) Since computers in the business sector alone waste more than $1 billion worth of electricity a year, it's surprising that more fuss isn't made about these simple steps.

Some people believe that restarting the computer each time you return consumes a significant amount of energy, but it's really not enough to worry about. Think about it, if these devices actually required as much power to boot up as some believed, circuit breakers would be snapping like castanets and you'd be flamenco dancing back and forth to the fuse box instead of sitting there typing out pertinent questions to Mr. Green. It's also rumored that turning a computer off and on repeatedly hasten its demise. This is simply not true. Even if it were, obsolescence would likely kill off your machine first. And when your desktop PC is put to sleep-permanently-consider replacing it with a laptop, which uses a lot less power.

Hey Mr. Green,

I would like to encourage my son-in-law to turn off the lights when he leaves a room. To do that, I would have to show the cost benefit. Can you help? --Ruth in Watertown, Massachusetts

In olden times, a household authority figure would say, "Turn the lights out," and that would be that. But today's contentious whippersnappers apparently need a detailed financial analysis before flipping the switch. Fortunately, the math is on your side. Electricity rates are based on the number of kilowatt-hours consumed (1 kilowatt equals 1,000 watts).

All you have to do to find the daily cost of operating a light bulb is multiply its wattage by the number of hours it burns, then multiply that by the kilowatt-hour (kWh) rate printed on your utility bill and divide the result by 1,000. To summarize: (hours used x watts x rate) / 1,000 = daily cost.

So if a 100-watt bulb burns for ten hours a day, and the power company charges ten cents a kilowatt-hour, it costs a dime a day to keep lit. That's about $3 per month, or $36 per year. Leaving a half dozen bulbs burning would waste more than $200 per year.

If your son-in-law turns off the lights and puts the annual savings into an account that draws 5 percent interest, in ten years he will have about $2,650, a nice little sum he could invest in some booming alternative energy company.

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Bob Schildgen, a.k.a. Mr. Green, is the author of Hey Mr. Green: Sierra Magazine's Answer Guy Tackles Your Toughest Green Living Questions, published by Sierra Club Books. To ask Mr. Green a question, visit www.heymrgreen.com.

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