CIO — Reducing power usage and cutting carbon emissions is probably the right thing to do for the future of the planet. But keep this is mind: Green is a powerful marketing term right now and cost-savings promises are part of the marketing pitch. Like all marketing promises, results vary. One example: The amount of money a typical consumer can save by using or powering down energy-efficient computers, printers and the like is often small—in the case of an up-to-date laptop, the energy savings add up to perhaps just $10 a year.

I'm no denier of climate change, but technology users should always be skeptical. Just because a cause seems worthy, accepting conventional wisdom at face value isn't smart. Energy conservation is no exception.

The purely economic benefits of power-saving lighting, heating and air conditioning systems dwarf the savings to be had by buying an "Energy Star PC," or simply turning off your electronic gear when not in use. Unless electricity gets much more expensive than it is—on average, most customers pay about 10 cents a kilowatt hour—those economics won't change.

Even more disillusioning was the recent news that the vaunted Energy Star certification program run jointly by the Department of Energy and the Environmental Protection Agency is deeply flawed. Unlike many government programs, Energy Star resonates in the minds of consumers, and there's no end of advertising and commentary that tells us to look for the familiar blue logo.

[ For more on Green IT, see CIO.com's Green IT Hype vs. The Real Deal and our case study, How Raytheon's IT Department Helps Meet Green Goals. ]

So when you learn that government auditors were able to win Energy Star certification by filing bogus applications for non-existent products made by non-existent companies, who wouldn't feel cynical?

Sleeping Computers and Saving Money

When a laptop or desktop computer is asleep, your work is in active memory, but the hard drives have stopped spinning, the display is dark and the microprocessor is idle. As a result, power use drops sharply.

A fully awake desktop system made in the last year or two uses some 60 watts of power, but consumes just three watts when asleep. Laptops use less power to begin with, perhaps 20 watts, and that drops to about 2 watts when the laptop is asleep, according to Bruce Nordman, a researcher at the Lawrence Berkeley National Laboratory.

Well, that sounds like it should save plenty of cash. But let's do the math.

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