Do you know how much your home office costs? I'm not talking about the price you paid for the equipment (you probably do know that amount). Rather, I mean how much of a financial and environmental burden it is to you and your community on an ongoing basis.

I recently found out, for example, that the computing equipment in my home office last year consumed 803 kilowatt-hours of power and directly resulted in the emission of 889 lbs. of carbon dioxide and other greenhouse gases into the atmosphere. My personal contribution to global warming also included 1.4 lbs. of sulfur dioxide and about half a pound of nitrogen oxide, all byproducts of the power-generation process serving my office, according to the Independent System Operator of New England.

All that energy came with a financial cost as well, of course. Could I save money and help save the planet by reducing my energy use without compromising my business? To answer that question, I set out to eliminate every wasted watt of energy -- and wasted dollar -- I could find in my office setup.

The result was shocking. Based on an audit of my own office's energy use, I estimated that when I started, my equipment added US$112 to my annual electricity bill, or 8.5% of the total for my household. Had I been more careful in the selection, configuration and use of the equipment, I could have saved as much as 80% of that -- and put US$90 back into my pocket.

If that sounds like small change in the grand scheme of things, multiply it by the 36 million home offices in the U.S. that use computer and communications equipment, according to market research company IDC. If all offices in the U.S., both commercial and home, used Energy Star-certified equipment, individuals and businesses would save US$1.8 billion in energy costs, and the resulting reduction in greenhouse emissions would be equivalent to removing 2.7 million cars from the roads, according to the U.S. Environmental Protection Agency.

My biggest savings came from some simple changes. I replaced or eliminated inefficient equipment and changed how I configured and used it. After a few big wins, however, the law of diminishing returns began to take hold. The hardest part was deciding what trade-offs I was willing to make to save ever smaller increments of power.

But I'm getting ahead of myself. I couldn't do anything to make my office more energy efficient without knowing where I already stood. "Measure to find out, experiment to optimize, and keep measuring," advises Amory Lovins, chairman and chief scientist at the energy efficiency think tank Rocky Mountain Institute. I decided to follow that advice by performing an energy audit.

Measuring the problem

Fortunately, an energy audit is something you can do yourself with the help of an inexpensive metering device such as P3 International Corp.'s Kill A Watt meter. That device has a retail price of US$39.99, but I found one for less than US$20 on Amazon.com. Even better, to my surprise, I was able to borrow one from my local library. The Kill A Watt plugs into a power outlet and has its own outlet on the front for attaching the device you want to monitor. Among other things, the device displays power draw in watts and tracks cumulative power consumption over time in kilowatt-hours.

By placing all of my devices on two daisy-chained power strips and plugging one of them into the Kill A Watt, I was able to track power consumption for my equipment as a whole. "Your IT equipment should use an average of just 0.2 watts per square foot if you spec and operate it optimally," says Lovins. Mine wasn't even close.

This wasn't really a surprise: "energy-efficient" is not a term I would have expected to apply to my home office. The 120-square-foot space contained a mish-mash of about a dozen devices spread across twelve feet of desk space:

• A Lenovo and a Dell laptop, each with a docking station
• A 19-in. CRT monitor
• A laser printer and a multifunction ink-jet printer (both long in the tooth
• A network storage device
• A set of powered speakers
• A cell phone and charger
• A two-line phone and a cordless headset
• A cable modem and a wireless router