Does telecommuting save energy?

As the mercury hovers around 100 this afternoon, my colleague Jim Poniewozik over at Tuned In writes in an e-mail:

So telecommuting is supposed to be much better for the environment, right? But is it on high-energy use days like today? Working at home, I'm not using fuel to commute, but then again the subway is running regardless. And I'm using appliances, ceiling fans and a (small) air conditioner I wouldn't be using otherwise. And it's not like I can get Time Inc. to turn the A/C off in my office while I'm out.

What a coinkydink. I just received a study from Sun Microsystems compiling the results of an internal study to determine how its so-called Open Work flexible work project impacts energy usage. The study measures energy usage by Open Work employees "at work in a Sun office, at work at home, and during commuting to and from a Sun office." By comparing home and work energy use, Sun says, it "sought to determine how the energy load is shifted from company to individual to answer the question: 'Does Open Work really save energy, or just transfer energy cost and load to employees?'"

Here's what it found (bolds mine):

Office equipment energy consumption rate at work office was 2x office equipment energy consumption rate at home. By eliminating commuting, each employee reduces energy used for work by 63KWH/day or 5,400KWh/yr, and save an average of 2.5 weeks of work time (8 hours/day, 5 days/week) commuting.

In other words, each employee who telecommutes in lieu or schlepping into an office saves about an annual vacation's worth of time commuting. That amounts to more than $1,700 in gas and vehicle usage and a staggering 5,400 kilowatts of energy. In case you were wondering, Sun's Open Work platform isn't limited to an elite few: nearly 19,000 Sun employees—56%—around the world work from home or in a mobile office. And in case you weren't wondering, it has nothing to do with open marriages.

Jim adds:

In my defense, I am using the A/C sparingly, and wearing shorts.

Not me. I've locked the central air at 50 degrees up here in my attic office so I can sip hot tea and wear a furry hat. Then I'm going to send my energy bill to my boss.