Sun is an old hand when it comes to telework. The technology company has been expanding its telecommuting ranks through its Open Work program for a decade, and today nearly 19,000 employees (56% of Sun's opulation) work from home or in a flexible office.

With that experience comes plenty of knowledge -- about which jobs are best suited for teleworking, which technologies make it work, and how to train home-based employees and their managers, for example. But there was one question Sun couldn't answer until now: Does teleworking really save energy, or does it just transfer energy consumption and costs to employees?

"We sell servers that are improving the carbon footprint. Can we really say the same thing about how our employees are working? Are we really reducing the carbon footprint of our employees and saving money, or are we merely transferring costs from the company to the employees who work from home?" asks Kristi McGee, senior director for Sun's Open Work services group. "That's really the question we were trying to answer."

The company launched a study to measure how much energy is consumed while working in a Sun office, while working at home, and while commuting to and from a Sun office. It outfitted study participants with P3 International's Kill A Watt meter, a kilowatt-hour monitor that taps into a power supply and measures electricity consumption at a workstation.

By comparing home and work energy use, the company found that office equipment in a Sun office consumed energy at a rate twice that of home office equipment. Study participants averaged approximately 64 watts per hour at home compared with 130 watts per hour at a Sun office.

Employees who eliminated the commute to a Sun office also slashed their carbon footprints, McGee says. Sun found that commuting accounted for more than 98% of each employee's work-related carbon footprint, while powering office equipment made up less than 1.7% of a person's total work-related carbon emissions.

By eliminating commuting 2.5 days per week, an employee reduces the energy used for work by the equivalent of 5,400 kilowatt hours each year.

"Not only did we find that the energy used by working in the office was about twice as much as what was used when working from home, which was a significant difference; but what we found also had a huge impact was the energy consumption used in the commute," McGee says.