"It's great if people do things strictly for the benefit of the environment. But increasingly, the more resonant message is, 'Look, as competitive entities, we have to do more with less. So why not use less electricity as well?'" says Andrew Fanara, team leader at the EPA's Energy Star program, which promotes more energy-efficient IT infrastructures and policies.

The savings can be significant, says Jeff McNaught, vice president of marketing operations at Wyse Technology Inc. in San Jose. His company supplied the thin clients for the city of Dayton, and he says another customer, a Fortune 100 retailer, reports saving $5.7 million annually in electricity costs by using some 70,000 thin clients instead of PCs.

The University at Buffalo, part of the State University of New York system, has an aggressive program to cut overall energy consumption that is estimated to be saving more than $10 million annually. Some of those savings come from green computing, says Walter Simpson, the energy officer at the UB Green program.

UB figures that each computer uses $100 worth of electricity a year, and that doesn't include the costs to power data centers and servers. There are additional costs associated with keeping server rooms and computer workspaces at the right temperature.

To counteract such energy demands, Simpson encourages UB staffers to turn off computers when they're not needed, and he uses power management software to put employees' monitors in sleep mode when not in use. He also tries to hold the line against wasteful practices. For example, when IT workers wanted the facilities department, which houses UB Green, to keep its several hundred computers on at night to accommodate occasional upgrades, Simpson told them to upgrade during the day or pick a specific night to leave the computers on. "We're setting an example," he says.