Much of that energy is wasted. A study by Lawrence Berkeley National Laboratory found that 60 percent of all desktop PCs remain fully powered on nights and weekends. “It’s a big, big problem,” says Kumar. “And there aren’t a whole lot of answers.”

The U.S. Environmental Protection Agency’s Energy Star program, which provides power consumption benchmarks for appliances and some electronics, has done some good, says Jonathan Koomey, staff scientist at Lawrence Berkeley. New Energy Star specifications, which take effect July 20, require qualifying computers and related equipment to be 65 percent more efficient than conventional models. Manufacturers have to improve efficiency in all aspects of a computer’s operation, as well as include more efficient internal and external power supplies.

PCs and peripherals given the Energy Star seal are expected to save American households and businesses more than $1.8 billion in energy costs over the next five years and prevent greenhouse gas emissions equal to the annual emissions of 2.7 million cars.

Custom printed products supplier VistaPrint has not given as much attention to desktop energy use as it has its data center. “It’s not one of those costs you think about,” admits director of IT operations Aaron Barnham. Nevertheless, says Barnham’s boss, COO Wendy Cebula, the IT organization has made some energy-conscious changes, including replacing CRT monitors with more expensive, but less power-hungry LCD screens and purchasing laptops instead of desktops for most of VistaPrint’s 700 employees. A typical laptop uses 15 to 25 watts of power, compared with 150 watts for a desktop system with monitor.