New Energy Star specifications for computers and related equipment that go into effect next week should save consumers and businesses more than $1.8 billion (£886 million) in energy costs over the next five years.

In addition, the specifications will prevent greenhouse gas emissions equal to the annual emissions of 2.7 million cars, according to Energy Star, the joint programme of the US Environmental Protection Agency and the US Department of Energy.

Under the new Energy Star 4.0 specifications, computers and related equipment, including desktop and notebook computers, workstations, integrated computers, servers and game consoles that meet Energy Star's specifications will earn the Energy Star label.

That means that such computer equipment will be 65% more efficient than other models because they'll use more energy-efficient internal and external power supplies, according to Energy Star.

If all businesses only purchase energy-efficient computers that meet Energy Star requirements, they will save $1.2 billion over the lifetime of the computers, according to Energy Star.

In addition, if government agencies only purchase computers that meet the new Energy Star requirements, they will save nearly 1.4 billion kilowatt hours and reduce greenhouse gas emissions by 2 billion lbs. each year, Energy Star said.

On average, products that meet the Energy Star requirements use about half as much electricity as other models and automatically go into sleep mode after they have been inactive for a period of time. Computers use 75% less energy when they are in sleep mode and copiers use 40% less energy, according to Energy Star.

Earlier this year, HP, Dell Inc and Lenovo all released products that comply with Energy Star's specifications. Earlier this week, Lenovo announced a new version of its ThinkPad T61 laptop that it said is energy efficient but also its highest-performance notebook computer to date.