In the past year or so, many companies have made their notebooks more environmentally friendly: from HP, who changed the packaging for the notebooks they sell at Wal-Mart—instead of a box packed with Styrofoam, the laptops are sold in padded messenger bags—to using LED-backlit screens, which helps reduce the use of mercury (and increases battery life, to boot).

But one area remains relatively untested: How much power are notebooks using on a daily basis? It stands to reason that the less electricity a notebook consumes, the less fossil fuel is needed to create that energy—and the less you owe the utility company. While it adds up to pennies on the dollar for one individual consumer, when you consider that an estimated 148 million laptops were sold last year alone, those pennies—and carbon emissions—start to add up.

With that in mind, LAPTOP Magazine asked notebook vendors to submit their greenest notebooks; we selected 16, which we subjected to a number of the tests that we regularly use to benchmark notebooks, and leveraged them to determine how much power the laptops consumed during everyday activities.

For more information on our testing strategy and grading methodology here >>

These are the four notebook categories we tested:

• Netbooks: Small secondary systems with 9- or 10-inch screens and low-power, low-cost Intel ATOM processors.
• Ultraportables: Slim, light notebooks which have 12- or 13-inch screens, weigh less than 3 pounds, and usually sport low-power processors.
• All-Purpose Notebooks: Mainstream notebooks with 13- to 15-inch screens, weighing more than 3 pounds.
• Desktop Replacements: Large, powerful notebooks with screens that are 16-inches and larger.