A. In short, because they waste energy. Less than 10 percent of the energy used by the bulb produces light; the rest escapes as heat. So it takes a lot of energy to create the incandescent’s warm glow. There are an estimated 4 billion lightbulb sockets in American homes, according to the Department of Energy and more than 3 billion still use the standard incandescent. You can see how all this wasted energy adds up.
The Energy Independence and Security Act of 2007 aims to help the country become more energy independent, in part, by increasing the efficiency of vehicles, buildings, commercial and industrial equipment, and consumer products such as residential dishwashers, washers, dehumidifiers, and lightbulbs. Most screw-in based bulbs are required to use at least 27 percent less energy by 2014. CFLs, LEDs and some halogen bulbs meet the standard, traditional incandescents do not.
So come January 1, the phase out begins with 100-watt incandescent bulbs, when they can no longer be made or imported but can be sold until supplies run out. The 75-watt fades away in 2013, and a year later it’s good-bye to 60- and 40-watt incancescent bulbs. California began its phase out last January, Europe and Australia in 2009. To find the right energy-saving bulbs for your sockets, see our Ratings of CFLs, LEDs and halogen bulbs.