According to this handy little booklet (PDF) from the U.S. Department of Energy, 11 percent of a household's energy budget is spent on lighting. And it accounts for 22 percent of all the electricity used in the United States, according to a 2009 Department of Energy study.
A new development from MIT could slash a home's energy budget in half. Researchers Matthew Aldrich and Nan Zhao built a system that's able to monitor available light and adjust it automatically. The setup was made using LEDs, the most efficient form of lights that are commercially available. Unlike compact fluorescent bulbs, LEDs can be adjusted to any level of lighting intensity.
An important component of the light-adjusting system is a control device about the size of a business card that's placed on a work surface. The card contains sensors that measure the intensity of light coming from different fixtures or windows.
The control device then adjusts the lighting accordingly. If plenty of natural light is coming in through the windows, for example, the controller lowers the amount of artificial light.