The most common types of household
lighting are incandescent and fluorescent. The incandescent light,
dating back to Thomas Edison, is the least expensive and most
common, but it also has a short lifespan and is expensive to operate.
Tungsten halogen lights are more energy efficient than ordinary
incandescents but are also costly to use and present safety issues.
Fluorescent lights are three to four times more efficient than
incandescent bulbs, but their harsher glow has traditionally relegated
them to commercial or office settings.
The compact fluorescent bulb (CFL) has revolutionized
people's perceptions of fluorescent light by moving away from
awkward tube fixtures and glare-prone light. If every household
switched from incandescents to CFLs, it would cut power demand
for lighting in half. A 15-watt CFL bulb yields as much light
as a 75-watt incandescent. CFL bulbs certified by the federal
Energy Star program (and guaranteed for a year) are made by GE,
Panasonic, Osram, Sylvania, Philips, MaxLite, and SunPark. CFL
bulbs contain small amounts of mercury, so it's important they
be recycled properly.