Compact fluorescent lamps/lightbulbs (CFLs) do not give off as much heat as incandescent bulbs. Incandescent bulbs use about 10-15% of the energy consumed for light, and the remaining energy is given off as heat. A CFL lasts longer, uses less energy, and produces approximately 90% less heat than an incandescent bulb. For more information about lighting comparisons, see: Comparing Incandescent Lighting with Compact Fluorescent Lighting
from the U.S. Department of Energy.