Building Green Homes
Compact Fluorescent Lamps (CFLs)
Halogen Incandescent
Halogen Incandescent light bulbs have a capsule inside that holds a halogen gas around a wire filament which increases efficiency by re-depositing metal vapor on to the filament instead of allowing it to evaporate.[1] These types of light bulbs are available in a variety of shapes and colors, and can be used with dimmers. They only meet the federal minimum of energy efficiency standards.
In a CFL the electric current travels through a tube that contains argon and mercury vapor which generates ultraviolet light, exciting a fluorescent coating on the inside of the tube which then emits visible light. This process can take up to three minutes to complete, making it the light bulb take longer to become fully lit. When a CFL is first turned on it needs more energy, but once fully lit it uses around 75% less energy than incandescent bulbs.[1] CFLs are available in a variety of colors, including warm, less harsh tones than when first introduced. Not all CFLs are dimmable, so make sure to check the packaging if looking for that feature. Since CFLs do contain mercury, they should be properly disposed of.
LED light bulbs use solid state lighting technology. Instead of emitting light from a vacuum or gas, it emits light from a solid piece of matter. In a traditional LED a semiconductor is used to emit light from when electrons move around inside it.[1] LEDs use 25 to 30% less energy and last 8 to 25 times longer than halogen incandescents. LEDs are expensive but they still save money by lasting longer and using less energy. [2]
[1] Julia Layton, “How LED Light Bulbs Work”, 23 July 2009
[2] US DOE, “Lighting Choices to Save You Money”, 5 Nov. 2014
Light Emitting Diodes (LEDs)
Lighting
Traditional incandescent light bulbs give off 90% of its energy as heat. Halogen incandescents, compact fluorescent lamps (CFLs), and light emitting diodes (LEDs) are types of energy efficient lighting units. They use between 25 and 80% less energy and last up to 25 times longer than traditional light bulbs. The initial prices of energy-efficient light bulbs are typically higher, but they cost less to operate and do not need to be replaced as often.
This video from Energy & Environmental News describes in detail how incandescent, compact fluorescent and LED bulbs work and discusses some of their drawbacks.
*Based on 2 hrs/day of usage, an electricity rate of 11 cents per kilowatt-hour, shown in U.S. dollars.
Replacing 15 traditional incandescent light bulbs can save you around $50 a year![1]
[1] US DOE, “How Energy-Efficient Light Bulbs Compare with Traditional Incandescents”, 5 Nov. 2014