A light bulb is a simple, often overlooked factor in most homes' total energy consumption. The Environmental Protection Agency reports that if every household in the United States replaced just one standard incandescent light bulb with an energy-efficient one, the nation would annually save about $600 million in energy costs --- enough to power 3 million homes for a year (see references 1).

Compact Fluorescent Light Bulbs Compact fluorescent light (CFL) bulbs were the first alternative light bulb to become widely available. They are more expensive to purchase than incandescent bulbs, but pay for themselves over the lifetime of the bulb. CFLs come in a wide variety of shapes and brightnesses to suit most household needs. Most people recognize the spiral coil, but CFLs also come in flood, bulb and chandelier shapes (see references 2).

Energy and Cost Savings of CFLs CFLs use about one-fourth the energy of standard incandescent bulbs. This, combined with their longer lifespan, translates into significant cost savings. For example, a CFL bulb has a lifespan of approximately 10,000 hours. During that lifespan, it will use 140 kilowatt hours of electricity. At 20 cents per kilowatt hour, the lifetime electricity cost of a CFL is $28. To compare, an incandescent bulb will only last around 1,200 to 2,500 hours. If measured over the 10,000-hour lifespan of a CFL, incandescent bulbs will use around 600 kilowatt hours of electricity, which will cost $120. The CFL will save $92 and 460 kilowatt hours of energy over its lifespan (see references 3).

Light-Emitting Diode (LED) Bulbs Light-emitting diode, or LED, lights are a newer option for residential lighting. They are significantly more energy-efficient than either incandescent or CFL bulbs. LED technology is nothing new. It has been used for decades in strings of Christmas lights, electronics panels and novelty pens. LED light bulbs are clusters of up to 180 individual LED bulbs encased in a diffuser (see references 2).

Energy and Cost Savings of LEDs The biggest benefit of LED lighting is its lifespan. An LED bulb will last approximately 50,000 hours --- five times longer than a CFL bulb. If the bulb is left on for eight hours per day, it will last over 17 years. During that lifespan, an LED bulb will use 300 kilowatt hours of electricity. At 20 cents per kilowatt hour, the lifetime electricity cost of an LED bulb is $60. To compare, you would need five CFLs to match the 50,000-hour lifespan of an LED. Those five CFLs would use 700 kilowatt hours of electricity, costing $140. The LED bulb saves 400 kilowatt hours of electricity compared to the CFL and 2,700 kilowatt hours compared to the incandescent bulb. This represents a cost savings of $80 over CFL bulbs and $540 over incandescent bulbs (see references 3).

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