When it comes to choosing a light bulb, there are lots of options—but what’s the most energy efficient choice? Not all bulbs are created equal.

Out with the Old


When you picture a light bulb in your head, you’re probably thinking of an incandescent bulb. These bulbs are not energy efficient and most of the bulbs you grew up with don’t meet current energy efficiency standards, which is why they are disappearing from stores. Incandescent bulbs work by using electricity to heat up a metal filament inside the bulb until it’s hot enough to create light. This is why incandescents are so energy inefficient. Ninety percent of the energy goes toward producing heat, while only 10% goes toward creating light. Incandescents use about 25%-80% more energy than energy-efficient light bulbs and burn out 3-25 times faster! Even though incandescents bulbs are inexpensive to purchase, consumers end up paying more in electricity costs. Additionally, since incandescent bulbs emit so much heat, they can be a fire hazard.

Energy Efficient Alternatives


Compact fluorescent lamps, or CFLs, are simply curly versions of long tube fluorescent lights that are common in commercial buildings like grocery stores, hospitals, and schools. Unlike incandescents, CFLs do not use heat to create light, so they are much more energy efficient; they use 75% less energy than traditional incandescents. If every home in America replaced just one incandescent light bulb with a CFL, we would save enough energy every year to light 3 million homes and prevent enough greenhouse gas emissions that it would be like taking 800,000 cars off the road. CFLs also have a lifespan up to ten times longer than incandescents. While CFLs cost slightly more than incandescent bulbs, they pay for themselves in less than nine months due to their energy efficiency and lifespan.

So why isn’t everyone using CFLs? Although they are energy efficient and long-lasting, the early bulbs had some performance issues (poor color, flickering). Today you can be assured of high quality bulbs by looking for the ENERGY STAR label on CFLs. Still, there there is one key drawback to these bulbs. CFLs operate by using a very small amount of mercury, a neurotoxin. However, widespread use of CFL bulbs, rather than incandescents, will actually reduce the amount of mercury released into the atmosphere since the  burning of fossil fuels is one of the biggest contributors to mercury emissions. In the home there is no risk of mercury exposure unless the bulb breaks, but even in this case, with proper clean up CFLs pose very little risk. Also because of the trace amount of mercury, CFLs should always be disposed of properly after they reach the end of their lifespan.


Once reserved for small fixtures and tech devices, light emitting diodes, or LEDs are now available in styles that can replace most incandescent or CFL bulbs. LEDs use electricity to create light, so unlike incandescents and CFLs, they emit very little heat. Since most of the electrical energy they use goes into creating light, LEDs are much more energy efficient than incandescent light bulbs and even CFLs. ENERGY STAR approved LEDs use at least 75% less energy than traditional incandescent bulbs! So why aren’t LEDs the norm?

LEDs typically cost more than incandescents or CFLs. However, Additionally, LEDs last a long time. Most LEDs will work for up to 50,000 hours, about 50 times longer than incandescents and 8-10 times longer than CFLs. Used 8 hours a day, an LED bulb will last 17 years! Even though the upfront cost is higher, LEDs pay for themselves over time, plus they are a more sustainable option for the planet. And as with most technology, prices are expected to drop as more products enter the market.

This graphic illustrates the advantages of LEDs.


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