Hot Topic: Light Bulbs

Have you noticed all the hoopla lately about energy efficient light bulbs? Calls for banning Edison’s ubiquitous incandescent bulb have definitely heated up. And at the same time, worries about mercury have caused some people to shy away from energy efficient compact fluorescent lights (CFLs). Even so, they are currently the best choice from an energy, climate-protection, and public-health perspective.

Top Tips

At home

  • Replace most of your incandescents with compact fluorescents. CFLs use 75% less electricity than incandescent bulbs. And good quality CFLs will burn for 6,000 to 10,000 hours compared with 750 hours for an incandescent–so they hardly ever need replacement. This energy efficient light bulb choice comes in different shapes and sizes–from small spirals (or twists) that fit most lamps to larger glass globes that look more like conventional bulbs. Other options include reflector CFLs for recessed and track lights, candelabra-style CFLs, three-way CFLs, and dimmable CFLs.

When shopping, look for

    • Energy Stars. As with any product, not all CFLs are created equal. Always buy Energy Star labeled energy efficient light bulbs. These have to pass the federal government’s criteria for lamp life, light output, energy use, and other performance characteristics.
  • The right wattage. To choose CFLs with the right amount of light, read the product packaging. It will tell you how the bulb’s wattage compares with that of a standard incandescent. For example, an 18- to 25-watt CFL puts out the same amount of light as a 75-watt incandescent.
  • Low mercury. All fluorescent bulbs contain minute quantities of mercury (see “Other Considerations” below). A few lighting manufacturers market “low mercury” bulbs. Since there are no standards or labeling requirements for mercury content, however, it can be difficult to compare energy efficient light bulbs based on this criteria.
  • The right color.Different fluorescent bulbs produce different colors of light. This can vary from brand to brand. The color is indicated in Kelvin (K) and may be printed on the package or on the ballast. The packaging also usually has a user-friendly label like “warm white.” Here’s general guidance:
    • If you want your energy efficient light bulb color to match an incandescent’s warm glow, choose bulbs labeled “warm white” (2,700-2,800 K). These bulbs are more flattering to faces and clothes.
    • For activities like reading or sewing, you might want to choose “cool white” (3,200K to 4,000 K). Higher color temperatures provide better visual contrast.
    • Some CFLs are labeled “daylight“(above 4,000 K). These provide a bright bluish light, like what you’d experience outside on a sunny day.
  • In addition to screw-in bulbs: hardwired CFLs. In some states, energy codes require hard-wired fluorescent lighting in kitchens and bathrooms. All fluorescent lights require a ballast, which contains the electronics. With hardwired CFLs, the bulb is separate and fits into the ballast with a pin base rather than a regular screw base. With this energy efficient light bulb, you don’t need to replace the ballast (which can last 50,000 hours) when you change the bulb (which lasts 10,000 hours). Some hardwired CFL lamps include dimmers or two-way switches.
  • Linear fluorescents, or fluorescent tubes. These energy efficient light bulbs save even more energy than CFLs and can provide excellent-quality general lighting for kitchens and bathrooms, as well as perimeter or cove lighting in living rooms and other rooms. If you buy “high efficiency” or “high efficacy” bulbs with a high CRI (color rendering index–as close to 90 as you can get), you’ll have good light and no flickering. The narrow diameter T8s and T5s are more efficient than the older style T12s but won’t fit in a fixture made for T12s. Dimming ballasts are available for linear fluorescents but you may have to special-order them.

Other Considerations

  • Bulbs labeled “full spectrum” (they may be fluorescent or incandescent) are sometimes touted as healthier than other light bulbs. There’s no truth to this claim. Full-spectrum bulbs do provide good color rendering, which makes them useful for tasks requiring very accurate perception of color and details. But there’s no other reason for paying the hefty premium charged for them.
  • The amount of mercury in a typical CFL is 3 to 5 milligrams, compared with 500 mg in a mercury thermometer and 3,000 mg in old-style thermostats. That’s not great, but it’s important to keep the risk in perspective. Large quantities of mercury enter the atmosphere (and wind up in fish and then in our bodies) when coal is burned to generate electricity. Because fluorescents are so energy efficient, using them results in a significant net decrease of mercury to the environment.
  • When the bulbs burn out (which doesn’t happen often), they should be recycled so the mercury inside the glass tube can be safely recovered. Even fluorescents labeled low-mercury should be recycled, not thrown in the trash. Some CFLs also contain lead in the solder or glass. It’s not a direct hazard to you, but it’s another reason to recycle spent bulbs. Contact your city’s recycling or hazardous waste disposal department or Earth911 for local recycling drop-off sites.
  • Fluorescent bulbs are pretty durable, but if you do break one, you should take some basic precautions. When the bulb breaks, some of the mercury sticks to the glass and some becomes vapor and mixes with the room’s air. Open the windows for ventilation and leave the room for about 15 minutes. When you return, don’t vacuum up the glass–you don’t want to get mercury inside your vacuum. On a hard floor, use damp paper towels to pick up the glass, or on the carpet, use sticky tape. Then put the towels or tape in a sealed plastic bag or sealed jar, and take it to a CFL recycling center. The U.S. Environmental Protection Agency has more details about dealing with broken fluorescent bulbs. How much should you worry if you break a bulb? Environmental Defense’s chief health officer says not much–that the potential exposure from breaking a CFL is like eating a can or two of tuna.


…to your wallet
CFL prices have come way down–they cost as little as 50 cents each at many discount retailers. Each bulb will save $30 or more in electricity costs over its lifetime. Think about how many bulbs you use in your home and how quickly those savings will add up.

Here’s another bonus: CFLs give off very little heat, so they’ll keep your home cooler in the summer and reduce air conditioning costs. Incandescents, on the other hand, are like mini-heaters: 90% of the electricity they use is wasted as heat!

…to the Earth
Replacing incandescents with CFLs significantly reduces greenhouse gases, mercury, and other toxic emissions from electricity generation. If every U.S. home replaced just one light bulb with an Energy-Star-qualified CFL, we would save enough electricity to light more than 3 million homes for a year (that’s up to $600 million in energy costs!). And the reduction in greenhouse gases would be equal to taking 800,000 cars off the road. Imagine the impact if every home replaced five light bulbs!

Common Mistakes

  • Confusing old-style fluorescents with today’s fluorescents. Almost all fluorescent bulbs sold today have electronic ballasts rather than magnetic ballasts. Electronic ballasts shorten start-up time and virtually eliminate the humming and flickering associated with the old design.
  • Ignoring the directions. Always read the CFL package and the warnings printed on the bulb’s ballast. Most cannot be used in lamps with dimming switches or with photocell controls. Some lighting companies do make dimmable CFLs. If you can’t find them at your local store, order them online.
  • Thinking halogens or low-voltage lights will save you energy. Halogens are a type of incandescent bulb that is only slightly more energy efficient than a standard incandescent. They’re nice for spotlighting an architectural feature or accenting artwork but use them sparingly. “Low-voltage” track lights use halogen bulbs–don’t confuse “low-voltage” with “low-energy.”

Getting Started

Not every retailer carries a wide assortment, so you may need to look for specialty CFLs at a lighting store or online. For the best selection of high quality linear fluorescents, consider going to a commercial lighting store. Home improvement stores and even residential lighting stores may not have good-quality products or knowledgeable sales people.

Related Products & Services

Watch this video from GoGreenTube to learn the basics about CFLs.  Then read on for more advice about energy efficient light bulbs from Sierra Club Green Home.


  1. Alex November 3, 2009
  2. greenman April 12, 2010
  3. Mike in NJ August 7, 2010
  4. Ben January 13, 2011
  5. energy-savinglightbulbs November 8, 2011
  6. Humberto February 27, 2013
  7. Cindy May 19, 2013
  8. David K January 22, 2014

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