Lighting FAQ

Lighting FAQ

What is a compact fluorescent light bulb (CFL) and how does it work?
What is a light emitting diode (LED) and how does it work?
Why should I use CFLs and LEDs?
CFLs and LEDs cost more. Are they worth it?
Where can I install CFLs and LEDs?
Can I use CFLs and LEDs outside?
What is ENERGY STAR?
What is a Lighting Facts Label?
What are the benefits of buying an ENERGY STAR rated fixture?
Do CFLs and LEDs work with dimmers and three-way switches?
How do I choose the best color of a CFL or LED? 
How do I choose the correct CFL or LED wattage?
What is the best bulb choice for the environment?
Do CFLs contain mercury?
How should I clean up a broken CFL? 
Can I recycle my CFLs?
Is there a way to calculate my savings from using CFLs?



What is a compact fluorescent light bulb (CFL) and how does it work?

CFL stands for compact fluorescent lamp (light bulb). CFLs are made up of two parts: a ballast and a gas-filled tube. The CFL ballast drives power to the lamp and regulates the flow of electricity. The electric current passes through the gas-filled tube, creating invisible ultraviolet light that excites the phosphor coating on the inside of the tube and produces visible light. Incandescent technology generates light differently. With an incandescent, the electric current runs through a wire filament and heats the filament until it starts to glow. Incandescent bulbs produce heat, which wastes up to 90% of the energy the bulbs use. back to top

What is a light emitting diode (LED) and how does it work?

LED stands for light emitting diode. LED light bulbs combine several individual small light bulbs, or diodes, that generate light by moving electrons through semiconductor materials. Unlike incandescent bulbs, LEDs do not contain filaments or generate a lot of heat. LEDs last up to 25 times longer than incandescent bulbs and are known for being durable. They can take a lot of jarring and bumping and still function efficiently. Many LEDs are dimmable, so they work well for ambient lighting and almost all lighting situations. back to top


Why should I use CFLs and LEDs?

  • Lighting accounts for up to 20% of residential electricity use and is one of the most cost-effective ways to save energy and reduce your energy bills.
  • Compared to incandescent bulbs, CFLs use 75% less energy and LEDs use 85% less energy. CFLs produce 70% less heat than incandescent bulbs, and LEDs produce less heat than both CFLs and incandescent bulbs. LED light bulbs do not radiate infrared or UV light. Because only about 20% of the heat from an LED is transformed into light, the lamp is cool to the touch at all times.
  • Federal lighting standards require light bulbs to use 25% less energy than previous bulbs. The standards are being phased in from 2012 to 2014 and give consumers new energy-saving choices, including CFLS and LEDs in a range of styles, colors and brightness levels. Read more about the new federal lighting standards. back to top


CFLs and LEDs cost more. Are they worth it?

Over time, energy-saving bulbs cost less to use. Compared to incandescent or halogen bulbs, LEDs last up to 25 times longer and CFLs last up to 10 times longer. For example, during the lifespan of one LED bulb, you would need to buy 25 incandescent bulbs to get the same amount of light. In that time, electricity would cost about $34 for the LED, but $164 for the incandescent.  back to top


Where can I install CFLs and LEDs?

CFLs and LEDs are excellent choices for general ambient lighting. With its medium-screw base, a CFL can be installed in any fixture that uses an incandescent bulb. Specialty CFLs are available to use in a range of fixtures, including chandeliers, bath vanities and track lighting. Some CFLs can be used in closed fixtures and with dimmers. To find out more about what type of CFL to use in a particular fixture, visit our How to Choose page.

LEDs come in a range of shapes and sizes and can be used in all common household fixtures, including. accent lighting and outdoor lighting. Many LEDs can be used with dimmers. To find out more about what type of LED to use, visit our How to Choose page.

Be sure to use a CFL or LED that is specified for your particular use, such as indoor reflectors for high-heat recessed cans or outdoor-rated bulbs manufactured to withstand exterior weather conditions.  back to top

Can I use CFLs and LEDs outside?

Yes, CFLs and LEDs can be used in outdoor fixtures. Choose a bulb that has been manufactured for outdoor use—they are specially designed to withstand the elements.  back to top


What is ENERGY STAR?

EnergyStarLogoColorThe ENERGY STAR program, created in 1992, is jointly administered by the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Energy (DOE). This program created a label that is awarded to energy-efficient products that meet strict specifications. This label makes it easier for the consumer to identify energy-efficient products.  back to top


What is a Lighting Facts Label?

The Lighting Facts Label appears on all lighting products packaging as required by the Federal Trade Commission.  It provides information about a bulb’s brightness, operating costs, bulb life and appearance (color).  back to top 

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What are the benefits of buying an ENERGY STAR rated fixture?

ENERGY STAR rated fixtures undergo extensive third-party testing that ensures you are using a quality product. ENERGY STAR fixtures also have a long lamp life of at least 10,000 hours and a three-year ballast/two-year lamp warranty. These fixtures are tested to meet minimum requirements for power, noise and color quality. They come in various styles to fit any decor and are available in “families” of fixtures to create a uniform look throughout your entire home. Find out more about ENERGY STAR fixtures.  back to top

Do CFLs and LEDs work with dimmer and three-way switches?

Certain CFLs and LEDs are specially designed to work with dimmers and three-way switches. Check the packaging to find out whether the bulb you are choosing has these capabilities.  back to top


How do I choose the best color of a CFL or LED?

CFLs and LEDs come in a wide range of color temperatures, which is listed as "light appearance" on the Lighting Facts label. Color temperatures range from warm to cool and are measure by Kelvin ratings. Bulbs with higher Kelvin ratings produce cooler (more blue) light. Bulbs with lower ratings produce warmer (more yellow) light. Most residential lighting ranges from 2,700K to 3,500K (warm white), but if you want cooler light, you can find CFLs and LEDs that range from 2,700K to 6,500K.

Click here to see our CFL and LED Color Selection Guide.  back to top

How do I choose the correct CFL or LED wattage?

If you’re replacing an incandescent bulb with a CFL or LED, look at the packaging to find the right replacement. Most CFL and LED packaging specifies the equivalent incandescent wattage.

However, today brightness (measured in lumens) is the best way to compare and choose light bulbs. Watts measure only the energy used. To find the brightness, look for the Lighting Facts label on all light bulb packaging.  back to top

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What is the best bulb choice for the environment?

LED and CFL bulbs are great choices for saving energy and minimizing impact on the environment. They produce less heat and virtually all components can be recycled.

If every American home replaced just one light bulb with an ENERGY STAR light bulb, we could save enough energy to light 3 million homes for a year and save about $600 million in annual energy costs. We would also prevent 9 billion pounds of greenhouse gas emissions per year, equivalent to taking about 800,000 cars off the road.  back to top

Do CFLs contain mercury?

Yes, CFLs contain a trace amount of mercury (on average about 5 milligrams). This small amount of mercury—equivalent in size to the tip of a ballpoint pen—is necessary for the bulb to function correctly.

FACT: Using CFLs instead of standard incandescent lights actually results in a net reduction of mercury released. Of U.S. mercury emissions, 87% comes from power generation. The amount of mercury released in generating the power to light an incandescent bulb is greater than the trace amount of mercury in a CFL bulb.  back to top

How should I clean up a broken CFL?

  • Sweep up—don't vacuum—all of the glass fragments and fine particles.
  • Place broken pieces in a sealed plastic bag and wipe the area with a damp paper towel. Put the used towel in the plastic bag as well, and throw the plastic bag away.
  • Open windows to allow the room to ventilate.

Find out more information about the clean-up steps recommended by the EPA if a CFL breaks in your home.  back to top

Can I recycle my CFLs and LEDs?

Yes. Like batteries or any other potentially hazardous household products, CFLs should be properly recycled at the end of their life. Please check with your local solid waste agency or click here for CFL recycling options near you. 

LED light bulbs have an average life expectancy of 50,000 hours and can last up to 25 years. LED bulbs don't contain mercury, so recycling them is easier and safer. Many companies, like Home Depot and IKEA, have on-site recycling programs that accept used bulbs and batteries at stores. You may also be able to return burned out LED light bulbs to the retailer or online company you purchased them. back to top

Is there a way to calculate my savings from using CFLs?

Use National Geographic’s fun Light Bulb Savings Calculator to find out how much money and energy you could save by using CFLs and LEDs.  back to top