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Frequently Asked Questions on CFLs

The questions below try to address some common uncertainties have before purchasing CFLs. If you have other questions, please email us at
No! It is true that CFLs contain from 1mg to 5mg of mercury. But the coal used to generate roughly half of electricity also contains mercury. When the coal is burned that mercury goes up into the air we breathe. In fact over the life of a typical CFL the EPA estimates that over three times as much mercury will go into the atmosphere from burning coal compared to using CFLs. When you properly recycle your CFLs the positive impact on the environment will be even greater. So you'll be saving energy, saving money on your electric bill, and cutting down on the amount of mercury in our environment.
Lighting represents as much as 25% of the electricity you use at home. The average home has 40 light sockets and spends $1,900 on electricity. Lighting costs, therefore, average as much as $425. Switching all incandescent lights to compact fluorescent bulbs would save the average household roughly $2-300 annually. Switching the lights you use most often to CFLs will let you capture most of these savings. And you will save energy, reduce your carbon footprint, and drive down your monthly utility bill every year going forward. Of course, if your home is larger your savings could be greater.
Should you wait to stop smoking? No! You can start saving energy and money right away. Replacing an incandescent bulb that you use 8 hours a day and that cost you $0.50 would be paid for in 2-3 weeks. If you wait 6 months until that bulb burns out, you've just wasted lots of energy and lots of money. Plus you can always save the incandescent bulbs as replacements for places where you only use lights for a few minutes at a time. For example, in a closet.
According to ENERGY STAR if every home in America replaced just one incandescent light bulb with a CFL bulb, it would save enough energy to light more than 3 million homes and prevent greenhouse gas emissions equivalent to those of more than 800,000 cars annually. What are you waiting for?
The ENERGY STAR label is given to products that save energy and reduce greenhouse gas production. There are over 50 product categories from computers to lighting. Even buildings can earn an ENERGY STAR rating.
The average home spends $1,900 on electricity. ENERGY STAR products can save 30% or approximately $600 annually with similar savings on greenhouse gases.
No, only some compact fluorescent light bulbs have an ENERGY STAR rating. ENERGY STAR has strict requirements. The criteria ensure that all CFLs earning the ENERGY STAR rating meet minimum lifetime and efficacy requirements as well as maximum product start and warm-up times. Any CFL bulb should provide you with substantial energy savings over incandescent bulbs and last much longer.  The criteria for CFLs have become more stringent as the technology has advanced.  Some bulbs that previously earned the Energy Star rating no longer qualify.
You could start by replacing every bulb in your house with a new compact fluorescent light bulb. This would save the most electricity. A more practical approach for most of us would be to change the lights you use most often. For example, you might change lights in your kitchen, family room, or home office. Outdoor lights often are on for hours each night. Changing outdoor lights from incandescent bulbs to compact fluorescent lights will deliver real savings but they are often overlooked. The more the better for your savings and for the environment.
Dimmable CFL bulbs are available in most styles and wattages. You should use only dimmable CFLs in any socket controlled by a dimming switch. Using a non-dimmable CFL bulb in a dimming socket likely will shorten the life of the bulb, potentially substantially. Once you determine if you need dimmable bulbs, please check to make sure that you select bulbs specifically designated as dimmable. Also, you should know that dimmable CFLs can be lowered to 10-20% of their normal light output. Many incandescent bulbs can be dimmed to 0%. Also, the color temperature for incandescents lowers as the bulb is dimmed. This leads to a warmer light. As CFLs are dimmed their color temperature remains the same meaning that the light will continue to have the same color or ambiance.
Absolutely! Most 3-way CFL bulbs are spirals. There are also 3-way A shaped bulbs and torpedo shaped bulbs. We only offer one 3-way spiral bulb currently but hope to add others in the future. 3-Way bulbs are different from dimmable CFL bulbs.
CFLs are available for all rooms including bathrooms. This includes decorative CFLs such as globe CFLs. However, high humidity may shorten the useful life of your CFLs. To keep humidity down run the exhaust fan during and after showers and baths.
Turning lights off to save energy is always a good idea. However, because turning a CFL on and off frequently can shorten its life and CFLs are more expensive than incandescents, ENERGY STAR recommends that you leave CFL lights on for at least 15 minutes at a time.
Because many outdoor lights are on for many hours each day, replacing incandescent bulbs with CFLs can save significant amounts of energy. Extreme temperatures may affect some bulbs. When it is very, very cold it may take these bulbs longer to come to full brightness. Some bulbs are labeled "weatherproof" and can be exposed to rain.
CFLs can be used with mechanical timers with no significant issues. However, electronic and digital timers can damage CFL bulbs and shorten their life. ENERGY STAR recommends that you review product information for the CFL bulbs to ensure compatibility with timers.
Enclosed fixtures do not allow for air flow to cool the bulbs. Even though CFL bulbs produce much less heat than incandescent bulbs, they can be more sensitive to excess heat. Therefore, you should review the product information provided by MySchoolLights to ensure that you choose appropriate CFLs.
The main difference between compact fluorescent lights and the traditional incandescent lights are that CFLs save up to 70% of the energy used by incandescents. Roughly 95% of the energy used by incandescents is given off as heat rather than light. Compact fluorescent light bulbs roughly triple energy efficiency. They give off less heat and give off the same amount of light as incandescents while using much less electricity. That is why you need "smaller" CFL bulbs based on the number of watts compared to what is needed for an incandescent bulb. For example, a 13 watt CFL is roughly equivalent to a 50 watt incandescent bulb.
Compact fluorescent light bulbs also last much longer than incandescent bulbs. You will buy fewer bulbs using CFLs and will need to climb ladders to change bulbs much less frequently. So you will save on electricity costs AND on replacement bulbs.
LED bulbs last even longer and are more efficient than CFLs. They tend to cost significantly more than CFLs or traditional bulbs today but their cost is likely to come down in the coming years. LEDs are also used in special applications like Christmas lights. plans to offer strings of Christmas lights in the coming holiday season.

Our Buying Guide also provides valuable information on how to maximize energy savings by converting to compact fluorescent lights and LEDs while meeting all of your lighting needs.
Many CFLs will last for 8-10,000 hours of use. This is significantly greater than traditional incandescent bulbs which often last for less than 1,000 hours. You can maximize the life of your compact fluorescent bulbs through simple steps. Do not turn them on and off frequently. This will shorten the life of the bulb. Use dimmable and 3-way CFLs in those types of sockets. And use outdoor CFLs in any sockets outside your home.
Dimmable CFLs last much longer than their incandescent counterparts. However, as with incandescents, dimming compact fluorescent bulbs shortens their life. Still the useful life of dimmable compact fluorescent light bulbs is significantly longer than incandescent bulbs. The useful life runs to 6,000 hours for CFL bulbs versus less than 1,000 hours for dimmable incandescent bulbs.
LED lights last even longer than CFLs. They often last for 50,000 hours of use and sometimes up to 100,000 hours. They are more expensive but save much more than their cost in electricity savings and light bulbs you won't have to buy in the future.
The key measure of light brightness is lumens. One model of light bulbs may be more or less bright than others. For example, with different models of 100W household incandescent bulbs from Westinghouse Lighting the number of lumens ranges from 860 to 1,710. The more lumens the brighter the bulb. The 23W spiral CFL, by comparison, has 1,425 lumens.

When shopping you should consider where you will use the light, how bright you want the light to be (lumens), and what shade of light (warm white to daylight) you would like. Shades of light are discussed next and in our Buying Guide
Just as beauty is in the eye of the beholder, the quality of the light from any light bulb depends on who is using the light, how they are using the light, and how they like it. Some people like clear bulbs in some applications. Other people a softer light.  Different CFL bulbs produce shades of light. The shade is identified by the correlated color temperature (often referred to as "Kelvin"). Lower numbers mean the light has a softer, cooler (more yellowish) color. According to ENERGY STAR most CFLs offer soft or warm white light at 2700K to 3000K. This is comparable to incandescent bulbs. These bulbs work well in most home settings and enhance warm colors.

Higher color temperature lights emit a more white to bluish-white light. The ratings on these CFL light bulbs are 3500K, 4100K, 5000K, and 6500K. These products are usually identified with the terms "bright white," "natural" or "daylight." These colors will enhance cooler colors (blue, green, violet) in your home. ENERGY STAR offers examples showing the difference in light color.

So think about what type of light you would like in each location. Look for higher color temperatures where you would like a bright light. Look for lower color temperatures for other locations.
Compact fluorescent light bulbs use much less energy than incandescent bulbs. The energy used is measured in watts. But light output is measured in lumens. The more lumens the brighter the light. Because CFLs are so much more efficient, they use less energy (watts) to produce the same amount of light (lumens). In general, you will need 1 watt for a CFL bulb for every 4 watts from an incandescent bulb. The table below from the ENERGY STAR site provides a guide to replacing different watt incandescent bulbs with a CFL:

Energy Star Light Output Equivalency Chart

Therefore, if you are replacing a 40 watt incandescent light bulb you will only need a 9 to 13 watt CFL bulb. Remember to evaluate the number of lumens to select the proper bulb for brightness and to consider the color temperature for the proper ambiance.
PAR stands for parabolic aluminized reflector.  These bulbs produce about 4 times the concentrated light of regular bulbs making them especially useful in outdoor spot or flood lights with their weatherproof casings. The number refers to the bulb's diameter times 1/8th inch.  A PAR30 has a diameter of 3.75 inches.  A PAR38 has a diameter of 4.75 inches.
ENERGY STAR recommends that used bulbs should be recycled. They must be handled carefully because the bulbs contain a small amount of mercury. Information on recycling bulbs can be found at   Some retailers, such as Home Depot, recycle unbroken CFL bulbs.

The EPA also provides recycling information for each state. More information regarding mercury in CFLs, including proper disposal options and what to do if a bulb breaks, can be found in this fact sheet:
Information on Proper Disposal of Compact Fluorescent Light Bulbs (CFLs)
Compact fluorescent bulbs contain a small amount of mercury. By comparison, the thermometer in your medicine cabinet has approximately 500 mg of mercury. CFLs have only 2-5 mg of mercury. Still they should be handled carefully. If a bulb breaks it must be handled properly. The risk should be low. The Environmental Protection Agency (EPA) has developed clean-up guidelines that can be performed by the general public.
ENERGY STAR certified CFL bulbs come with at least a 2 year limited warranty covering manufacturing defects for bulbs used in your home. Save your receipts to document date of purchase. Contact the manufacturer's customer service group for a refund or replacement.

ENERGY STAR also monitors early CFL failures. E-mail ENERGY STAR at, include the manufacturer's name and model number. They can also help you track down the manufacturer's contact information.

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