CFL bulbs are cheaper than LED bulbs, but they cannot be dimmed, and it may take some time after switching them on for them to become fully bright. Similarly, CFL bulbs may not turn on or reach full brightness in very cold climates, making them less suitable for outdoor lighting. LED bulbs last longer and are more energy efficient. While LED bulbs do not contain mercury, making them easier to dispose of than CFLs, they often contain other elements that can be harmful to the environment.
|Fluorescent Bulbs||LED Bulbs|
|Cost||Roughly $6 to $15 for a 4-pack; $2 to $15 per bulb for Energy Star qualified bulbs||$16 to $25 for Energy Star qualified bulbs|
|Longevity||Usually 6,000 to 15,000 hours. Up to 35,000 hours.||50,000 hours or longer|
|How they work||Fluorescent bulbs generate light by sending an electrical discharge through an ionized gas.||Illumination by movement of electrons through semiconductor material|
|Materials used||Argon, mercury vapor, tungsten, barium, strontium and calcium oxides||Semiconducting material doped with impurities to create a p-n junction, free of mercury|
|Energy efficiency||More than incandescent bulbs; less than LED bulbs||Much more than incandescent and fluorescent bulbs|
|Types||Tanning bulbs, growth bulbs, bilirubin bulbs, germicidal bulbs||Applications in aviation, automotive, advertising, and traffic signal lighting|
|Electricity used equal to 60 W incandescent||13-15 watts||6-8 watts|
|Turn on instantly||No - takes time to warm up to full capacity||Yes|
|Temperature sensitivity||Yes - may not work < -10°F or > 120°F||None|
|Affected by switching on/off||Yes - can reduce lifespan||No Effect|
How Do CFLs and LEDs Work?
CFLs generate light by sending an electrical discharge through a tube containing argon and a small amount of mercury vapor. This generates UV light that excites a fluorescent coating or phosphor inside of the tube, resulting in the emission of visible light.
A light-emitting diode (LED) is a semiconductor light source, where illumination is generated with movement of electrons through the semiconductor material. Unlike CFL and incandescent bulbs, which emit light and heat in all directions, an LED only emits light in a specific direction. This directness allows for more efficient light and energy use.
CFL and LED bulbs use up to 80 percent less energy than their incandescent counterparts and can last up to 25 times longer.
The CFL bulb is known to reduce replacement costs and is an energy saver. However, its average life span is much less than that of an LED bulb. Further, CFLs have flickering problems and a shorter life if it’s switched on and off frequently. The switching process typically takes some time to complete, which is why CFLs take longer than other lights to become fully lit. These bulbs also require optimum temperatures to work; they are known to function under capacity when switched on in lower temperatures.
LEDs have a number of advantages over CFLs, including lower power consumption, longer lifetimes, and no toxic mercury use. LEDs also produce smaller amounts of heat than CFLs. Typical LEDs release its heat back into a heat sink, making the LED bulb cool to the touch.
Compared to a 60-watt incandescent light bulb which draws more than $300 worth of electricity per year and provides about 800 lumens of light, both bulbs save significantly more energy. A CFL uses less than 15 watts and costs only about $75 of electricity per year. LED bulbs emit similar output and draw less than 8 watts of power, with annual costs near $30, and last 50,000 hours, possibly more.
The video below discusses the pros and cons of Fluorescent bulbs as compared to LEDs:
Health Issues and Environmental Impact
The CFL bulb in saving energy is beneficial to the environment. However, its containing mercury may also harm the environment. With disposal of the CFL bulbs, its mercury content can evaporate and cause air and water pollution. Mercury is also a neurotoxin that can have a harmful effect on humans, especially infants.
A new study from UC Irvine and UC Davis scientists researched residue from various pulverized multicolored LED lights. Chemical content analysis showed low-intensity red LEDs contained up to eight times the amount of lead allowed under California law. The bulbs were further found to contain nickel, arsenic, copper, and other metals. UC Irvine’s Oladele Ogunseitan said that breaking one bulb and breathing its fumes would not automatically cause anyone harm, but can lead to possible issues for one regularly exposed to another carcinogen.
Because of the longevity and energy efficiency of CFLs and LED bulbs, it will be long before you have to think of disposing them. Even then, in the event a bulb breaks or stops working, there is a specific way to dispose of them.
If you throw CFLs in the trash, they’re more likely to break even before they reach the landfill, posing a threat to the the health of family members as well as the waste management workers, and eventually releasing toxins in the nearest land or water area.
If the CFL's life is done, find an Environmental Protection Agency-approved CFL recycling site.
In case a CFL at home breaks, the EPA recommends:
- All members (including pets) leave the room
- Air out the room for 10-15 minutes
- Shut off the central forced air
- Collect the shards with a stiff paper, tape or a damp paper towel
- Put the pieces in a glass jar with a metal lid, or in a sealable plastic bag
- Take the broken bulb to a recycling site.
Vacuuming broken pieces is not safe, as it can spread mercury-containing powder or vapor through the home.
LED bulbs do not come with the mercury hazard, but they do contain nickel, lead, and even traces of arsenic which can cause significant health hazards when left in a landfill.
Over 95% of an LED bulb is recyclable - simply check with your local waste management company about its collection and recycle policies.
Components of CFL vs LED bulbs
The CFL bulb is typically a spiral-shaped tube made of tungsten and is coated with barium, strontium and calcium oxides and evaporation of organic solvents. The tube’s interior lining is coated with blends of metallic and rare earth phosphor salts, and its interior is filled with various vapors, including argon, krypton, neon or xenon and low pressure mercury vapor. Heat is applied to the tube to fuse the coating to the lamps. CFLs do require amounts of mercury, about 4 mg in each bulb. For comparison, the mercury content of the old mercury thermometer contained over 100 times this amount. However, having any mercury content is still an environmental issue.
LEDs consist of a semiconducting material chip doped with impurities to create a p-n junction. The electrons and holes charge-carriers flow to the junctions from electrodes with different voltages. Photon energy levels are released if an electron meets a hole. Wavelengths of emitted light, and thus its color, depend on the band gap energy of the materials forming the p-n junction. LED materials used have a direct band gap with energies corresponding to near-IR, visible, or near-UV light.
CFL bulb is usually described by power consumption, longevity, color of light emitted, and brightness. The various types of CFL bulbs include:
- Induce artificial tanning
- Grow lamps used to encourage photosynthesis and growth in plants
- Medical treatments with bilirubin and germicidal lamps.
White LED lamps are achieving increasing market share with their high-efficiency, low power requirement. Some applications are flashlights, solar-powered garden or walkway lights, and bicycle lights. For the monochromatic (colored) LED lamp, applications include traffic signal lamps, and holiday light strings. Beginning in 2010, NASA is using LEDs to grow plants. The red and blue wavelengths of the visible light spectrum can be used for photosynthesis, with these colors becoming used more in LED grow light panels.
CFLs and LED bulbs may be priced higher and incandescent bulbs, but they significantly lower household electricity costs in the long run; LED bulbs even more so. The following table details pricing and related costs for the two bulbs:
How to Choose an LED bulb
In this video and related Wall Street Journal article, Michael Hsu says that prices for LED bulbs have reduced drastically from where they were a few years ago, and the bulbs have gotten better. Hsu also offers tips on how to choose the right LED bulb for your home.
History of CFL and LED light bulbs
Although Thomas Edison is credited with inventing the incandescent light bulb, he was the first to pursue commercial use of fluorescent bulbs as well. In 1934, Arthur Compton from General Electric conducted experiments with fluorescent bulbs, leading to GE commercializing the bulbs. In the US by 1951 more light was produced from fluorescent bulbs than from incandescent bulbs. From their introduction in the 1970s, CFL bulbs only in the last two decades have developed a strong market. This is due perhaps to its higher cost, taking longer to achieve full brightness, and environmental concerns over mercury use.
While electroluminescence as a phenomenon was discovered in 1907 by the British experimenter H. J. Round of Marconi Labs, it was not until 1955 that Rubin Braunstein of the Radio Corporation of America reported on infrared emission from gallium arsenide (GaAs) and other semiconductor alloy. At TI in Dallas in 1961, James R. Biard and Gary Pittman found GaAs emitted infrared light when electric current was applied. In 1962, Nick Holonyak, Jr. at GE developed the first true visible-spectrum (red) LED.
From 1962, early LEDs emitted low-intensity red light, but modern versions are now available across the visible, UV, and IR wavelengths, and with higher brightness. The first high-brightness blue LED, based on indium gallium nitride (InGan), was established in 1994 by Shuji Nakamura of Nichia Corporation. In 2012, Osram demonstrated commercial-based high-power InGaN LEDs grown on Silicon substrates.
- In The Dark About Picking A Light Bulb? This FAQ Can Help - All Things Considered, NPR
- The Best LED Bulbs for Vivid, Rich Colors - Wall Street Journal
- Light Bulb Comparison Chart - Design Recycle Inc.
- Ultimate Light Bulb Test: Incandescent vs. Compact Fluorescent vs. LED - Popular Mechanics
- Shining a light on energy-efficient light bulbs (Infographic) - Mother Nature Network
- Wikipedia: LED lamp
- Wikipedia: Light-emitting diode
- Wikipedia: Compact fluorescent lamp
- Five things to consider before buying LED bulbs - CNET
- How LED Light Bulbs Work - HowStuffWorks
- Energy Efficient Lighting - Eartheasy.com
- How to Recycle Energy Efficiet Light Bulbs - Fresh Energy