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LED Lights: The Energy Game Has Changed

Sustainable Practice
12 min readOct 22, 2023

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by Fred Horch, Principal Advisor, Sustainable Practice.

LED lighting saves 88% of the energy that incandescent light bulbs would consume.

LED lighting is a beacon on the pathway to sustainable energy. Last century, the 60-watt, 75-watt, or 100-watt “incandescent” (glowing hot) light bulbs we could buy could double as electric space heaters — emitting 90% heat and only 10% light — and burned out every year or so. Today we can buy a 12-watt LED light that is equivalent to an old-fashioned 100-watt light bulb — and reasonably expect it to last for a decade or more.

LED lighting is a great way to increase our energy parsimony.

Learning a few facts about LED lighting can help us save a little money and energy. Mastering the knowledge in this expert-level guide to LED lighting empowers us to get the most benefit from this incredible new technology.

Efficient Lighting Required By Law

As of August 1, 2023, the minimum efficiency standard required for most light bulbs is 45 lumens per watt. This effectively bans old-fashioned 60-watt, 75-watt, and 100-watt incandescent light bulbs, which only get 15 lumens per watt — it’s not possible for that type of incandescent lighting technology to triple in efficiency. In December 2022, the US Department of Energy proposed increasing the minimum efficiency standard further to 120 lumens per watt, which would make fluorescent lighting illegal. If the new rule goes into effect, almost all new lighting in the United States would be required to be LED or another highly efficient technology.

Understanding LEDs

Traditional lighting fixtures contain

  • wires to connect to line power (usually 120 volt alternating current),
  • sometimes a ballast or driver to convert line power to the correct voltage for
  • “lampholders” (sockets) that hold
  • “lamps” (devices that produce light, commonly called “light bulbs”) covered by
  • a diffuser or lens, all of which are in
  • a metal or plastic housing.

LED lamps can match the size and shape of conventional bulbs or tubes to fit into existing fixtures or can be much smaller. In some new LED fixtures, the light-producing lamps are small chips permanently attached to a plastic housing.

Light-emitting diodes (LEDs) are solar cells in reverse: electrons flow through, and photons flow out. Producing light this way, compared to heating a tungsten filament to glow or arcing current through mercury vapor in a phosphor-coated tube, is more

  1. Reliable: LED lighting can last twenty years (but actual lifespan may vary).
  2. Efficient: for every watt, an LED lamp will provide five times more light than an incandescent bulb and reduce unwanted waste heat.
  3. Healthy: LED lighting contains very little or no mercury or other toxic materials.
  4. Safe: LEDs can be designed to emit no harmful ultraviolet (UV) light, or for germicidal applications, can emit UV light that kills bacteria and destroys viruses.
  5. Focused: LEDs send light in one direction rather than in all directions.
  6. Flexible: LEDs can rapidly switch off and on without requiring long warm-up or cool-down periods.
  7. Cold Tolerant: LEDs work well (and last longer) in cold conditions.

LED lighting is now affordable; a standard household LED light bulb costs about $2.

Lighting Facts Label

The Federal Trade Commission enforces the Energy Labeling Rule that requires manufacturers to provide information about lighting products in a standard format.

Brightness and cost must appear on the front of a light bulb’s package.
The Lighting Facts label must appear on the side or rear of a light bulb’s package.

Historically, consumers selected light bulbs based on power consumption: a 100-watt light bulb consumes 0.1 kWh of electricity per hour, or to put it in terms of energy parsimony, a 100-watt light bulb could run for 10 hours on one kWh of electricity. Back when most light bulbs used tungsten technology, power consumption was a simple proxy for brightness. The more power the light bulb used, the brighter it was.

LED lighting makes comparisons based on watts misleading. A 12-watt LED light bulb uses 80% less power but is brighter than a 60-watt incandescent light bulb and can run for over 80 hours (almost three and a half days) on one kWh of electricity. The Energy Labeling Rule helps consumers make informed decisions when choosing among light bulbs that use vastly different technologies.

Lifespan (Hours or Years)

The typical failure mode of an incandescent lamp is for the filament to break (the light bulb “burns out”) when the light is turned on. LED arrays tend not to fail like that. Instead, they gradually become dimmer over thousands of hours of use. However, LED lighting systems contain more than just LED arrays: they require additional circuitry and components known as an “LED driver” to provide direct current electricity at low voltage to the LED array.

LED drivers often fail like incandescent lamps: they can “burn out” when the light is turned on. If the LED driver is separate from the LED lamp, the driver can be replaced, and the LED lamp often still works fine. If the LED drive is integrated into the LED lamp, both the driver and the lamp will need to be replaced if the driver fails.

LED Arrays Just Fade Away

By industry standards, an LED light source is considered end of life when it loses 30% of its light, or what is known as the L70 rating. The L70 rating is calculated with data provided by an LED component manufacturer’s LM-80 report and extrapolated using an industry accepted TM-21 calculator.

A common misconception when considering fixture life is only accounting for the L70 rating. More often than not, the point of failure is the driver. Driver life is estimated using MTBF [mean time between failure] or accelerated thermal test data at elevated ambient temperatures which are then extrapolated using Bellcore or Milspec standards.

Fixture lifetime must take into account the lifetimes of both the LEDs and the driver. System construction, along with ambient temperature, figure heavily into fixture lifetime.

Understanding LED component and system lifetime, Eaton

Putting an LED driver in a hot environment, such as above a stovetop or in an enclosed fixture, will dramatically reduce its useful life. Keeping an LED driver and LED array cool, on the other hand, will dramatically extend their useful lives.

Lumens (Brightness)

Light is a mixture of many frequencies of electromagnetic radiation. A lumen is the standard unit for brightness of light. Technically, a lumen measures the power of light as perceived by a typical person. Most humans have three photoreceptors in their eyes: one that responds to blue wavelengths of light (peaking around 470 nanometers), one that responds to green (peaking around 550 nm), and one that responds to red (peaking around 600 nm).

The ratios of wavelengths in the stream of radiation we can perceive determines the colors we see. We are blind to electromagnetic radiation that falls outside the range of our photoreceptors. “Full spectrum” lighting sources (such as incandescent bulbs) emit electromagnetic radiation across the spectrum, most of which we can’t see. LED chipsets can be tuned to emit just the wavelengths that our eyes can perceive. By emitting only light we can see, and not radiation we can’t see, LEDs can be much more efficient at converting electricity to visible light than other technologies.

Color Rendering Index (Light Quality)

Color rendering index is not required to be on the Lighting Facts label but affects how people experience artificial lighting. CRI is a scale from 0 (colors completely distorted) to 100 (colors completely accurate) that measures how accurately colors appear under the light source, as compared to how colors appear under sunlight. Fluorescent lighting CRI is often in the 80s; LEDs can have CRIs in the high 90s.

Kelvin Temperature (Light Appearance)

The first electric lighting worked on two basic principles: first, forcing electric current through a material heats it up; second, many materials glow when hot. In the 1800s, people experimented with different materials as filaments for electric lighting before settling on tungsten, which has the highest melting point of known elements.

The color appearance of light produced by a tungsten filament changes depending on how much electric current is forced through. When a filament is relatively cool, it glows with a “warm” yellow light. Forcing more current through makes the filament hotter, producing a “cooler” white light. When the filament is at maximum temperature, the light is reminiscent of sunlight at high noon. Dimmers for incandescent lights take advantage of this physical principle: reducing the flow of electric current makes light dimmer and yellower.

To help people reproduce the appearance of light that a tungsten filament produces at different temperatures, the correlated color temperature (CCT) scale was developed. The full range goes from 1,000 Kelvin to 10,000 K to represent all the colors that a tungsten filament can produce depending on its temperature. The Lighting Facts Light Appearance scale bar goes from 2600 K (Warm) to 6600 K (Cool).

The temperature of an LED array does not affect the light appearance in the same way as the temperature of a tungsten filament. LEDs produce light using a completely different physical principle, directly converting electrical current to specific wavelengths of photons depending on the materials in each diode. LED lamps that contain a mix of diode types can mimic the color shift that happens when dimming an incandescent light bulb or can match a specific color temperature on the CCT scale.

Replacing Fluorescent Lights

Fluorescent lighting, including every compact fluorescent lamp (CFL):

  1. Contains toxic mercury.
  2. Wastes energy compared to LED lighting.
  3. Fails sooner on average, compared to LED lighting.

We can protect our health and safety, save money, prevent pollution, and improve our energy parsimony by removing and recycling all fluorescent lighting. Recycling facilities accept fluorescent lamps and ballasts to ensure that the mercury and other toxic materials in them are handled safely.

Cleaning Up a Broken Fluorescent Lamp

Fluorescent light bulbs contain toxic mercury sealed within the glass tubing. When a fluorescent bulb breaks, some of this mercury is released. The broken bulb can continue to release mercury vapor until it is cleaned up and removed.

Before Cleanup

  • Have people and pets leave the room.
  • Air out the room for 5–10 minutes by opening a window or door to the outdoor environment.
  • Shut off the central forced air heating/air-conditioning system, if you have one.
  • Collect materials needed to clean up broken bulb:
  • Stiff paper or cardboard;
  • Sticky tape;
  • Damp paper towels or disposable wet wipes (for hard surfaces); and
  • A glass jar with a metal lid or a sealable plastic bag.

During Cleanup

  • DO NOT VACUUM. Vacuuming is not recommended unless broken glass remains after all other cleanup steps have been taken. Vacuuming could spread mercury-containing powder or mercury vapor.
  • Be thorough in collecting broken glass and visible powder. Scoop up glass fragments and powder using stiff paper or cardboard. Use sticky tape, such as duct tape, to pick up any remaining small glass fragments and powder. Place the used tape in the glass jar or plastic bag. See the detailed cleanup instructions for more information, and for differences in cleaning up hard surfaces versus carpeting or rugs.
  • Place cleanup materials in a sealable container.

After Cleanup

  • Promptly place all bulb debris and cleanup materials, including vacuum cleaner bags, outdoors in a trash container or protected area until materials can be disposed of. Avoid leaving any bulb fragments or cleanup materials indoors.
  • Next, check with your local government about disposal requirements in your area, because some localities require fluorescent bulbs (broken or unbroken) be taken to a local recycling center. If there is no such requirement in your area, you can dispose of the materials with your household trash.
  • If practical, continue to air out the room where the bulb was broken and leave the heating/air conditioning system shut off for several hours.

If you have further questions, please call your local poison control center at 1–800–222–1222.

Cleaning Up a Broken CFL, US Environmental Protection Agency

Replacing CFLs

With LEDs widely available and affordable, there is no reason to use CFLs. Compact fluorescent lamps (CFLs) were designed to replace traditional screw-in incandescent light bulbs. The fluorescent tubes in these lamps are very thin and twisted to create a shape that fits the profile of a traditional light bulb. Usually, a ballast is integrated into the base of the CFL.

At the time of their introduction, the risk of mercury poisoning from CFLs was deemed acceptable because most electricity was generated by burning coal, which releases mercury into the air and water. When coal power plants were a major source of electricity, replacing an incandescent lamp with a CFL was a net benefit because the reduction in coal use offset the increased risk of exposure to mercury from broken CFLs. Now relatively little electricity is generated by burning coal and LEDs are much more energy efficient and longer lasting than CFLs.

We can successfully replace CFLs with screw-in LEDs by considering

  1. Profile: make sure the shape of the lamp fits the socket and housing. When shopping online, check the measurements of the lamp (shape, height, width, etc.).
  2. Lumens: make sure the LED will be bright enough.
  3. Color temperature: often, two lamps with the same CCT K rating look slightly yellower or whiter; be prepared to compare different brands of LEDs to find the best match with a CFL.
  4. Color rendering index: most people perceive the light quality of an LED as an improvement over a CFL, but some low-CRI LEDs can make colors appear washed out or food look unappetizing. High CRIs (above 90 CRI) are better, but for sensitive areas, be prepared to compare different brands and models of LEDs.

Big box retail stores (like Home Depot and Lowes) accept unbroken CFLs for recycling. According to Earth911, there is no market for broken CFLs; those should be handled per the EPA guidelines and disposed of at a household hazardous waste community pick-up event or facility.

Replacing Other Fluorescent Lighting

We can replace every type of fluorescent lighting with LED retrofit lamps, retrofit kits, or new LED fixtures. Fixtures with four-foot fluorescent tubes are especially common in old buildings; four types of LED replacements are available for these:

  1. Type A LED tubes have an integrated LED driver in them that can work with some fluorescent ballasts. We can simply swap out fluorescent tubes and see if a Type A LED tube works. If the LED tube does not work, then we need to have an electrician remove the fluorescent ballast from the fixture (or replace the entire fixture). Sometimes we can mix LED and fluorescent tubes in the same fixture; other times, this will cause the ballast to fail.
  2. Type B LED tubes have an integrated LED driver in them that can work with line power (120-volt alternating current). A licensed electrician can remove the fluorescent ballast, rewire the fixture to connect line power to the sockets, and then we can install Type B LED tubes. Warning: fluorescent tubes should never be installed in fixtures that have been modified to supply line power to the sockets.
  3. Type A+B LED tubes have an integrated LED driver in them that can work with both fluorescent ballasts and directly on line power. We can install Type A+B LED tubes either by leaving the fluorescent ballast in place or by removing the ballast and rewiring the fixture as per Type B installations.
  4. Type C LED tubes do not have an LED driver in them. A licensed electrician can remove the fluorescent ballast and replace it with an LED driver. Then only Type C LED tubes will work in the fixture.

In new construction, LED lighting is now installed as standard procedure.

What’s Still Ahead on the Pathway…

Earlier this year, we explored the pathway to sustainable movement; now, we’re exploring the related pathway to sustainable energy. What are the best ways to save, use, and make energy? Stay with us on the journey to sustainability as we take action to have a positive impact on the world.

References and Further Reading

Lighting
Sustainability
Environment
Sustainable Living
Energy Efficiency

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Sustainable Practice
Sustainable Practice

Written by Sustainable Practice

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Sustainable Practice helps you measure and improve environmental sustainability, to meet current needs in ways that protect our ability to meet future needs.

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