It's Illuminating: How LEDs Contribute to Saving Earth's Resources
LED lighting is four times more energy efficient and lasts up to 100 times longer than old-fashioned incandescent lighting.
Our one step this week is Lighting 101: LEDs. Light-emitting diodes (or LEDs) were discovered at Marconi Labs in 1907, but it wasn’t until the 1960s and 1970s that red, orange, yellow, and green LEDs were commercialized. White LEDs were not possible until a small company in Tokushima, Japan, was able to create blue LEDs in 1994, an achievement that earned the inventors a Nobel Prize in Physics twenty years later. “As about one-fourth of world electricity consumption is used for lighting purposes, the LEDs contribute to saving the Earth’s resources,” explained the Royal Swedish Academy of Sciences in making the award. “The LED lamp holds great promise for increasing the quality of life […]: due to low power requirements, it can be powered by cheap local solar power.”
Two That Matter Most
To know how well you are meeting your needs for lighting with energy-efficient LEDs, these two indicators matter most:
How much electricity you use.
How many lighting products you buy each year.
Sustainable Practice: Lighting 101
Using LEDs
Use light-emitting diode (LED) lighting instead of incandescent or fluorescent.
Equipment and Materials
LED lighting
Steps
Understand basic lighting concepts, including lumens, watts, CCT, CRI, incandescent, fluorescent, and LED.
Inspect lighting.
Replace non-LED lighting with LED lighting everywhere except in high-heat locations (such as oven lights).
Properly dispose of any hazardous materials (such as fluorescent and CFL lamps that contain mercury).
Discussion
LED lighting is the most sustainable lighting technology yet invented. Its primary advantages are its efficiency, durability, safety, and flexibility. An LED lamp is more than four times more energy efficient than an incandescent lamp and can last one hundred times longer. Furthermore, unlike fluorescent lamps, LEDs do not contain mercury. LEDs can be designed for affordability or high performance, producing light quality ranging from terrible to terrific.
The primary disadvantage of LED lighting is its complex circuitry and susceptibility to perform poorly or be damaged by problems with AC grid power, such as voltage sags or spikes. Manufacturers can choose among tens of thousands of designs and components, making it difficult for consumers to evaluate an LED’s ability to withstand grid power problems.
One practical strategy for upgrading to LED lighting is to buy samples, keep your receipt, try them, and return the ones you don’t like. Another practical strategy is to understand the technology so you can make wise choices, troubleshoot problems, and answer questions from family and friends.
Key considerations when replacing existing lighting with LEDs are
Fluorescent lighting of all kinds, including compact fluorescent lamps (CFLs), contain mercury, which is hazardous. Have a plan to carefully remove all fluorescent lighting from your property without breaking any lamps, store them in a location marked “Household Hazardous Waste,” and dispose of them at a collection point that accepts items containing mercury. Your local city or town government should be able to provide recommendations if you have questions. If they cannot, contact your state government and let them know what your local government told you.
LED lighting sold through retail channels should be accompanied by a lighting facts label, which allows you to select lighting that meets your needs.
The federal government mandates a lighting facts label to specify the following:
Brightness in lumens.
Power consumption (“energy used”) in watts.
Estimated energy costs in dollars per year, stating the assumptions made about hours per day of use and cost per kilowatt-hour of electricity.
Estimated lifespan in years, stating the assumption made about hours per day of use.
Correlated color temperature in Kelvin, on a scale from 2700 K (“warm”) to 6000 K (“cool”).
Two useful facts are not required on the label but are often provided by manufacturers:
Color rendering index.
Dimmability and controls required to dim.
Light-emitting diodes are devices that send electric current through crystalline solid semiconductor materials to emit specific wavelengths of light. Phosphors are materials that absorb and re-emit light at different wavelengths. Humans perceive combinations of red, green, and blue light as white; the relative intensity of each wavelength determines the shade of white we perceive. So, a white light LED lamp uses a combination of emitters or phosphors to produce a combination of light wavelengths that humans perceive as a shade of white.
Diodes allow electric current to pass in one direction only. An LED powered by a direct current source, such as a battery or a solar panel, produces a steady glow of light. An LED powered by an alternating current source produces a flicker. The North American public electricity grid operates at 60 Hertz alternating current, so if nothing is done to control this noise in the incoming power, an LED will flick on and off 60 times per second. To some people, this is imperceptible; to others, it induces headaches and nausea. Thus, depending on the quality of the power an LED receives, it will produce steady light or flickering light.
To prevent flicker in LED fixtures, a power supply called a “driver” can rectify oscillating 60 Hz AC power to smooth DC power. The better the rectifier in the driver, the smoother the DC power output, and the steadier the LED light.
Besides smoothing AC to DC power, an LED driver also limits the current flow to control how bright the LED glows and ensure that the LED does not burn out. As with any semiconducting electronic device, high heat or power surges tend to cause components in LEDs to fail. Diodes are made from delicate materials that can be damaged by excessive current. Unlike most materials, which naturally gain resistance to electricity the hotter they get, the diodes in LED circuits lose resistance as they heat up. As the LED allows more current to flow, a constant-current driver lowers voltage to maintain a constant current through the circuit. In some designs, a variable resistor is paired with each LED to provide a parallel path for current. As the LED’s resistance decreases, the variable resistor also lowers its resistance. In this circuit design, a constant-voltage LED driver can be used because even when the circuit is supplied a constant voltage, not too much current gets pushed through the LED.
An LED fixture consists of a housing, terminals to allow electric current to flow, a driver to control current, emitters with combinations of diodes and phosphors, and a glass or plastic diffuser to spread light out. For compatibility with older lighting technology, some LED housings are made in the shape of screw-in light bulbs, and others are made in the shape of twist-in tubes. Newer LED housings are simply plastic that hold printed circuit boards. If you open up an LED fixture, you’ll typically find the driver and emitter components soldered to printed circuit boards. This solder may contain lead or may be lead-free, depending on the convenience and priorities of the manufacturer.
For many decades, the predominant lighting technology in homes and organizations was tungsten filament incandescent. In fact, this is why the United States started using 110-volt electricity rather than 100 or 200 volts. When supplied with 110 volts, tungsten filaments glow at a pleasant light level and last for about a thousand hours before burning out.
Incandescent lighting is incredibly inefficient, wasting almost all power as heat rather than light. But it is simple and fault-tolerant. Because tungsten resists the flow of current regardless of direction, both AC and DC power create a steady glow. A glowing hot tungsten filament naturally produces light in a range of wavelengths, which humans perceive as white. Dimming an incandescent lamp is easy: simply add resistance in the circuit to lower the flow of current. If you supply too much current to a filament, it acts like a fuse and vaporizes, stopping the flow of electricity. A glass bulb around the filament prevents hot fragments from burning people and starting fires.
Because incandescent lighting is already glowing hot, it is a good choice for hot locations like inside an oven. For all other locations, especially cool or cold locations like in ceilings, on walls, or inside refrigerators or freezers, LED lighting is far superior, especially if you take steps to improve your power quality.
Definitions
Color Rendering Index (CRI): a 0 to 100 scale that measures how well a light source shows true colors compared to sunlight
Correlated Color Temperature (CCT): a scale of 2700 K to 6000 K that indicates the shade of white produced by a tungsten filament glowing at that temperature, with lower K values being a “warm” glow with more reds as a filament is dimmed and higher K values being a “cool” glow with more blues as a filament reaches maximum temperature
Driver: the power supply in an LED lighting system
Fixture: part of a luminaire that holds a lamp
Fluorescent: a lighting technology that arcs electricity at high voltages across a tube filled with mercury gas
Housing: part of a luminaire that holds the fixture and lamp and allows the luminaire to be attached to a ceiling, wall, or post
Incandescent: a lighting technology that pushes current through a resistor that glows as it heats up
Kelvin: the international scientific standard unit of temperature; you can convert to Celsius by adding 273.15 to each degree K
Kilowatt-hour (kWh): the amount of energy in one kilowatt of power for one hour
Lamp: part of a luminaire that emits light
Light-Emitting Diode (LED): a material that allows electricity to flow in only one direction and emits light when current is flowing; LED lighting is any lighting system that uses light-emitting diodes
Lighting Facts Label: a label that the federal government requires so consumers can compare lighting products
Lumen: a measurement of the brightness of light
Luminaire: a complete lighting system, including a housing, fixture, and lamp
Phosphor: a material that absorbs and re-emits light in different wavelengths
Watt: a unit of power (energy per time); one joule per second
Troubleshooting
LEDs produce too much or not enough light
Check the lumens on the lighting facts label
LEDs flicker
Try another brand or model of LED
Replace the LED driver
Consult with an electrician: it’s likely that the LED driver isn’t smoothing AC power sufficiently
LEDs can’t be dimmed
Make sure the LED is dimmable
Replace the dimmer switch with one that is compatible with LEDs
Consult with an electrician to install a different dimming control
LEDs start strobing
Replace the LED driver
Replace the LED
Consult with an electrician: it’s likely that the capacitors in the rectifier circuit of an LED driver have failed
LEDs burn out in less than ten years
Try another brand of model or LED
Consult with an electrician: it’s likely that the circuit is experiencing power quality problems
LED light looks bad
Check the CCT of the LED
Check the CRI of the LED: higher values are usually better
Strategies and Goals
Energy
Increase energy efficiency
Use energy-efficient lighting
Goods
Buy less
Buy lighting that lasts longer
Buy green
Buy lighting without mercury in it
Milestones
Decrease how much energy you buy
Measure: How much electricity you buy
Method: Energy bills
Time Period: Year
Decrease how many lighting products you buy
Measure: How many lighting products you buy
Method: Logbook
Time Period: Year
Increase your mercury-free lighting ratio
Measure: How many mercury-free and mercury-filled light bulbs you own
Method: Audit
Time Period: Snapshot
Limitations
LEDs don’t work well in high-heat locations.
LEDs are more efficient in direct-current circuits, such as electricity systems found in electric cars and battery-powered off-grid homes, compared to the alternating-current circuits found in most homes connected to the public power grid.
Opportunities
Lighting 102: Protecting Dark Skies
Install outdoor lighting that meets the five DarkSky Responsible Outdoor Lighting principles
Electricity 301: Using Battery Power
Install a battery power system
Improve power quality throughout your home
Install DC circuits for efficiently powering sensitive electronics
Provide emergency power in the event of a grid power failure
References
Keywords
lighting, energy, efficiency, LEDs, incandescent, fluorescent, mercury
One Step This Week from Sustainable Practice is a reader-supported publication. To receive new posts and support this work, become a free or paid subscriber.