What is a LED?
A LED, or light emitting diode, is a semiconductor device (diode) capable of emitting light when an electric current is passed through it. It has three components: the chip, the driver and the lens. The chip allows current to flow in one direction, the driver controls the current and the lens helps diffuse the light.
What is solid-state lighting?
Solid-State Lighting (SSL) refers to a type of lighting that utilizes light-emitting diodes (LEDs), organic light-emitting diodes (OLED) or polymer light-emitting diodes (PLED) as sources of illumination rather than electrical filaments or gas.
How are LEDs used?
The two basic types of LEDs are low-brightness, used primarily for electronic devices and holiday lights, and high-brightness, used in general lighting products.
LEDs are available in two formats: as "replacement" bulbs, to be used with existing fixtures, and as fixtures with integrated LED light sources. The integrated LED option is more energy efficient because the fixture is designed specifically to effectively distribute the light output of the LED light source.
Why are LEDs more energy-efficient?
LEDs are more energy-efficient because most of the energy that LEDs consume is used to produce visible light, instead of heat.
LED lighting products are among some of the most efficient lighting products available. Warm white LEDs produce about the same lumens per watt (lm/W) as compact fluorescent lamps (CFLs) and three times as many lm/W as incandescent bulbs, and cool white LEDs produce twice the lm/W as CFLs and six times as many lm/W as incandescent bulbs. Performance of white LEDs continues to improve rapidly.
However, not all LED lighting products are created equal. Low-quality LED lighting products may be no more efficient than incandescent blubs. And even the most efficient LEDs may not perform adequately if used in a poorly-designed luminaire.
Why choose ENERGY STAR qualified LEDs?
ENERGY STAR qualified LED lights consume at least 75% less energy than conventional incandescent lights. Currently there exists ENERGY STAR qualified LED light fixtures, decorative light strings and LED screw-in replacement bulbs that meet, or exceed, high performance criteria.
For an LED product to become ENERGY STAR qualified, it must meet the following performance criteria:
- equal the brightness of other light fixtures
- distribute light well
- maintain consistent light output over its life
- exhibit excellent colour quality
- meet, or surpass, the efficiency of fluorescent lighting
- light up instantly
- demonstrate no flicker when dimmed
- use no power when turned off
How are LED lighting products different from other lighting, like fluorescent or incandescent?
LED lighting is more efficient and has a much longer life than incandescent and fluorescent lighting. LEDs emit light in a unidirectional manner, whereas an incandescent or fluorescent bulb emits light in all directions.
Incandescent bulbs create light by passing electricity through a metal filament until it becomes so hot that it glows.
In a CFL, an electric current is driven through a tube containing gases. The subsequent reaction produces ultraviolet light that gets transformed into visible light by the fluorescent coating (calLED phosphor) on the inside of the tube.
LED lighting products use light-emitting diodes to produce light very efficiently. The movement of electrons through a semiconductor material illuminates the tiny light sources we call LEDs. A small amount of heat is released backwards into a heat sink. LEDs are usually cool to the touch.
How long do LEDs last compared to other lighting products?
Instead of burning out like incandescent bulbs, LEDs will gradually become dimmer over their lifetime. The lighting industry has established that the useful life of a LED ends when only 70% of its initial light output is emitted. The high quality LEDs that are now available on the market can last up to 25,000 hours or more (equivalent to almost 3 years of continuous operation), depending on the quality of the components of the bulb or fixture, and temperature management.
|Light source||Lifetime (hours)|
|Halogen||2,500 – 5,000|
|CFL||8,000 – 10,000|
Which residential applications are best suited to LEDs?
LEDs are most suited to under-cabinet lighting, recessed lighting, portable desk lamps, accent and task lighting, ceiling-mounted lights, cove lighting, and outdoor lighting for porches, steps and pathways. As the technology continues to evolve more applications will become available.
LEDs have also found a niche in the decorative light string market, where they are functional, attractive and cost-competitive with incandescent lights. In fact, LED is the only technology that currently meets the ENERGY STAR specification for decorative light strings.
Are LEDs a viable replacement for inefficient lighting?
LEDs are quickly becoming the most efficient replacement technology for lighting and are being used more frequently in residential applications. Although the initial cost of a LED bulb or fixture is considerably more than the standard technology, its long life and energy savings offer cost savings over the life of the product. Despite current limitations, great strides are being made with this technology. As it evolves, better quality products with a wider variety of applications and at lower costs will be produced.
What are the advantages of LEDs?
LEDs only consume a fraction of electricity used by conventional fixtures. Good quality LEDs are among the most energy-efficient lighting products available. Over time, using LEDs will contribute to significant electricity savings and reduce greenhouse gas (GHG) emissions.
There are many advantages to choosing LED lighting products:
- Compact size and lightweight
- Resistance to breakage and vibrations
- Lifetime unaffected by frequent on-off cycles
- Good performance in cold temperatures
- Do not contain mercury or lead
- Very little infrared radiation or UV rays emitted
- Do not produce intense heat, as with an incandescent source
- Lights up instantly
- Some are dimmable
What are the limitations of LEDs?
LED is an evolving technology, and as such, improvements are constantly being made. The light of a LED is harder to diffuse than that of an incandescent bulb. Currently, LED lighting may not be suitable for every application. For instance, a warmer white ambiance is harder to create with LED technology than cool, bluish lighting. Thus, it may take some time before warmer whites are widely available at a reasonable cost.
How much do LEDs cost?
The cost of LED lighting products varies widely, depending on quality and light output. The cost of good-quality LEDs is still high compared to standard lighting technologies, although prices in some applications are becoming more competitive as production increases.
It is important, however, to evaluate total costs (i.e.: bulb replacement, electricity use, maintenance costs) over the expected life of the LED product. In the end, the LED product is more economical. As the technology evolves, LEDs will become available at more reasonable prices.
What to look for when purchasing LED lighting products
- Look for the ENERGY STAR symbol on the product because it identifies products that meet or exceed high energy-efficiency levels without compromising performance.
- Look for a warranty of at least three years.
- Be sure of the seller’s credibility to support the warranty and exchanges or returns.
- Beware of products sold at exhibitions or fairs, and on Web sites at very low prices.
Do LEDs create heat?
LEDs don't feel hot to the touch like other light sources. The light from LEDs does not create additional heat in a room but LEDs do create some heat that, if not properly managed, can affect the light quantity and quality over time. To properly manage this heat and its potential negative effects on LED performance, manufacturers must incorporate heat sinks in their designs to conduct the heat away from the light source.
What is a heat sink?
A heat sink is a component that transfers the heat generated within a solid material to a fluid medium, such as air or a liquid. Like a cold spoon that warms up in a hot cup of water, the metallic fin-like features commonly found on LED bulbs and fixtures dissipate the heat by transferring it to the surrounding air.
Are LED lighting products dimmable?
Yes, some LED lighting products can be dimmed, but not all. LED bulbs and fixtures must be designed to dim, and may not be compatible with all dimmer controls designed for incandescent lamps. It may be necessary to replace existing dimmer switches with switches that are compatible with the LED lighting product. The packaging and/or accompanying instructions will indicate whether the product is dimmable and which dimmer products are approved for use with it, or the manufacturer can provide the information. As the LED industry grows, fully compatible LED dimmers will become more prevalent.