LED Enlightenment

LEDPEDIA
LED bulbs are energy-efficient and designed to last for many years, but here are a few lesser-known features to consider when weighing a jump to LEDs. If you've heard about residential LED light bulbs, you probably know that they're energy-efficient, last a long time, and are pricier than other light bulb technologies. As you consider your lighting options, here a few things that you might not know about LEDs.

LED Lighting

An LED lamp (or LED light bulb) is a solid-state lamp that uses light-emitting diodes (LEDs) as the source of light. LEDs, or light-emitting diodes, are a form of solid-state lighting that is extremely efficient and long-lasting. While incandescent and fluorescent lights consist of filaments in glass bulbs or bulbs that contain gases, LEDs consist of small capsules or lenses in which tiny chips are placed on heat-conducting material. LED lamps offer long service life and high energy efficiency, but initial costs are higher than those of fluorescent and incandescent lamps. LED lamps can be made interchangeable with other types of lamps. Assemblies of high power light-emitting diodes can be used to replace incandescent or fluorescent lamps. Some LED lamps are directly interchangeable with those of incandescent bulbs.

Basic parts of LED lighting

LED lighting starts with a tiny chip (most commonly about one square millimeter) comprised of layers of semi-conducting material. LED packages may contain just one chip or multiple chips, mounted on heat-conducting material called a heat sink and usually enclosed in a lens. The resulting device, typically around 7 to 9 mm on a side, can be used separately or in arrays. LED devices are mounted on a circuit board, which can be programmed to include lighting controls such as dimming, light sensing and pre-set timing. The circuit board is mounted on another heat sink to manage the heat from all the LEDs in the array. The system is then encased in a lighting fixture, architectural structure, or even a “light bulb” package.

How are LED lighting products different from other lighting, like fluorescent or incandescent?

Conventional light bulbs waste most of their energy as heat. For example, an incandescent bulb gives off 90 percent of its energy as heat, while a compact fluorescent bulb wastes 80 percent as heat. LEDs remain cool.
In addition, since they contain no glass components, they are not vulnerable to vibration or breakage like conventional bulbs. LEDs are thus better suited for use in areas like sports facilities and high-crime locations.
How are LED lighting products different from other lighting, like fluorescent or incandescent?
LEDs emit light in a specific direction, whereas an incandescent or fluorescent bulb emits light — and heat — in all directions. For direct lighting applications LED lighting uses both light and energy more efficiently.

For example, an incandescent or compact fluorescent (CFL) bulb inside of a recessed can will waste about half of the light that it produces, while a recessed down light with LEDs only produces light where it’s needed — in the room below.

Incandescent bulbs create light by passing electricity through a metal filament until it becomes so hot that it glows. Incandescent bulbs release 90% of their energy as heat.

Features of LED lights:

Long Life
The life of a high-power white LED is projected to be from 35,000 to 50,000 hours, compared to 750 to 2,000 hours for an incandescent bulb, 8,000 to 10,000 hours for a compact fluorescent and 20,000 to 30,000 hours for a linear fluorescent bulb. LED lifetimes are rated differently than conventional lights, which go out when the filament breaks.

Energy Efficiency
LEDs are today’s most efficient way of illumination and lighting, with an estimated energy efficiency of 80%-90% when compared to conventional light bulbs .This means that about 80% of the electrical energy is converted to light, while in a CFL 20% is lost and converted into other forms of energy such as heat.
LED s operate at Safety Extra Low Voltages (SELV) — typically 12V or 24V, thereby using less power (watts) per unit of light generated (lumens). LEDs help reduce greenhouse gas emissions from power plants and lower electric bills
Lowers power consumption by over 90 times as compared to incandescent bulbs and 70 times more energy efficient than CFL
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, in a well-designed product; LEDs are basically cool to the touch.
LED lighting, when designed well, can be more efficient, durable, versatile and longer lasting than incandescent and fluorescents lighting.

Ecologically Friendly
LED lights are free of toxic chemicals. Most conventional fluorescent lighting bulbs contain a multitude of materials like e.g mercury that are dangerous for the environment. LED lights contain no toxic materials and are 100% recyclable, and will help you to reduce your carbon footprint by up to a third. A big step toward a greener future.

Durable Quality
LEDs are extremely durable and built with sturdy components that are highly rugged and can withstand even the roughest conditions. Because LED lights are resistant to shock, vibrations and external impacts, they make great outdoor lighting systems for rough conditions and exposure to weather, wind, rain or even external vandalism, traffic related public exposure and construction or manufacturing sites.

Zero UV Emissions
LED illumination produces little infrared light and close to no UV emissions. Because of this, LED lighting is highly suitable not only for goods and materials that are sensitive to heat due to the benefit of little radiated heat emission, but also for illumination of UV sensitive objects or materials such as in museums, art galleries, archeological sites, fire prone zones etc.

Operational in Extremely Cold or Hot Temperatures
LEDs are ideal for operation under cold and low outdoor temperature settings. For fluorescent lamps, low temperatures may affect operation and present a challenge, but LEDs illumination operates well also in cold settings, such as for outdoor winter settings, freezer rooms etc.

Light Dispersement
LED is designed to focus its light and can be directed to a specific location without the use of an external reflector, achieving higher application efficiency than conventional lighting. Well-designed LED illumination systems are able to deliver light more efficiently to the desired location.

Instant Lighting & Frequent Switching
You get the full brightness of an LED bulb when you turn it on, which is an advantage over CFLs in a couple of ways. For starters, you don't need to wait for full light if you're running in and out of a room. But frequent cycling also degrades the life of CFLs, one of the reasons that CFLs in some cases don't last as long as expected.

In contrast, traditional lighting may take several seconds to reach full brightness, and frequent on/off switching does drastically reduce operational life expectancy.

LEDs are cooler.
When you're running fans or an air conditioner this summer, having burning-hot incandescent bulbs just makes it harder to manage the heat. LEDs run much cooler than incandescent bulbs and significantly cooler than CFLs.

That's not to say that heat isn't at all an issue. LED bulbs do get hot but the heat is dissipated by metal heat sinks that wick away the heat from the light source itself.

LEDs don't attract bugs.
"no bugs!" (that is, insects) is one of the reasons to use LEDs. Bugs don't fly toward LEDs is because bugs are attracted to ultraviolet light and at least some LEDs don't give off this type of light.

You may have been trained from an early age to associate the wattage of a bulb with its overall light output or brightness. However, especially with today's bulbs, lumens is the unit of measurement that describes how bright a bulb is.

Lighting lingo.

LUMENS

Forget the days of referring to light bulbs as "40 watt", "60 watt" or "100 watt". The new nomenclature focuses on light output in “lumens”.

Light Output/Lumens: Technically, a lumen is a unit of luminous flux derived by measuring the time rate of flow of light. As a point of reference, a traditional 40-watt incandescent light bulb produces a light output of 500 lumens.

Energy Used in Watts: Different types of light bulbs use vastly different amounts of energy to produce the same lumens, so an important bit of information is the energy used in watts, i.e. how many units of active electric power are used by a particular light bulb.

Lumens Per Watt/Efficacy: This measurement expresses the total light output of a light source divided by the total power input. The higher the efficacy rating of a light bulb, the less it will cost you to use it. Calculating a light bulb's efficacy is a simple mathematical process using the information now required on the front of a light bulb package - lumens divided by energy used in watts equals lumens per watt, or efficacy.

For example, the traditional 40 watt incandescent light bulb that produces 500 lumens has an efficacy of 12.5 (500 lumens = 40 watts = 12.5 lumens per watt). The 450 lumens LED light bulb has an efficacy of 56.25 (450 lumens = 8 watts = 56.25 lumens per watt); and the 450-lumens CFL light bulb has an efficacy of 50 (450 lumens = 9 watts = 50 lumens per watt).

Life Hours: Feel like you're always replacing light bulbs? You'll have more information now that the life hours must be labeled on the front of every light bulb package. The life hours are the rated average life of a light bulb as determined by engineering testing and probability analysis.

For example, a traditional 40watt incandescent, 500 lumens light bulb typically provides 1,000 life hours, whereas a 450 lumens LED typically provides 25,000 life hours, and a 450 lumens CFL typically provides 8,000 life hours.

Color Accuracy/Color Rendering Index: Known as CRI, the color rendering index is a description of the effect of a light source on the color appearance of objects being illuminated. CRI is expressed on a scale of 1-100, with a CRI of 100 being the maximum possible. On a good-better-best scale, a good CRI is 60-79, better CRI is 80-89, and best CRI is 90-100.

For example, incandescent light bulbs typically are 100 CRI (no matter what the light output or lumens rating), while CFL light bulbs typically are 82-88 CRI, and LED light bulbs typically are 65-85 CRI.

Light Color/Correlated Color Temperature: Known as CCT, the correlated color temperature describes the light's appearance in terms of its perceived warmth or coolness. CCT is expressed as a temperature measured on the Kelvin temperature scale, where a low CCT (4,000 Kelvin and lower) indicates a warm light, while a higher CCT (4,000 Kelvin and higher) indicates a cool light. Although it seems counter-intuitive for a higher temperature to correlate with cooler light, it is more understandable when picturing a piece of iron that glows red hot at a lower temperature than when it becomes blue hot; the human eye perceives red as warm and blue as cool.