LEDs (Light Emitting Diodes) are vastly superior to CFLs, Halogen, and Zenon (Xenon) regarding efficiency, dimming, and lumen output.
An LED is a semiconductor light source; when a light-emitting diode is turned on, electrons have the ability to recombine with electron openings inside the bulb, discharging energy as photons. The ensuing color of the light compares to the vitality of the photon, generating an impact called electroluminescence.
LED lights have been the go-to answer for task lighting for quite a while, however they are now being regularly used as traditional incandescent replacements. Enhanced engineering has introduced more ambient LEDs, and these fixtures are extremely energy-efficient — You can now trade your standard 60-watt incandescent light with a LED fixture that uses only 12.5 watts of energy that lasts a whole lot longer. LED lights utilize just 10-20% of the power required for the equivalent incandescent light, and they last around 50 times longer. Because of their special configuration, LED lights dim flawlessly, radiate scarcely any high temperature, and are cool to the touch.
The intent of this LED lights “101” page is to give a general understanding of the common lighting industry measuring Techniques and Terms.
Accent lighting: Draws attention to special features or enhances the aesthetic qualities of an indoor or outdoor environment.
Ambient: The surrounding light level in a given area. It is also the temperature in which a LED light source is expected to operate in. Referring to light, it is the light given off by the Sun, Moon, other light fixtures nearby or even within the same space.
Ambient lighting: Provides general illumination indoors for daily activities, and outdoors for safety and security.
Amperage: The strength of an electrical current measured in amperes. The higher the amperage number, the higher the ability to place more devices on a circuit that will be driven by that amperage.
Bulb: It is not a LED. A LED light bulb is a finished product that has the LEDs installed, electrical components installed and is ready to be used by the consumer. A LED light bulb is screwed in place, twisted and locked in place, pressed into sockets or contact terminals.
Candela: The unit of luminous intensity. One candela is defined as the luminous intensity of 1/600,000 square meter of projected area of a blackbody radiator operating at the temperature of solidification of Platimum under pressure of 101,325 Newtons per square meter.
Color Rendering Index (CRI): Also CCT or Correlated Color Temperature. It is a measure of the quality of light. A measurement of the amount of color shift that objects undergo when lighted by a light source as compared with the color of those same objects when seen under a reference light source of comparable color temperature. LED lights CRI values generally range from 60(average) to 90(best). High CRI equates to sharper, crisper, more natural colored pictures while at the same time reducing glare.
Color Temperature: A measure of the color of a light source relative to a black body at a particular temperature expressed in degrees Kelvin (K). Incandescent lights have a low color temperature (approximately 2800K) and have a red-yellowish tone; daylight has a high color temperature (approximately 6000K) and appears bluish (the most popular fluorescent light, Cool White, ia rated at 4100K). Lights with color temperatures below 5000K tend to be more yellow/red, lights rated between 5000 and 6000K are viewed as white, while lights above 6000K tend to have a blue cast.
Daylighting: The practice of placing windows or other openings and reflective surfaces so that during the day natural light provides effective internal lighting. Particular attention is given to daylighting while designing a building when the aim is to maximize visual comfort or to reduce energy use. Energy savings can be achieved either from the reduced use of artificial lighting or from passive solar heating or cooling.
Dimmer: The use of dimmers and dimmer devices will reduces the wattage and output of lighting, which helps save energy.
Efficacy: The ratio of light produced to energy consumed. It’s measured as the number of lumens produced divided by the rate of electricity consumption (lumens per watt).
Efficiency: A measure of the luminous efficiency of a radiant flux, expressed in lumens per watt as the quotient of the total luminous flux by the total flux. For daylighting, this is the quotient of visible flux incident on a surface to radiant flux on that surface. For electric sources, this is the quotient of the total luminous flux emitted by the total lamp power input.
Foot-Candle (FC): The unit is defined as the amount of illumination the inside surface of an imaginary 1-foot radius sphere would be receiving if there were a uniform point source of one candela in the exact center of the sphere. Basically, the amount of light that a single candle would provide to a 1ft. radius sphere.
Full Spectrum: A light bulb or lamp that produces a light spectrum that covers the entire range of visible light (400-700nm) without gaps in its spectral output. White LEDs are inherently a full spectrum light source.
Intensity: Is a measure of the time-averaged energy flux or amount of light striking a given area. For bulbs alone this is measured in terms of lumens while for lighting fixtures it is measured in lux (lumens/sq. meter).
Kelvin Color Temperature: A measure of the color of a light source relative to a black body at a particular temperature expressed in degrees Kelvin (K). Incandescent lights have a low color temperature (approximately 2800K) and have a red-yellowish tone; daylight has a high color temperature (approximately 6000K) and appears bluish (the most popular fluorescent light, Cool White, is rated at 4100K). Today, the phosphors used in fluorescent lamps can be blended to provide any desired color temperature in the range from 2800K to 6000K. Lamps with color temperatures below 5000K tend to be more yellow/red, lamps rated between 5000 and 6000K are viewed as white, while lamps above 6000K tend to have a blue cast.
Kilowatt Hour (kWh) Formula: The measure of electrical energy from which electricity billing is determined. For example, a 100-Watt bulb operated for 1000 hours would consume 100 kilowatt hours (100 Watts x 1000 hours = 100 kWh). At a billing rate of $0.10/kWh, this bulb would cost $10.00 (100 kWh x $0.10/kWh) to operate over 1000 hours.
Light Emitting Diode (LED): LED means light emitting diode. LEDs are a solid state device and do not require heating of a filament to create light. Rather, electricity is passed through a chemical compound that is excited and that generates light.
LEDs are not bulbs or lamps in the true sense of the word and application. LEDs require a lot of work to make them ready to be used by the consumer. They need to be placed on a circuit board or other material that will allow electricity to pass through it at a specific voltage and current, and with components required to operate them at specific voltages such as 12vdc, 24vdc or 120vac. They do not come ready to plug into a 12volt or 120 volt power source.
LED Bar: Refers to a solid strip of material on which LED lights have been soldered to, along with resistors and other components that a specific product requires to make them operate at the stated operating voltage. The Bars are usually an enclosed strip of LEDs. Enclosures are plastics, or aluminum, or metal composites with various types of lens/cover plates.
LED Cluster or Array: A group of LED lights set in a square, rectangular or linear pattern, and formatted to be operated at a specific voltage. They will always include two wires called leads. One is positive, the other negative.
LED Drivers: are current control devices that replace the need for resistors. LED Drivers respond to the changing input voltage while maintaining a constant amount of current (output power) to the LED as its electrical properties change with temperature.
LED Lighting: A general term used by those who do not know the specific type or category of LED lights they are after. LED lighting includes LED bulbs and fixtures, flashlights, strips, clusters and other LED light sources.
LED Strip: LED Strips are usually printed circuit boards with LEDs soldered to the board. The strip can be rigid, or flexible and without any enclosure to protect the LED lights and circuit.
Lumen: A unit of light flow or luminous flux. The lumen rating of a lamp is a measure of the total light output of the lamp. The most common measurement of light output (or luminous flux) is the lumen. Light sources are labeled with an output rating in lumens. For example, a R30 65-Watt indoor flood lamp may have a rating of 750 lumens. Similarly, a light fixture’s output can be expressed in lumens. As lamps and fixtures age and become dirty, their lumen output decreases (i.e., lumen depreciation occurs). Most lamp ratings are based on initial lumens (i.e., when lamp is new).
Lumen Maintenance: How well a LED light bulb is able to retain its intensity when compared to new. Typically a high power smd LED bulb will retain 70% of its intensity for 40,000-50,000 hours. That means a good quality LED bulb will run 8 hours a day for 13 years at 70% of its new condition. No other light source can do this.
Luminance: Luminous Flux (light output). This is the quantity of light that leaves the lamp, measured in lumens (lm). Lamps are rated in both initial and mean lumens. Initial lumens indicate how much light is produced once the lamp has stabilized; for fluorescent and high-intensity discharge (HID) lamps, this is typically 100 hours. Mean lumens indicate the average light output over the lamp’s rated life, which reflects the gradual deterioration of performance due to the rigors of continued operation; for fluorescent lamps, this is usually determined at 40% of rated life.
Lux: The metric unit of measure for illuminance of a surface. One lux is equal to one lumen per square meter. The higher the lux reading the more light the lighting fixture is producing over a given area. Known as lumens per square meter. One lux equals 0.0929 footcandles.
Max Rated Temperature:, or Operating Temperature is the ambient temperature where the LED light source is installed at and should be maintained at. In most case that is around 40-50° Celsius. That is comparable to 104° F to 122° F.
MCD: or Millicandela, is used to rank/denote the brightness of an LED. 1000mcd is equal to one Candela. The higher the mcd number, the brighter the light the LED emits.
Operating Life: usually refers to the number of hours a specific type of LED is expected to be operational. With high powered LED lights, that usually means life after it loses 10-15% or more rated output after 1000 or more hours of run time.
Power Supply: and Transformer and Voltage adapter apply to the electrical conversion of 110/120/240vac line power into 12vdc that will then be applied directly to the LED light product. Power Supplies are rated according to the current/amperage load capacity each will handle. It is an electrical or electro-mechanical device and is sometimes referred to as a LED Driver.
SMD/SMT: A type of low profile LED that is surface mounted to a PCB. These type LED lights are very powerful and range in lumen output from 35 up to 170 lumens. With the latest LED technology being applied today, these have shown to have the most promise in delivering light levels and coloring that we are used to having. Those smd LEDs we talk about, use and sell are in the .5 watt, 1 watt, 3 watt and 5 watt power range. When you see 7 watt or 9 watt LED lights, it will contain 1 watt LEDs x 7, or 1 watt LEDs x 9, or 3 watt LEDs x 3.
SSL: means Solid State Lighting. It does not use heating of a thin fragile filament to create light. Rather it uses electrical current passing through a chemical that will get excited and thus emit light.
Voltage: The rate at which energy is drawn from a source that produces a flow of electricity (amperage) in a circuit. The difference in electrical charge between two points in a circuit is expressed as volts.
Volts: The International System unit of electric potential and electromotive force, equal to the difference of electric potential between two points on a conducting wire carrying a constant current of one ampere when the power dissipated between the points is one watt.
Watt: The unit of measuring electrical power. Watts does not relate to the light output level. It defines the rate of energy consumption by an electrical device when it is in operation. The energy cost of operating an electrical device is calculated as its wattage time in hours of use. In single-phase circuits, it is related to volts and amps by the formula: Volts x Amps x Power Factor (PF) = Watts. (Note: For AC circuits, PF must be included).
Watt per LED: It can be confusing when two watt numbers are used in product specifications. For the application to smd high powered LEDs, the 1 watt, 3 watt, 5 watt, etc, refers to the power consumption of that specific LED installed in that product. The watt numbers expressed as light output are a comparison to an incandescent light bulb light output, eg; a 60 watt light output is equal to a 60 watt incandescent light bulb. The Watt Output is equipment measured.
White: White is defined by Kelvin Temperature or Degrees Kelvin. Most will say that a Kelvin Temperature of 6000k plus is white with a bluish tint. And let’s say that 5000k -5500k is daylight/sunlight white. At 4200k-4500k, it is called cool white. At 2800-3300k, it’s warm white, which is the color temperature most incandescent light bulbs emit. From 5500k on down the scale, the color becomes “warmer” due to the dominance of red and yellow hues. In the opposite direction, whites will have cooler colors like blues and green becoming more apparent, thus they are called cool whites.