technology

Smart LED lighting will record the highest growth of IoT consumer applications,
from 6 million units in 2015 to 570 million units by 2020.

~Source: Gartner, 2015

LED Technology

Evolution of light by human being dates back to incandescent light. Today, LED technology has proved to be the most efficient system. A light-emitting diode (LED) is a semiconductor (electrical) device, that restricts current flow in one direction. Semiconductor diodes are comprised of two regions, one is p region (positive charges) and other is n region (negative charges). When voltage is applied, the electrons move across the n region into the p region. During the process of an electron moving through the p-n junction, it releases energy. The dispersion of this energy produces visible light.

LED Lighting Colours

LED Lighting can come in many different colours, the most common of these in household usage lights are Warm White, Neutral White and Cool White. Lighting colours Warm White with a Kelvin rating of 2700K-3300K, Neutral White with a Kelvin ranging from 5500K-6000K, Cool White with a Kelvin rating of 6000K-6500K.

Colour Rendered Index (CRI)

CRI is a measurement technique, to define how well a given object displays the true colours of an object. The general colour rendering index rates colour rendering out of 100(100 being the sunlight). The higher the index, the better the colour rendering and different light sources have different colour rendering characteristics.

CRI <70    CRI >90

Correlated Colour Temperature

Colour temperature of a light source is the temperature of an ideal black-body radiator (solid object with certain properties heated up to point of incandescence) that radiates light of comparable due to that of the light source, and its temperature is expressed in Kelvins. For colours based on black body theory, blue occurs at higher temperatures, while red occurs at lower temperatures. This is the opposite of the cultural associations attributed to colours, in which 'red' is 'hot', and 'blue' is 'cold'.

Benefits of LED Lights

High Efficacy

Efficacy is a measure of how well a light source produces visible light. It is the ratio of luminous flux to power, measured in lumens per watt in the International System of Units (SI). Latest lab data showed efficacy more than 250 lm/W. However, in real lighting fixture we must consider several factors such as control gear performance, luminous flux depreciation with increasing junction temperature, optical losses etc., which reduce the overall system efficacy.

“Efficacy increase over the time for various light sources.”

Environmental Impact

Using LEDs reduce environmental impact in several areas. Longer lamp life means that fewer resources are required for maintenance. They also use no mercury and less phosphorus than fluorescent alternatives. These facts combined with high efficiency make LEDs a smart choice while reducing the footprint on the nature.

Controllability

LEDs can be integrated into the electronic control system which allows for control of color balance and intensity, independent of each other while maintaining color rendering accuracy. This is impossible with traditional light sources. For general illumination, LEDs can dim from 0.1 % to 100 %.

Durability

LEDs are highly rugged. They incorporated no filament or fragile glass bulb that can be damaged due to mechanical vibrations and shocks. LED light fixtures are especially appropriate in applications with strong probability of lamp breakage such as bridges, industrial areas, or stadiums.

Low-temperature operation

Low temperatures present a challenge for fluorescent lamps. At low temperatures, higher voltage is required to start fluorescent lamp, and luminous flux is decreased. In contrast, LED performance is inherently increased at low operating temperatures. This feature predestines LEDs for grocery stores, cold storage facilities, and outdoor application.

No UV emissions/ Health aspects

LEDs emit light with negligible ultraviolet (UV) and very little infrared radiation. Small amount of radiated heat by LEDs makes them appropriate for goods which are sensitive to heat. The lack of UV radiation (with appropriate design of optical part) makes them an attractive also for illumination of delicate objects such as artworks as well as materials subject to UV degradation.

"When LED light is used in delicatessen displays and in places with fresh food, it has been proven to breed significantly less bacteria than their halogen or fluorescent counterparts."

~lightology

LED vs Other Sources of Light

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.

Lamp TypeIncandescent buldHalogen lampMetal halide lampMercury vapor lampLED
Efficacy (lm/W)6-1616-3075-12540-7580-160
Input power: (W)20-6055-10020-2400050-5000.2-100
Hazardous chemical content:noHalogensArgon, MercuryArgon, Mercuryno
Electronics ballast:noIn general noneeded to control the currentneededneeded
CRI:10010070-9540-6065-97
Application:Indoor, outdoorIndoor applications like shops, residentialFloodlight, outdoor, shopsOutdoor applications, streetlights, facadeIndoor, Outdoor
Additional Information:high IR radiationhigh IR radiationHigh UV radiationHigh light pollutionlittle UV and IR radiation
Lifetime : (hours)10001000-30006000-20000400050000
CCT27002700-35003800-70003200-42002700-8000
Dimmableyes
0-100%
yes
0-100%
yes
50-100%
noyes
0.1-100%

Lumens in Lighting

Way back in 1960s, a bulb was measured by its ‘candle power’. One would ask for a 40-candle bulb and be sure to get light equal to 40 candles. Over the years, the smart businessman changed it quietly to 40 Watts. The common man never realised the smooth transition to this word “watt”, and assumed 40 watts was equal to 40 candles. No. It is not. 40 watts consumes 40 watts power, but doesn’t deliver 40 candles of light.

Therefore, it is imperative for us to know the worth of light for the watts burned by bulb. The measure of light is called Lumens.

Lumens measure how much light you are getting from a bulb. More lumens mean it's a brighter light; fewer lumens means it's a dimmer light.

Lumens let you buy the amount of light you want. So, when buying your new bulbs, think lumens, not watts.

The brightness, or lumen levels, of the lights in your home may vary widely, so here's a rule of thumb:

To replace a 100-watt incandescent bulb, look for a bulb that gives you about 1600 lumens. If you want something dimmer, go for less lumens; if you prefer brighter light, look for more lumens.

Replace a 75W bulb with an LED bulb that gives you about 1100 lumens
Replace a 60W bulb with an LED bulb that gives you about 800 lumens
Replace a 40W bulb with an LED bulb that gives you about 450 lumens

“Think Lumens, Not Watts”

Application Areas of LED Lights

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Frequently Asked Questions

Efficacy specifies the amount of Light generated per unit of input power. It is expressed in Lumen/watt. This is analogous to fuel efficiency i.e. Kilometer/Liter(millage) of an automobile. The higher the efficacy the better is the Luminaire or the lamp.
An ideal radiator (black body) absorbs all external electromagnetic radiation and re-emits the radiation. As temperature of a black body increases, it changes its colour from red - yellow-white-blue-white etc. This temperature is used as reference to the colours.
  • A typical incandescent lamp lasts about 1,000 hours.
  • A comparable CFL lasts 8,000 to 10,000 hours.
  • An LED Light Lasts for 50,000 hours or even longer.
A natural phenomenon that occurs in the light sources where the light output decreases over period of time of usage. This reduction in light output is referred to as Lumen depreciation.
Normalized to Incandescent lamp life. Lumen depreciation of different light sources will be as follows.
  • Incandescent-10-15 %
  • CFL- 2%
  • LED-0.6%

The effect of temperature on LED lights is
Operating temperature
Operating temperature of the light is the range of temperature over which the device operates without any malfunction and delivers its rated output.
Effect of temperature raise above ambient when in use
Excess heat directly affects short term and long-term LED performance. The short term (reversible) effects are

  • Colour shift
  • Reduced Light output
  • Long term (irreversible permanent) effects
  • Accelerated lumen depreciation and shortened useful life.
At 25° temperature life of the lamp will be 50,000 hours, whereas at 40° C temperature life of the lamp will be 40,000 hours. This tells us that raise in temperature will result in shortened useful life.
When you shop for LED Lights what we must look for
  • Efficacy. Minimum 100L/watt
  • >CRI
  • Low Operating Temperature
  • Electric Power
  • Warranty
  • Durability
  • Glare free
  • At least 5 year warranty
LED lighting is different from other light sources such as incandescent bulbs and CFLs.
Key differences include the following:
Direction: LEDs Lights emit almost all their light output in the direction, rather than dispersing it in all directions. Whereas CFL Lights emit light in all directions.
Colour Rendering Index: Colour Rendering Index is an index rating commonly used to represent how well a light source reproduces the actual colour of object that it illuminates.
Effe sends emergency alerts to notify you of equipment malfunctions. The Effe team will trouble shoot issues prior to any third-party intervention, in many cases, dramatically reducing truck rolls and maintenance costs. When issues require a technician, Effe integrates seamlessly with your computerized maintenance management system (CMMS) to submit tickets and dispatch technicians.
LED Lights produce nearly 70-80% of heat for unit input power. An increase in the junction temperature of the LED has an adverse effect on the light output. The rise in junction temperature results in decrease of light output from the LED package. This results in:
  • Decrease in light output
  • Colour Shift
  • Lumen Depreciation
Heat produced in LED junction is conducted and dissipated to environment through proper thermal management. Thermal management is done with the help of heat sinks present in LED Lights.
LED lights are expensive compared to other light sources, but it is important to consider operational costs, not just the initial cost, because energy and maintenance savings can yield an attractive return on investment. LED products are typically more expensive on a first-cost basis, but prices continue to fall.
The heat generated by the LED should be effectively removed by conducting to the environment by using copper or Aluminium metal surfaces called Heat sinks. If the heat is not removed they cause LEDs to fail.
The quality of the LED bulb can be judged by the degrees of temperature raise when emitting the required amount of light. The minimum the raise the better is the lamp. Generally, 10 to 15° C rise above ambient is good for Indian conditions.
In Indian conditions ambient temperatures are high. To effectively remove the heat generated by the LEDs large surface areas of heat sinks are required hence bigger size.
The LED lamp should function normally without any problem when the line voltage fluctuates heavily and when high voltage comes in the input line.
As per standard LED bulb should work delivering the required light intensity for at least five years.