1. TITLE: LED LIGHTING
LIGHTING WITH LEDs
Lighting typically accounts for 20% to 30% of total electricity consumption
at residential areas and industrial areas. Use of energy efficient lighting or lamps
leads to reduction in our overall energy costs substantially. An LED is a
semiconductor diode, when it is switched on (in forward bias) electrons
recombine with holes within the depletion region of the semiconductor junction
diode, releasing energy in the form of photons. Optical components and
packaging reflect and shape the radiation pattern of the device resulting in bright
light.
In early stage of LED, these were mostly used for indication such as red,
green, or in signaling. It is only after the development of devices with all RGB
components when triggered in proportional manner to emit white illumination,
LEDs were started being used in lighting. Then evolution of technology, use of
blue semiconductor p-n junction chip with suitable phosphor for getting white light
output brought out the actual higher lumen package LEDs for lighting.
LED emits more lumen per watt (higher efficacy), they are smaller in size,
low power consumption, and have high reliability, and they are resistant to shock
and vibration. Availability of wide range of colours, no UV/IR emissions, zero
carbon emissions, silent operation and LED also help reduce greenhouse gas
emissions. Thus it overcomes the major disadvantages of existing lighting
technologies.
Lacking of standard in product rating, specifications, and product type is
the another big challenge for the upcoming LED lighting industry apart from its
major drawback of high initial cost compare to existing lighting solutions. Bureau
of energy efficiency and Bureau of Indian standards are trying to freeze basic
necessary standard required for this industry with the help of societies such as
ELCOMA, ISLE etc. and the manufacturers of LED device. Evaluation of

2. technical characteristic or so called defined specs varies with the different
manufacturer. Regulation in measurements of such parameters becomes need of
the hour, and these should be followed strictly so that the specified parameters
can be compared for two or three different product of same category.
The importance of luminaire efficacy should be preferred against the LED
efficacy used in the product, since overall lumen output of the system depends
on the various other technical parameter and design of the luminaire as well as
the diffuser, reflector used. “Luminaire efficacy accounts for the getting most of
the lumens generated and directed out of the luminaire. International IESNA
standard LM-79 provides test procedures for photometric measurements for the
luminaire using LEDs as their lighting source.
Performance of LED based luminaire will be tremendously affected by
higher temperature or poor heat dissipation of the luminaire. External heat sink is
used to dissipate heat from the junction, which is often designed into the
Luminaire itself. Application of numerous bonding compound, thermal adhesive
tapes plays a major role in the dissipation of the excess heat from the LED pcb
module to the external heat sink. Selection of such parts basically depends on
the total power rating of system, area on the pcb board, size of luminaire heat
sink and open area which is in contact to the ambient. Measurement of the exact
junction temperature (Tj) with the pre design calculated value gives product
designer the confidence on the design and specified technical parameters.
LED Luminaire can be controlled easily with the various types of dimming
protocols. This Intelligent control on the luminaire makes it suitable solution for
different gamut of lighting. This easiness brought intelligent control application
from the limited up-market to the common man’s home. Architectural, façade,
mood lighting got real feel of lighting using very controlled emitted wavelength
and also precise color temperatures of white emission.