What is LED?

LEDs (Light Emitting Diodes) are solid-state semiconductor devices that convert electrical energy directly into light.

A semiconductor chip consists of two parts, one is called P-type semiconductor where holes dominate the region, and the other part is N-type semiconductor where is dominate by electrons. When they are sandwiched together, there is a PN junction in between. When an electric current is applied to the chip through the lead, electrons are pushed across the junction into the P-region. There electrons and holes meet and recombine and then release energy in the form of photons of light. This is why LED can shine. The wavelength (color) of the light depends on the materials forming the PN junction which is the materials use to make the LED chip.

The development of LED can be roughly divided into three stages, which are the advent of red and green LED, and then blue LED, and then the white light LED.

With the advent of the blue LED the combination of RGB LEDs enabled a new application of LED technology in the way of RGB based white illumination. Coupled with more advanced intensity control full spectrum RGB LED projection came to be. The advent of the blue LED technology enabled the application of various phosphors to produce the White LED in 1997. The ultimate aim of LED development is super-bright white light LEDs that can actually replace the conventional light sources which is being realized today.

New Era in Led Lighting Industry

Light Emitting Diode (LED) is a small, technologically advanced device that generates light by passing current through layers of a semi-conductor material housed in a chip. Touted as a new energy-saving light source that will one day replace conventional light source, LED represents the dawning of a new age in the lighting industry. 

Unlike conventional light sources, LEDs are solid-state lighting devices that do not utilize filaments, gas or mercury to produce light, thereby eliminating traditional lighting challenges such as costly energy consumption, troublesome periodic maintenance, unpleasant heat & glare; damaging ultra violet radiations and limited color control.

Worldwide trend towards LED Technology

• US: Regulated LED lighting Applications facilitated by Dept of Energy (DOE). Congress approved USD 100 million to encourage LED adoption from 2008 to 2012.
• Australia: Banned usage of inefficient light source.
• China: 7 LED cities declared.
• European Union : Banning of Incandescent light bulbs starting Year 2010.
• Others: Clinton Initiative include Bangkok, Beijing, Berlin, Bogota, Buenos Aires, Cairo, Caracas, Chicago, Delhi, Dhaka, Hanoi, Hong Kong, Houston, Istanbul, Jakarta, Johannesburg, Karachi, Lagos, Lima, London, Los Angeles, Madrid, Manila, Melbourne, Mexico City, Moscow, Mumbai, New York, Paris, Philadelphia, Rio de Janeiro, Rome, Sao Paulo, Seoul, Shanghai, Sydney, Toronto, Tokyo, & Warsaw

BENEFITS

The inherent features of LED is decidedly the ability of LED to become the best alternative to conventional light sources, and provide a wider range of applications:

Small Size

An LED is essentially a microscopic chip once encapsulated in an epoxy resin are extremely small and lightweight.

Low Power Consumption

LED consume very little power, far less than standard light bulbs leading to greatly reduced energy costs and extremely enhanced global energy savings.

LEDs also require far less energy to manufacture than other light sources, reducing the environmental impact of artificial lighting even further.
Generally a LED is designed to operate at 2 - 3.6V, 0.02-0.03A current which means a LED typically requires no more than 0.1W to operate.

Rugged

LEDs are rugged, solid state devices and are not susceptible to vibration such as with incandescent filament.

Long Lifetime

When operating at specified voltage, current, and within specified environmental conditions, LEDs can enjoy a long life of up to 100,000 hours. A newer way to evaluate LED lifetime has been established and adopted which is based on lumens depreciation over time to determine the Mean Time between Failure (MTBF).

Australian Building Codes Board
http://www.abcb.gov.au/index.cfm?objectid=79094992-6931-11DF-837D001143D4D594

BCA Building Code of Australia
Energy Efficient - Artificial Lighting and Power

Building Code of Australia
Residential Lighting Control

Building Code of Australia
Energy Efficient Provisions