LED lighting

LED lighting technology

The LED or Light Emitting Diode is a type of solid state lighting (SSL) and was first proposed in Russia during the 1920s and introduced in America as a practical electronic component in 1962. They were initially used as simple indicator lamps and then in the displays in electronic watches and calculators in the early 1970s.

When a light emitting diode is forward biased (switched on), electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence and the color of the light (corresponding to the energy of the photon) is determined by the energy gap of the semiconductor. An LED is often small in area (less than 1 mm²), and integrated optical components may be used to shape its radiation pattern. LEDs present many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved robustness, smaller size, faster switching, and greater durability and reliability.

Today the LED is being used in a variety of applications from traffic lights to wide screen televisions. LED technology has advanced such that it is now a viable alternative to traditional lighting products offering significant reductions in energy consumption and an increased light life span.

The advantages include:

• High efficiency - LEDs reliably offer 75 lumens or more per watt of output;
• Small size - provides design flexibility, arranged in rows, rings, clusters, or individual points;
• High durability - LEDs, being solid state components, are difficult to damage with external shock, unlike fluorescent and incandescent bulbs which are fragile;
• On/Off time - LEDs light up very quickly, typically our LED lights will achieve full brightness in less than 1 second from switch on;
• Life span - LEDs have a service life of at least 50,000 hours and potentially far in excess of this to 80,000 hours;
• Slow failure - LEDs dim over time, rather than the abrupt burn-out of incandescent bulbs;
• Environmental benefits - unlike fluorescent and most HID technologies, LEDs contain no hazardous mercury or halogen gases making end of life disposal easier;
• No UV or IR – LED’s have virtually no Ultraviolet (UV) or Infrared (IR) emissions unlike more traditional lighting. Prolonged exposure to UV can cause degradation to materials such as fading, cracking or disintegration, and LEDs radiate very little heat in the form of IR that can cause damage to sensitive objects or fabrics.

The table below compares the various lighting technologies available with LED lighting, demonstrating the significant benefits that the adoption of LED lighting can offer.

*The CO2 emission factor for electricity is taken to be 0.544kg/kWh
Example based on a warehouse installation of 50 fixtures operating on an 18hrs/day and 7days/wk. basis with an electricity tariff of 10p/kWh.