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Energy Efficient Lighting – Quality Assessment

The present era is the era for energy conservation. The present era also gives an opportunity to conserve energy, through the newly developed inventions and products. Here, we shall talk exactly how to tap this opportunity in the field of lighting.
When we assess the various options of new lighting products for energy conservation, we should bear in mind not only the percentage of energy saved, but also various other aspects such as:

  • Light intensity
  • CRI (Colour Rendering Index)
  • Economy
  • Reliability / Durability
  • Environmental factors such as Harmonics, Power Factor and EMI/RFI

At present, there are only two proven energy efficient light sources that fulfill the first two criteria of light intensity and CRI. They are T5 and LED. Both T5 and LED have efficiency of around 100 lumen/watt. Both of them also have a high CRI of around 0.85.

Lumen/Watt is the measure of the total light output of the source. Lux is the measure of light intensity incident on a particular point at a particular distance from the source. Lux is directly proportional to Lumen. Lux is also inversely proportional to the square of the distance between the source and the point of measurement. While Lumen can be measured by a special photometric integrator as mentioned in IS 2407, it is the lux that is ultimately useful to the user and it can be measured by a simple lux meter or a chrominance meter.

CRI is the color rendering index of the source. It is the measure of how truly the colors of an object appear to the eye. As it is quite well known, both T5 and LED have good lumen/watt (and thus lux and CRI)

Then what about economy? – The Third Criteria. T5 is quite economic, energy saving & with good CRI. A 28W T5 gives more light output as compared to an ordinary T8 consuming 36W with an electronic ballast & 55W with a copper ballast. Thus, not only can a T5 offer 50% energy saving by a one to one replacement, but also much more light output. A T5 tube light with a parabolic reflector gives double DLOR (downward Light output ratio) as compared to ordinary T8 tube light.

Now, what about LED? Is it economic?
The answer lies in the selection process of the source. LED, being a point source, is able to transmit light in a particular direction with a particular spread that is achieved with the help of its primary lens or an external secondary lens. So LED has the ability to transmit light only on the particular area that needs to be illuminated, greatly reducing the spill over of light that would normally occur with any other light source. This ability results in only a small wattage (Power) required to achieve the desired illumination. 
Because LEDs emit nearly 100 lumen/ watt & because light can be directed towards a particular area, and also because LEDs have a life of more than 50,000 hours, it is understandable that LEDs in the long run are economically viable as compared to other sources such as CFL, halogen, etc
For fulfilling the criteria of durability & good environmental parameters, the electronic circuits used to drive the T5 lamps or the LED lamps, are solely responsible. A well designed constant current driver would lead to a long life of the LED lamps as well as the driver itself. Likewise, a well designed Electronic Ballast with Lamp current Crest Factor < 1.7 & with over voltage cut off circuit would lead to a long life of the T5 lamp as well as the Ballast itself.

The environmental parameters such as Harmonics, Power Factor and EMI/RFI are taken care of in a good Electronic circuit and can be assessed by viewing the supply current waveform in a simple oscilloscope.

ACON energy efficient light fittings made by Suveg Electronics, brings solutions to all the five aspects mentioned above.