LED: the rising star
Energy-efficient light bulbs are not new: the first CFL (compact fluorescent lamp) screw-in replacement for an incandescent bulb was introduced in 1980. CFL is now a mature technology and currently accounts for the bulk of the energy-efficient bulb market, but LED-based products, having been introduced initially in many niche markets such as commercial lights, are now proving more and more popular with consumers. LED-based lighting solutions are built on LED chips and modules.
LED modules are replaceable items made up of LED dies or chips and mechanical and optical components for use in a luminaire (light fitting).
The recent success of LED lighting in the shape of consumer solutions means that the market has been flooded by a large number of manufacturers making unverifiable claims about their products' performance, in particular where LED modules are concerned. Yet, designers and producers of lighting and luminaires need to know how long LED modules will continue to deliver a meaningful percentage of their initial light output over the years.
The lighting industry is driving the process for standardization of performance requirements for LED products. As new products are being introduced rapidly, it needs new standards quickly. Manufacturers claim the standardization of performance requirements is an important first step towards like-for-like comparison of luminaires.
To meet this demand, IEC SC 34A recently published two important performance requirement PAS (Publicly Available Specification) documents: IEC/PAS 62717, LED Modules Performance and IEC/PAS 62722-2-1, LED Luminaires Performance.
In both of these, luminaire manufacturers and certification bodies will find definitions of a set of initial performance criteria plus a description on how they may be measured. This will give guidance when determining product performance.
As Lawrence Barling, chairman of IEC SC 34A, told e-tech (see article in this issue): "The use of a PAS in this area has allowed industry agreed specifications to be quickly developed".
Amongst the many quality criteria to be considered when evaluating manufacturers' claims, the IEC PAS documents list the following:
- Rated input power (expressed in watts); that is, the amount of energy consumed by a luminaire, including its power supply
- Rated luminous flux (expressed in lumens), which corresponds to the light emitted by the luminaire
- LED luminaire efficacy (expressed in lumens per watt), which measures the initial luminous flux of a luminaire divided by its initial input power
- Photometric code, which includes rates for colour temperature, colour rendering and chromaticity
- Rated life of the LED module
Some of these parameters, rated life in particular, are difficult to measure accurately now, as the technology is relatively new and the lifetime of LED products is expected to be much longer than that of other types of lighting system.
The IEC has prepared and published many other safety and performance standards for LED-related control gear, lamps, modules, luminaires and products.
IEC PAS documents occupy central stage
At the recent Strategies in Light (SIL) Europe conference, Kay Rauwerdink, speaking on behalf of CELMA, a body representing European national manufacturers’ associations for luminaires and electrotechnical components for luminaires, stressed the importance of the PAS documents and said the industry needed to move on from “comparing apples and pears” when it comes to commercial products. Instead they should compare apples with apples. CELMA has published a guiding paper on the importance of standardization of performance criteria for LED luminaires, quoting extensively both IEC PAS.
Other international bodies working for the standardization of LED chips, modules and light engines (the combination of LED light modules and driver electronics), have stressed the need for standardization of LED products.
Andy Davies, sales development director of LED assemblies at GE (General Electric) Lighting, stated at SIL Europe 2010 that “2010 was the year of the LED light module, but 2011 will be the year of the standardized light module”, a statement confirmed by events.
One can safely anticipate that 2012 will be the year in which mass marketing of LED lighting solutions started. International Standards, PAS and other documents prepared by TC 34 and its SCs will make this possible.