Authors: Dr Kevin Kelly is head of electrical services engineering, Dublin Institute of Technology and James Thomas Duff, Arup and PhD student, Dublin Institute of Technology
In the first article in this two-part series, we looked at how increased demands for more daylight, linked to improved lighting control, are increasingly leading to more holistic design. As a result, architects, engineers and facilities managers must work more closely to provide a holistic solution.
For people reading commercial lighting publications or attending trade shows, it would seem that there is a single solution for all lighting problems – which is light-emitting diodes (LEDs). It is suggested  that the growth of LEDs has happened for three reasons. The first is the immense quantity of money invested in LED by organisations and the consequent rapid development in their capabilities. The second has been the enthusiasm of regulators who see LEDs as the ultimate replacement for incandescents. The third is fashion. At present, opting for LEDs is considered progressive and enlightened.
The outcome of these factors has been explosive growth in the LED market and, similar to all such markets, it has attracted many suppliers. Some of these have a reputation to uphold, but many do not. As a result, the market is now saturated with LED products of unknown pedigree.
This raises an issue for designers, specifiers and purchasers. How can they distinguish good equipment from bad? Surely lighting research can provide this answer? Sadly, it cannot. As a result, very little guidance is available for the purchaser when selecting LED equipment . Boyce has suggested  that a valuable contribution to the lighting community would be a set of standard, simple questions to ask the LED supplier. Any supplier that is unwilling, or unable, to answer these questions should be treated with caution.
These questions would address some of the major issues associated with LED products. Traditionally, not many standards have been in place to regulate the construction, manufacture, performance and operation of LEDs, but in recent years, this has improved somewhat with the introduction of IESNA LM-79-08 (IES Approved Method for the Electrical and Photometric Measurement of Solid-State Lighting Products)  and IESNA LM-80-08 (IES Approved Method: Measuring Lumen Maintenance of LED Light Sources) .
Both of these test methods allow manufacturers to have their products tested in an independent laboratory, to a standard set of testing procedures. This offers designers, purchasers and specifiers a fair comparison between products. Now that this standard set of test procedures is available, the International Electrotechnical Commission (IEC) has gone one step further and published a Publically Available Standard (PAS) IEC/PAS 62722 Performance requirements – LED luminaires for general lighting . This document suggests the quality criteria that should be used when comparing LED products and also suggests that this information should be published on product datasheets.
The criteria listed include: