LICODA

The truth is, from a lighting standpoint, we don’t know the truth. The lighting industry has been pleading for a set of standards to be published which allows light emitting diode (LED) sources to be compared to traditional lighting sources.

Performance data is available for LED sources, but some of the methods of measurement and the technology behind the production of light, potentially skew the analysis in favor of LED products.

Don’t get me wrong, LEDs are a great new lighting technology that raises the bar on source efficiency and allows light to be presented in unique ways. However, it pains me to see this source misrepresented as the end-all, be-all solution for lighting performance.

Most experts will agree that LEDs do have a significant lifespan. But just how significant is it. The life of a traditional light source is determined with 50% of a collective sample fails to product light (burns out). The problem with LEDs is they never really stop producing light. LEDs will continue to degrade and produce less and less light, until output is unusable. But, what constitutes unusable? I have heard reports of LEDs producing 50% of their initial output (amount light generated when first energized) after only one year of operation. These products may continue to produce light, but if at least twice the amount of product will be required for the majority of the systems life, is this being factored into the efficiency equation? Traditional lamp systems feature standardized testing to monitor the output of a lamp over it’s life cycle.

Another measure of performance for light sources is efficacy. Efficacy indicates the amount of light output (lumens) per energy unit consumed (watts) - the more lumens produced per watt, the higher the output performance of the lamp. This measure ensures we are comparing apples to apples when talking about source performance. There have been reports of LEDs having extremely high efficacies but little information about the method used to conduct the test. In some instances, these LEDs only product light for mere instant at the measured efficacy calling into question the practicality of the measurement. Once again, this exemplifies the need for standards of performance for LEDs.

Conversely, LED sources do provide for luminaire designs that tend to allow more initial lamp lumens to leave the luminaire for increased luminaire efficiency. As always, lighting specifiers should evaluate the total efficacy of the lighting system during analysis, before making any decisions.

Until standards are available, manufactures have been encouraging lighting designers to verify first hand, the performance of LED based products. Make sure you don’t get caught in the whirlwind and force your client into a solution simply because it is the hottest topic in the media. Targeted terms like “energy efficient”, “long lasting” and “high performance” can be misleading due to their vague definitions of accuracy. Be sure you know what your getting into before using these terms to establish your design criteria.