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.

I have heard from a few reputable sources that $1,000 per KW is a good rule of thumb for establishing budget pricing of lighting inverters (UPS - uninterrupted power supply).

Disclaimer: As always, pricing is subject to change. Additionally, there are other factors that always influence price, including quantity. Typically, the larger the volume, the lower the unit price for the equipment. When using this information, be sure to keep these items in mind.

Update (July 21, 2008) - a recent conversation with a representative from an inverter manufacturer revealed that $2 per watt ($2,000 per KW) is probably a better budget number. The rep also told me the range can vary from $6 per watt for small inverters to $1.50 for large systems.

Osram-Sylvania’s new electrodeless lamps caught my eye. Apparently, they released the product over a year ago, according to a press release issued by OSI.

Electrodeless fluorescent lamps, commonly know as induction lamps, offer longer life over standard fluorescent technology. For more information about this technology, see the Licoda.com article, How Induction Lighting Works.

You can view a product information sheet at the following link: http://www.sylvania.com/content/display.scfx?id=003683538

Following is a review of a LED based product recently brought to my attention. The Tre’o TC and Tre’o TE by Insight is a linear high output LED based application that may provide a nice uniform distribution of light.

The product features an extruded aluminum body and is available in indoor (Tre’o TC - UL listed for dry locations) and outdoor (Tre’o TE - UL listed for wet locations) variations. The only drawback, is the size of the outdoor product. One of the advantages of LED can be the size of the package. The indoor Tre’o is of the same size to many manufacturers of similar products which have a UL wet listing. I have no doubt the TE will stand up to the elements.

Both interior and exterior products are available in 15, 30 and 120 degree distributions and three different output configurations - six, 12 and 15 watts/sq ft. It is unclear through the literature whether Insight is different wattages LED components (same LED spacing on all products), or if they are varying the spacing (further apart, less watts/sq ft). I have seen the 120 degree, 12 watts/sq ft models and they produce a nice uniform wash over the distribution and the light output is impressive. As with most LED products, the actual lumen output (compared to conventional luminaires) is unknown and a comparison between LED and other source technology cannot be made. The Tre’o is manufactured with 2800K, 3200K, 4100K and 5500K color temperatures. The product also offers Red, Green and Blue color schemes with the possibility of 24 bit RGB color changing.

I’m sure this product can be compared similarly to the energy consumption and output of some fluorescent luminaires. Typical for most LED based products, there is a price premium and will make the Tre’o a solution for a select number of applications. Specifically, those requiring longer life/less maintenance or a potentially smaller form factor.

As noted in the article, if you have a high maintenance application that requires long lamp life, then the high initial cost of an induction lamp may be justified for the application.

The basic technology for induction lamps is not particularly new. Essentially, an induction lamp is an electrodeless fluorescent. Without electrodes, the lamp relies on the fundamental principles of electromagnetic induction and gas discharge to create light. The elimination of filaments and electrodes results in a lamp of unmatched life. Lasting 100,000 hours or 25 years, this system can outlast 100 incandescent, five HID, or five typical fluorescent lamp changes.

Based on these well-known principles, light can be generated via a gas discharge through simple magnetism. Electromagnetic transformers, which consist of rings with metal coils, create an electromagnetic field around a glass tube which contains the gas, using a high frequency that is generated by an electronic ballast. The discharge path, induced by the coils, forms a closed loop causing acceleration of free electrons, which collide with mercury atoms and excite the electrons. As the excited electrons from these atoms fall back from this higher energy state to a lower stable level, they emit ultraviolet radiation. The UV radiation created is converted to visible light as it passes through a phosphor coating on the surface of the tube. The unusual shape of an induction lamp maximizes the efficiency of the fields that are generated.

Although it is not breakthrough science, until recently, it has not been so commercially viable. New developments have broken down the barriers of costs and technological setbacks, such as EMC interference, lumen depreciation, ability to dim and a useful range of available wattages. Today, its obvious benefits make it the clear-cut choice for many lighting applications over traditional light sources.

For more information on how inducting lighting works, visit the fluorescent induction lighting section of the electrodeless lamp entry at Wikipedia.com.

Light Emitting Diodes (LED) are certainly the buzzword in lighting. These sources offer somewhat efficient lighting with long lamp life for maintenance and a small form factor for unique applications. What many people don’t realize is that LED are not the ultimate answer in lighting. Currently, LEDs are more efficient than incandescent based sources, but not as efficient at fluorescent or HID technology.

LEDs are diodes. Diodes are used in electrical circuit to restrict the flow of current to one direction. As diodes impede the electricity, they release energy, sometimes in the form of light. Depending on the chemical composition and physical make-up of the diode, certain wavelengths of light are manufactured.

Diodes utilize a semiconductor charged with electrons, which passes electrons through this material when an electrical current is applied. As the electrons pass from the negative charge to the positive charge, energy is given off in the form of visible light.

Because LED do not feature electrodes or filaments light other sources, the life of the product is dramatically increased and great for long life applications.