LED HypeBusting

June 14, 2009 / no comments

Our clients often wonder why we haven’t switched to specifying LED lighting altogether for all our projects, especially when they see the steady stream of glowing LED hype being produced by the popular media. For both interior and exterior projects, we are taking a cautious approach to adopting LED products into our stable of recommended fixtures.

Unfortunately, there is a tremendous disconnect between the promise of general white LED lighting and the reality of the products that are out on the market today. Here are the three biggest problems with LED products today:

  1. Misleading claims about performance
  2. Difficulty in proving actual fixture lifetime claims
  3. Lighting fixtures designed as “disposable” products

The good news: industry standards are finally taking hold that, if adhered to by the manufacturers, prevent the shenanigans and level the playing field. General white LED lighting is beginning to mature to the point of useful, consistent products. The bad news: right now, the landscape is still littered with unproven fixtures and performance claims that run the gamut from realistic to ludicrous.

Let’s break down the problems:

Misleading claims about performance

Numerous manufacturers (out of questionable ethics or outright ignorance) have commonly used two ways to significantly cheat output claims:

Firstly, raw LED chips are rated at room temperature in perfect laboratory conditions. LED fixtures need to be rated at a stabilized, real world operating temperature. When LED chips are put into fixtures and run for a period of time, they generate a lot of heat, which means they run significantly less efficiently then their laboratory output ratings. You need to ensure that manufacturers are giving you real world performance numbers, not just the raw LED output.

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Second, cool-white LEDs have significantly higher efficiency then warm-white LEDs. Many manufacturers highlight the cool-white output ratings, but try to sell you the nice, incandescent-looking warm-white products. Be sure to know what the efficiency “hit” is with the warm-white output.

Added together, the impact of heat management and color temperature selection can easily mean you are getting half as much light as the specifications claim.

Difficulty in proving actual fixture lifetime claims

As mentioned above, heat is the enemy of LEDs. Good fixture design carefully mates LEDs to large, well-designed metal heatsinks to dissipate the waste heat created by the actual LED chips.

Lifetime predictions are gauged by the temperature at which the heatsink maintains the LEDs. Hopefully, all the other critical components around the LEDs are rated to last just as long as the LEDs themselves. Hopefully!

Here’s the problem: most of the lifetime claims are predicted lifetimes for just-released products with few, if any, real world installations. Manufacturers are trying to launch LED products so fast that they are essentially using their customers as lab rats to prove their products. Do you want to be the lab rat?

Lighting fixtures designed as “disposable” products

Traditional lighting fixtures are relatively easy to make: take a standardized lamp, a standardized socket, a standardized ballast, and throw them in some sheet metal. Presto, you have a product with highly predictable performance.

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LED fixtures, on the other hand, are “finicky fillies.” They require very careful engineering to ensure that the waste heat properly flows from the LED chip, through the circuit board, across the “air gap” to the heatsink, and that the heatsink is sized and shaped properly to radiate/convect the heat to the air around the fixture. Because they are so refined, with such tight operating tolerances, engineers are loath to design LED fixtures with modular, swappable components. Plus, it costs money to make a well-designed, repairable fixture; it is a lot cheaper to make a non-repairable product, and have a sales guy sidestep the whole maintenance problem by simply saying “don’t worry… it practically lasts forever!”

Not all doom and gloom…

In summary, the single biggest challenge with LEDs is heat. Contrary to misleading claims in the media, LEDs generate significant waste heat. It drastically reduces the operating efficiency and reduces the overall lifetime of LED chips. LED fixtures need to be carefully designed with generous, efficient heatsinks to dissipate the heat and maintain claimed output and lifetime ratings.

There are a lot of great, proven, reliable LED products out on the market; a quick look at a company’s showcase will give you a good sense of how long they have been out in the real world proving their products. Many are indeed ready for primetime. But be very wary when the sales rep comes calling with the latest, greatest, most amazing new LED product ever… you might get burned.

Photo Credit: Brad Koerner / Lam Partners Inc