LEDs promises made and (sometimes) kept

by jamesbedell on January 27, 2009

in Lighting

This past Friday a fixture manufacturer came into the office to show us the latest in their LED line. I won’t name the manufacturer or the rep agency because it’s unimportant. The following is the tale of a lighting designer that wants to be green and wants to think more sustainably about his projects, and how technology still hasn’t quite caught up.  

As a primer and without giving away too much, this company specializes in making surface mounted fluorescent fixtures. They have broad national distribution and are a fairly large and well known lighting manufacturer. 
They too, however, see the future in solid-state lighting and have been working to develop their own spin on LED technology, mostly by merging the new light sources with older form factors. They also solved a problem that had been an ache of mine for quite some time, the solution moves LEDs one step closer to sustainability. It’s simple, replace-ability. 
Their answer to LED replacement was simple, turn the LED board into a “lamp” with similar form factor to a T5 fluorescent. That way if you want to change LED color, or if the fixture fails, you can replace a lamp as quickly and easily as if it were a fluorescent tube, a viable solution to one of my big LED pet-peeves and that wasn’t the only intelligent move the company made. They also decided to bring their driver technology in house, by creating a consistent driver they plan to keep in production for at least five years. The reasoning behind this is also sound. The relationship of a driver to an LED isn’t all that different than that of a ballast to a fluorescent lamp. Different drivers produce different brightness and color temperature results in a given LED. So it makes sense from the manufacturer’s point of view to keep the drivers consistent so as the LED chips inevitably change and improve there is a least one strong constant for comparison. It also means as a specifier I have a simple way of comparing LED performance from year to year. 
So then what’s the problem? Solid power-train, better form factors, the lumens per watt numbers were in the strike zone, so what could I have to complain about? Well at the moment of truth (i.e. when the fixture turns on) it all went downhill. 
The linear LED was supposed to achieve “consistent lamp to lamp color” by mixing the slight variations of warm white with the fixture a few inches away from the surface it was meant to light, the further the light from the surface the better the color. Or so they said, until….
Six lamps were on the board and as expected they each presented a 150 degree kelvin variation (or so) except for the middle LED which looks about 500 degree variation, you could have pulled the fixture 20 feet from the wall and seen the deep warm spot. His presentation falling apart, the rep felt the need to explain, but he didn’t need to. I’ve seen this before from fixture manufacturers at the mercy of their LED counterparts-great engineering, efficiency and in many cases even cost per unit. Then we see it on and the optics are just not acceptable. 
So while we all want to get more efficient and LEDs get better and better every 6 months,  until color consistency and bin matching are addressed lighting specifiers are going to be reluctant to get them on jobs. I urge the LED makers out there, get color right first, then keep pushing those lumens, maybe then we’ll be able to spec you more often.

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