[1]
Sorry to sound like a broken record -- see previous post from June 16th, LED T8 replacement lamps “just say no.” [2] I'll be posting the amended versions of the LED ordinance [3]later this week. A vote is expected on Wednesday, 8/18/2010.
Jim Brodrick Repeats Warnings About LED T8 Replacement Lamps [4]
July 23, 2010, by Craig DiLouie, LightNOW [1] - Guest Post by Jim Brodrick, Department of Energy
Excerpts and highlights of article:
"I was really gratified by the response to the Posting a few weeks back about DOE’s fact sheet on the performance specifications of LED T8 replacement lamps [5]. In our booth at LIGHTFAIR last month, that fact sheet went like hotcakes, because it blows the whistle on a mushrooming class of products that are not ready for prime time."
The topic is such a timely and important one that DOE has now come out with a second fact sheet that takes a deeper dive into design and application issues... Entitled LED Replacements for Four-Foot Linear Fluorescent Lamps [6], this new fact sheet not only goes into more detail about how these products don’t measure up to their fluorescent counterparts when used in 2′x4′ troffers, but also focuses on why this is the case...
That doesn’t mean LED T8 replacement lamps will never make the grade; it just means that right now they’ve got quite a ways to go – not only in terms of cost, but also in terms of light output, distribution, and lumen maintenance...when it comes to general ambient lighting for offices and other commercial spaces, LED T8s have not proven competitive with linear fluorescent lamps. This is not a vague impression “sensed” from the marketplace; it’s a DOE finding based on careful analysis and testing results from DOE’s CALiPER program [7], which has systematically benchmark-tested these products with the linear fluorescent lamps they’re designed to replace. The results of that testing have shown that LED T8s produce far less light than the fluorescents they’re intended to replace, out of proportion to the energy savings.
For example, the average initial bare-lamp light output of the LED replacement products was only about one-third of the average for the fluorescent lamps tested – with the best-performing LED T8 producing only half of the light output of a typical 4′ fluorescent. Not exactly what I’d call a stellar performance.
[8]
What’s more, because the LED products are directional, they don’t work well with the optical elements in the troffers, which are designed for omnidirectional light sources...
In terms of light color, CALiPER found that the CCT values for most of the LED linear replacement lamps were similar to the fluorescent benchmarks (3200K to 4500K), but several of the LED lamps tested had atypical chromaticities that gave the light a greenish or purplish appearance. The CRI values of the LED products ranged from 63 to 76, with most of them approximating those of lower-quality fluorescent lamps...
Add to all of this the fact that it costs a whole lot more to light a commercial office space with LED linear replacement lamps than with their fluorescent counterparts (with cost per square foot ranging from four to more than 50 times higher, and payback periods of more than 40 years in some cases), and you can see that it doesn’t make sense to use LED products for that application – at least, not yet. Solid-state lighting technology is improving all the time, but for now, when it comes to LED replacement T8s, the best policy is to “just say no.”