Energy Star Wars - 120Hz vs. 150Hz for Integrated LED Lamps
Talk Back
There is a real dust-up occurring over the Dec 18 2009 publication of Energy Star criteria for Integral LED Lamps (retrofit lamps.) All of the action surround a change in LED operating frequency from the draft 120Hz to 150Hz in the final revision. No explanation was provided.
A review of the comments provided during the three draft phases reveals only one organization commenting on this topic at all - NEMA/NGLIA. In this, the comments offered in draft two and draft three conflict with one another. In draft two, NEMA suggested DOE drop the frequency to 100Hz or 110Hz to accommodate possible fluctuations in actual power line frequency, In draft three, the same organization commented that the frequency of 120Hz may present apparent flicker to "some" people, and that a human factors expert should be consulted. As a footnote to this comment, the book "Human Factors in Lighting" was cited as recommending 150Hz (assumed to be the source of the change to 150Hz in the criteria). Digging into this, in review of the book, no such recommendation can be found.
For reference, the SSL Luminaires standards for Energy Star all include a >/= 120Hz requirement. There were no comments from NEMA during the reviews of those standards on the topic.
There are several manufacturers expressing their feeling of unfair treatment on this topic. Some have gone as far as demanded a freedom of information disclosure of where the change to 150Hz originated, feeling that the DOE failed to follow proper procedure for making such a change without comment. Others have accused the DOE of responding a certain strong arming manufacturers, who want the market to themselves.
At best NEMA comments on this topic should be set aside as inconsistent. Reading the comments in detail makes one wonder whether the comments are qualified or just conjecture. The inaccurate reference to the book is also troubling, as this raises the issue of credibility on the topic as well as intent.
The entire issue of flicker in LED standards across all segments should be addressed realistically. There is no way to attain a 150Hz operating frequency without introducing driver electronics that he AC LED providers eliminate in the interest of simplicity and cost reduction, so that should be taken off the table. There are other ways to reduce flicker from AC operation of LEDs, such as inclusion of rectification circuitry to create an underlying DC component that significantly reduces the contrast of on-off cycling that aggravates appearance of flicker.
Not every product will qualify for Energy Star, as it should be. However, blocking an entire class of technology based on anecdotal commentary not backed by scientific study or accurate reference is in error in procedure and unfair to those effected. Since there are no studies indicating that a change from 120Hz to 150Hz will improve the likelihood of some individuals to perceive flicker - the change itself should probably be reconsidered. Until such time as there is objective research that can be used to establish an improved standard, the criteria should remain consistent with the luminaire criteria at the very least.
If the issue of flicker proves to be problematic, or is investigated fully, with new recommendations applied that can be proved to produce a significant gain, while providing opportunities for multiple approaches to compliance, an update to this criteria can be made at that time.
Kevin Willmorth
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