Philips has announced that its 22-watt LED lightbulb is the first 100-watt tungsten equivalent bulb to have been awarded Energy Star certification. Often referred to as the A21, which is actually just one of several standard forms for light bulbs that this bulb happens to conform to, Philips' 22-W bulb puts out "nearly" 1,800 lumens for an efficacy of about 82 lumens/watt (lm/W). It's a fine spec, but not too dissimilar to the competition, which raises the question of why Philips' product has been singled out.

The bulb's efficiency is right up there with other 100-W equivalent LED light bulbs we've looked at from Osram Sylvania, GE and Switch. There was some confusion as to the exact efficacy of Osram Sylvania's offering at the time of its announcement, but its Amazon listing now quotes an output of 1,675 lumens giving it a superior efficacy of 84 lm/W, though other sources put the efficacy at 80 lm/W (a note on efficacy and efficiency: technically there's a distinction.) The current specs listed at Switch Lighting's website means its efficacy has to be reined in from the figures we were quoted at the time of our reporting.

The 1,600 lumen output of Osram Sylvania's, GE's and Switch's bulbs is actually worse than that of a 100 W tungsten bulb (about 1,750 lumens). Philips' bulb, on the other hand, exceeds this output. However, the 1,600 lumen output is still sufficient to achieve Energy Star rating, so why is Philips' bulb the only one to have been certified?

The Philips press release gives some insight into the requirements of the certification process for such a product. In addition to the 1,600-lumen minimum output, lamps must achieve a color rendering index of 80 (good, but not great) and a rated life of 25,000 hours (which is the time it takes for the light output of the LEDs to drop to 70 percent of their initial output).

However, though definitive spec sheets of these lightbulbs are hard to pin down, a color rendering index of 80 is not particularly onerous, and, given that LED lifespans are frequently quoted at 50,000 or even 100,000 hours, neither is a 25,000-hour rated life. Indeed, a glance at the Switch spec confirms that the bulb meets the Energy Star requirements. It seems very possible, if not downright likely, that Osram Sylvania's and GE's 100-W-equivalent LED bulbs do the same (this report in LEDs Magazine suggests that Osram Sylvania's bulb is indeed up to snuff.)

So, as fine as it is, precisely why Philips' bulb has been certified over Osram Sylvania's, Switch's, and potentially GE's is something of a mystery. If there's a reason similar products have not been certified, this would be useful to know. If there's not, the apparent singling-out of Philips would seem to be a little unfair. We've asked the manufacturers and Energy Star for insights. We'll let you know if we have any more to add.

Update 04.04.2013: Thanks to reader Daniel Henderson who pointed out that LED life span is defined as a percentage light drop, not a failure rate. The article has been amended to rectify this.

Update 04.05.2013: A Philips spokesperson has been in touch by email, and has shed some light on the Energy Star certification process. Interestingly, the results of the test put the bulb's performance as superior to the rated figures. Rather than rehash the email, here's what we received:

Anyone can submit their product for Energy Star testing, which includes 3,000 hours in lab testing, as well as other types of testing that confirm that the product lives up to its claims, including checking the beam angles, how well it performs, light quality, etc. Our bulbs are developed with Energy Star standards in mind because we want to ensure that they qualify for utility rebates that will help lower their cost for consumer, as well as giving them the assurance that they are getting a quality product. Some of stats from the testing:

  • The min lumens for ES qualified 100W incandescent equiv is 1600 [lumens], our lamp tested 1780 [lumens] – exceeded by 10.6 percent

  • Our rated wattage is 22 W, but the LM79 data showed 20.8 W
  • Based on those measurements our efficacy is 85.8 lm/W, one best in the industry for a bulb of this type
  • Though this bulb may be best in class (its 2,700 K warm appearance does no harm in this regard), it's still not precisely clear why no other products have been certified. Philips has kindly offered to answer further questions – an offer we'll certainly take them up on. Our conversations with the other players are ongoing, so stay tuned for a follow-up article in the coming days that will hopefully shed more light (if you'll pardon the phrase) on Energy Star and LED light bulbs.

    Philips also sent through an image of this 100-W incandescent equivalent LED bulb. The image we originally ran was of the similar-looking 60-W equivalent. Apologies for any confusion caused.

    Update 04.13.2013: For the resolution of some of these questions, see Gizmag's feature, A tale of two tests: why Energy Star LED light bulbs are a rare breed.

    Source: Philips