It was in Hong Kong at the 2016 International Lighting Fair where I saw my first LED filament lamp. Up to that point, the retro-fit LEDs available just weren’t (and still aren’t) hitting the visual and performance sweetspot. They were (are) less than attractive to look at and the use of the opal envelope seriously compromised lamp efficacy. At a time when decorative lighting was finally making inroads into the design landscape, it was vital that we found something that mimicked the old GLS filament lamp . . . and here it was!
Since then, we’ve seen improvements in the light delivery of these LED filament lamps (and I’m glad to see that the fashion for hipster Edison envelopes is quietening); we can now enjoy dimmability, dim-to-warm technology and the conventional like. But we still don’t have a real across-the-board standard on the way that these lamps work, so whenever a new exciting development comes along, we need to dig deep to make sure that all of our desired design criteria are met.
Which brings me to the headlines being generated by the latest EU-A rated LED filament lamp from Philips /Signify. And those headlines are very impressive: after all, at 210lm/W, the 60W-equivalent lamp is rated at only 4W and promises a 50,000-hour life.
But its so important that we dig down into the specification, because – as we all know – the devil is in the detail, and there are a few things here that should provide cause for concern for any specifier.
I fear that the development guys have fallen foul of some of the inevitable LED technical limitations and have chosen to concentrate on the energy rating at the expense of how the lamp works in use. This is a ‘consumer’ product, so we need to think about it in the residential context. Certainly, the supply route, via Amazon, Argos and John Lewis reinforces that perception.
Here’s what concerns me:
Colour temperature: only 3000K and 4000K unfortunately and, with the best will I the world, I can’t agree with the Philips marketing blurb that claims a ‘beautiful, warm white light’ for the 3000K version. One of my regular conversations with clients is to assure them that LED lighting can provide beautiful warm light because the LED filament lamp typically sets out its stall at 2700K.
Colour consistency: while I don’t think its quite as serious issue as in other sectors, I’m not too happy to see a 6SDCM rating for the consistency of these lamps, and that’s only offering CRI80, which just feels shabby in the likely use-circumstances.
Technical performance: the stand-out issue here is the Power Factor, coming in at a lowly 0.4. I know that there has been debate about the relevance of PF in the residential sector, but I would make the point that, with off-grid power generation becoming more relevant in an energy-vulnerable world, the ‘silent killer’ that is poor Power Factor can wreck all the design calculations needed to determine the power capacity required for any project. If a 4W lamp is actually ‘consuming’ more than 8W, that’s a concern.
Oh yes . . . and its not dimmable. ‘Nuff said on that one.
At least, all of the information I mention above is in the technical specification for this lamp, so a nod of respect to the manufacturer for not hiding it’s intrinsic limitations. It will be the case that what the light looks like on a daily basis will ultimately trump the exceptionally lower energy rating of which the manufacturer is so proud. My fear is that potential users will ultimately be disappointed because their presumptions have not been met. Yes, of course they should have checked (caveat emptor!), but that does assume a level of technical knowledge on the part of those doing the checking.
I don’t know the price of the lamp yet, but let’s remember that it’ll be a financial commitment that’s likely to last for the user for many years into the illuminated future. It really needs to deliver on more of its performance criteria.