Over the last couple of years there has been a very rapid development of LEDs. Some problems still remain, others have been mitigated in innovative ways. Summary from some of the latest studies, reviews and consumer tests (links below):
1. Prices have gone down, from shockingly overpriced to reasonably affordable (≈ 4-40€) (1, 2, 3).
2. Brightness. More higher lumen models (600-800 lm have been introduced, and even a few 1100+ lm), but most LEDs are still low-lumen (≈ 400 lm) – which make the least economic and environmental sense to replace and make dimmable.
3. Efficacy (lumen/watt) has improved (≈ 80 to 96 lm/w). (My comment: But as always, only if not including poor power factor and heat replacement effect in colder regions.) Both watts and efficacy were found to be overstated in many of the lamps tested, sometimes understated. Usually just by a few per cent, but some lamps gave up to 39% less light than claimed on the box (1, 2, 3).
4. Colour rendering index has technically improved (CRI over 80 for most LEDs, a few even over 90). This, however, does not mean that the spectral power distribution is as even or full-spectrum as incandescent and sunlight, only that it has been tweaked to reproduce the required 8 colour samples more accurately when testing.
5. Light colour has improved for many warm-white LEDs. Only a few years ago most LEDs were a ghastly cool-white and the few marketed as “warm-white” could be anything from yellow, orange, greenish, blueish, or pinkish to a dull grey-white. Now, many LEDs have reached a similar decently warm-white emulation as CFLs finally did after 20 years, but the light colour may still vary between models and correlated colour temperature is often somewhat colder than the stated 2700K, according to the latest Swedish consumer tests (2, 3).
6. Colour consistency over time seems to have improved. A multilateral (pro-LED) European study found that only a few lamps exceeded the 6 MacAdam step tolerance limits after 100 and 1 000 h testing (1).
7. Power Factor can still be a problem and may vary greatly between different brands and models – without obvious connection to price. In the last U.S. DoE tests 2011 PF varied from 0.58-0.98 (6). The 2015 European study found all tested samples “to comply with EU requirements” (1). (But the EU requirements for home LED lamps under 25 W is only 0.5 – which means that those with poor PF may still use up to twice their rated energy!)
8. Dimmability. More LEDs are dimmable – but many are still not compatible with all dimmers, so read the specifications carefully. Some of the dimmable samples tested by Testfakta started humming, flickering or shut off completely when dimmed (2). The European study found similar problems (1).
“Five of the LED lamps purchased for this study were marketed as ‘dimmable’. Of these, two of those lamps were able to be dimmed on both types of dimmers (#6 IKEA, #13 Star Trading). The other three lamps had issues with one of the dimmers. Lamp #5 from LED Connection was not compatible with the leading edge dimmer and Lamps #14 from OSRAM and #15 from Philips were not compatible with the trailing edge dimmer.”
9. Warm-dim LEDs. A new generation of LEDs which turn warmer when dimmed have been introduced, thereby better mimicking natural filament lamps – one of the complaints of earlier LEDs and CFLs. These are more expensive, of course (≈ 15-20 €.) (Will test and post review later.) From the Osram press-release:
“In the evenings, and especially when evenings become longer, many people love the snug, warm glow of a burning candle or open fire. Incandescent and halogen lamps create similarly cozy light by simple dimming, but with modern LED lamps this is technically not quite as simple. To create the popular light effect with 2,000 Kelvin here as well, Osram has integrated state-of-the-art LED technology into its new Glow-Dim models.”
(My comment: Funny that that warm romantic glow, priced by so many, was completely ignored by the lighting industry and legislators both, when it was produced by incandescent lamps. But now that there is a synthetic, heavily overpriced, replacement this quality is used to sell a fake copy of the real thing which we all used to love.)
10. Flicker can still be a problem in some lamps. Last summer Hillevi Hemphälä at the Lund Technical Institute started testing LEDs for flicker. She says it’s hard to for the consumer to know which lamps are good or not, as this is not always reflected in the price. There are LEDs powered by a pulsed current, which is a cheaper construction and facilitates dimming, but it can also increase subliminal flicker. “Problem med flimmer från LED-lampor” Final test results are yet to be published. Testfakta found the flicker index to vary between 0.01 (virtually no flicker) to 0.11 – but no correlation with the price (2). The multilateral European study said, “The flicker index and percent flicker of the lamps were measured and many lamps had no flicker” (1) – which is a roundabout way of saying that the rest of the lamps did have flicker.
11. Life span appears more reliable than for CFLs. LEDs don’t seem to be sensitive to rapid switching on/off, only to overheating which may make some LEDs expire prematurely.
2014, customers were not so impressed (4):
“We lit up your frustrations when we last spoke about LED light bulbs. More than 300 comments were made, most of them about their poor performance and your dissatisfaction with them not living up to their lifespan claims.”
“We’ve tested 410 LED light bulb samples for 10,000 hours or more, and 75 of those (18%) failed within 10,000 hours, even though they all claim to last much longer. And 69 out of the 185 bulbs (37%) we examined at the 15,000 hour mark had failed by that point. Again, almost all of them claim to last longer than this. So, although there are advances, there’s still room for improvement.”
Swedish consumer test magazine Råd&Rön says all their earlier tested LEDs have lasted longer than 5 000 hours so they discontinued durability tests for LEDs, as the models involved would be replaced in the market by the time the long-term test was done (3).
Philips famous L-prize LED has now passed 40 000 hours with no failures and 93.7- 97.5% lumen maintenance, which is very good compared with CFLs (5). (Its 70€ European cousin is still burning nicely in my outdoor luminaire after 3.5 years.)
In the European study, a few LEDs were non-functional right out of the box ().
“Three of the 170 LED lamps tested were defective and did not operate out of the box (and thus could have been returned for a refund / replacement) – thus these lamps were not used in our testing and those models simply had smaller test samples studied. Two individual LED lamps sold by ccLED (both sample #11) failed during the burn-in. Lamp #12 had one unit fail during measurements, but all the other LED lamps so far have not have problems after 1000 hours of testing.”
12. Light distribution has improved. Spreading the light equally in all directions has been a challenge as diodes are naturally directional with quite a narrow beam angle. To get around that problem, diodes were first just placed around a central stick – with mediocre results. Some brands have now solved this by adding a diffusing lens over a single power-LED die – which also markedly increases the price but gives a light distribution more like that of a traditional bulb (though never with the same sparkling clarity, sunny feeling, or beautiful glow, of course).
13. Filament LEDs. A new type of filament LED has also been introduced, both to give a better 360° light, and to replace the old Edison-type decorative carbon filament bulbs (which is probably why the EU commission is now removing the exception for those in the latest Directive amendment). It consists of tiny diodes packed closely together on 2 to 8 filaments inside the bulb. This also reduces internal heat and the need for a heavy and cumbersome heat sink, so this type of lamp can be made neater, more light-weight and closer to the original incandescent bulb. (Again, interesting how so much effort is put into trying to emulate all the quality and design advantages of the banned bulb if it was so bad.)
I tested a filament LED with CRI 90 (= improved colour rendition) from Star Trading. For me it was still not close enough to want to replace a real incandescent bulb in my living room, but OK for outdoors. Others might find it acceptable.
14. Temperature-tolerance. LED lamps are ideal for outdoors, even in the winter, as they are not sensitive to cold like CFLs (which can take forever to light up in cold temperatures). Outdoor lamps are also the most worthwhile replacing if left on for many hours per day, or night. However, LEDs are still sensitive to heat and cannot be used for example in a sauna. Only incandescent/halogen lamps tolerate heat well.
15. Health risks risks may still be an issue. This LEDs Magazine summary is from 2010 but LED light has not changed substantially, other than glare often being less of an issue than with early lamps. But they still contain more blue light which can irritate the eye, disrupt circadian rhythm and be harmful to people with blue-light sensitive eye conditions. Flicker can also be disrupting (and for epileptics even dangerous). Others experience a various symptoms, e.g. migraines, vertigo, nausea, inexplicable visual distortions that make it impossible to see in LED lighting and much more. An anecdotal example sent to Incandescent Anna:
“I am extremely sensitive to LED lighting both indoor and outdoor. They have been erected outside my home and now I can’t even step in to my own front garden without symptoms of severe eye pain, migraine, nausea, vomiting, aura, vertigo, increased heart rate and ringing in my ears. It hits me immediately and the severity and length of symptoms depend on the length of time I’m exposed. I have known for 7 or 8 years of this extreme intolerance to LED when I first got a DS Lite, back-lit with LED and I couldn’t bare to look at it. I can’t use any LED backlit phones or monitors. I don’t think that my symptoms are getting worse but my recovery period is now non existent because LED is everywhere. If I am round CFL for a prolonged period I develop headache and agitation but nothing like the symptoms I have around LED.”
16. LED li-fi. LED lamps can now be used for delivering ultra fast wi-fi. Considering how many have experienced severe symptoms from smart meters, does this sound like a good idea?
Tests & Reviews
1. Test Report – Clear, Non-Directional LED Lamps (Swedish Energy Agency, Belgian government, CLASP’s European Programme, eceee, 2014-2015)
eceee – summary of above test
2.Testfakta – test table (Sweden 2015, partly in English)
“LED närmar sig glödlampans ljuskvalitet” (test article in Swedish)
3. Råd & Rön – LED test (Sweden, 2015-2016, 25 SEK to read)
4.“A Nobel Prize for LED bulbs but do they get your vote?” (UK, Oct 2014)
5. “DOE Testing of L Prize LED lamp passes 40 000 hours” (USA, Aug 2015)
6. U.S. DoE – CALiPER SSL tests (USA, 2007-2016, detailed but not very updated)
Stiftung Warentest – Lampen im Test Das beste Licht für Sie (Germany, 2015, 3€)
Consumentengids – Test Ledlampen.pdf (Netherlands, 2015)
CNet – Best LED Light Bulbs (2016)
Best LED Light Bulb Reviews and Comparisons (2016)