Time to write a little summary about solid state lighting a.k.a. LED and what has transpired over the last couple of years.
I have yet to see a warm-white LED that looks like a decent incandescent replacement. I went to the Nordic Light Fair again last year too but the warm-white LED lamps had not much improved. (I’ll keep checking.)
Update Aug 2012: This summer I’ve seen some good-looking warm-white LEDs, first at the Arlanda Airport and as streetlights in a Stockholm suburb, and then yesterday I got a look at Philips MyAmbiance LED bulb in a Swedish hardware store. So, it seems it can be done. However, these examples are from the very top end of the market – at the beginning of their life. The majority of LED bulbs for the consumer market still look absolutely horrid.
The glaring cool-white LEDs I find hard on the eyes and not at all suitable for Scandinavia, where we are used to the warm glow of incandescent light in the winter time. Two years ago they tried replacing the lamps by the creak in one of Sweden’s most picturesque little towns to cool-white LED, but had to remove them quickly as the result was ghastly and people complained. Now that town is lit by incandescent-looking ceramic metal halide and warm-white good quality CFLs, which is ok even though quite not as pretty and romantic as when it had real incandescent lamps along the waterside.
I also recently checked out an LED-lit tunnel in Stockholm and found the bright cool-white light dangerously glaring. Much more so than the standard linear fluorescent or sodium HID lamps usually used in tunnels (and I’m not crazy about those either). Shops lit with LEDs tend to look cold and sterile, rather than warm and inviting. Could be that I’m female, many men seem to love the cold harsh light. Here is a similar opinion from another woman (emphasis added):
Whenever I try to study in Meriam Library I feel like I’m on an examination table in a surgery room. Either that or in a jail cell or a mental institution. The lights are overly bright and they make a buzzing noise that interferes with my ability to concentrate. I’ve stopped going. /…/
Now, whenever I walk up the Esplanade to get home at night, I notice that the LED bulbs cast a sharp bluish-white light that brightens the whole street. I understand that peripheral visibility will greatly increase for drivers, but they are just too bright.
They remind me of Meriam Library but on greater scale.
If these energy-efficient bulbs take over streets and even in-house lighting, you have to ask yourself – do I want everything around me to feel like a night game of football or baseball?
What’s worse is that these lights will affect space observatories in cities across America, causing an effect that doesn’t seem be taken as serious as when smog from cars damages air quality. That effect is called light pollution.
LEDs are actually more dangerous than the old incandescent bulbs because they cause a glare for drivers and create more shadows, said Kris Koenig, director of the Kiwanis Chico Community Observatory.
“Cities are going to want to open light again where they’ve been restricting light for decades,” Koenig said, in a phone interview. “There are even studies that show that light at night causes sleep problems for humans and animals.”
And last year scientists found that LEDs – like most electronic products, surprise surprise – contain some toxins too (my emphasis).
“LEDs are touted as the next generation of lighting. But as we try to find better products that do not deplete energy resources or contribute to global warming, we have to be vigilant about the toxicity hazards of those marketed as replacements,” said Oladele Ogunseitan, chair of UC Irvine’s Department of Population Health & Disease Prevention.
He and fellow scientists at UCI and UC Davis crunched, leached and measured the tiny, multicolored lightbulbs sold in Christmas strands; red, yellow and green traffic lights; and automobile headlights and brake lights. Their findings? Low-intensity red lights contained up to eight times the amount of lead allowed under California law, but in general, high-intensity, brighter bulbs had more contaminants than lower ones. White bulbs contained the least lead, but had high levels of nickel.
“We find the low-intensity red LEDs exhibit significant cancer and noncancer potentials due to the high content of arsenic and lead,” the team wrote in the January 2011 issue of Environmental Science & Technology, referring to the holiday lights. Results from the larger lighting products will be published later, but according to Ogunseitan, “it’s more of the same.”
Lead, arsenic and many additional metals discovered in the bulbs or their related parts have been linked in hundreds of studies to different cancers, neurological damage, kidney disease, hypertension, skin rashes and other illnesses. The copper used in some LEDs also poses an ecological threat to fish, rivers and lakes.
Ogunseitan said that breaking a single light and breathing fumes would not automatically cause cancer, but could be a tipping point on top of chronic exposure to another carcinogen. And – noting that lead tastes sweet – he warned that small children could be harmed if they mistake the bright lights for candy.
I must say that I find that risk a lot smaller than accidentally breaking a CFL at home and breathing the mercury vapour. Breaking an LED is not so easy (although I managed to drop one and broke the outer bulb) and you normally don’t pulverise them (“don’t try this at home!”). But they should absolutely be recycled as electronic waste and not thrown in out with household garbage.
(As an aside: In connection with this article being quoted around the web I’ve also seen some erroneous claims that incandescent lamps contain mercury – which is not true at all – and lead, which used to be true but not after 2006.)
Promised longevity may also not be what one expected:
When it’s said that a standard light bulb will last 1,000 hours, that is the mean time to failure: half the bulbs will fail by that point. And because lamp manufacturing has become so routine, most of the rest will fail within 100 hours or so of that point.
But LED lamps don’t “burn out.” Rather, like old generals, they just fade away.
When a manufacturer says that an LED lamp will last 25,000 or 50,000 hours, what the company actually means is that at that point, the light emanating from that product will be at 70 percent the level it was when new.
Why 70 percent? Turns out, it’s fairly arbitrary. Lighting industry engineers believe that at that point, most people can sense that the brightness isn’t what it was when the product was new. So they decided to make that the standard.
Of course, brightness is subject to the old frog in the boiling water syndrome. I’m sure that most people won’t even notice the lower level then, if they’ve lived with the same bulb for its entire life.
Philips & Color Kinetics explains it more in detail:
This 70% of the level of original output is called L70 by the lighting industry. ASSIST recommends defining useful life as the length of time it takes an LED light source to reach 70% of its initial light output (L70). For decorative and accent applications, ASSIST recommends defining useful life as the length of time it takes an LED light source to reach 50% of its initial output (L50).
So up to 30-50% is seen by the lighting industry as a perfectly acceptable level of light loss just because we get used to it over time??
Testing also seems difficult, making one wonder how the life span numbers given for LEDs are arrived at (emphasis added):
LM-80 requires testing of LED light sources for 6,000 hours, and recommends testing for 10,000 hours. It calls for testing LED sources at three junction temperatures — 55° C, 85° C, and a third temperature to be determined by the manufacturer — so that users can see the effects of temperature on light output, and it specifies additional test conditions to ensure consistent and comparable results.
Unfortunately, LM-80 provides no recommendations on how to extrapolate measured data to L70 or L50. Such a methodology, IES Technical Memorandum TM-21 is currently under development. Until TM-21 is published, the only way an LED source manufacturer can claim that their L70 and L50 figures conform to LM-80 is to measure their LED sources until they reach those thresholds. Since a typical L70 number is 50,000 hours, such a test would last longer than five years! Not only would this test be impractical, but LED technology evolves so quickly that a given product would be obsolete by the time the test was completed.