60W equivalent LED bulb uses 9.5W and costs $13 • Hacker News Board

Re: 60W equivalent LED bulb uses 9.5W and costs $13

#11

Post by jrabone » Thu, Apr 25, 2013, 1:45 PM UTC

lucaspiller wrote: post #5

> These are white LEDs, that is, blue LEDs covered with a white-light-emitting phosphor Could someone explain that a bit more please?

There are two ways to make a white LED;

1) put red, green and blue LEDs in the same package and either bring all the connections outside for an external balancing circuit (which also lets you do multicolour effect), or balance the currents internally and just bring out two connections.

2) make a blue LED (with substantial UV output) and use a phosphor coating to re-emit "white" light. This coating appears very yellow when the LED is off, and is similar to the way a conventional fluorescent tube works.

2) is cheaper and more efficient, but only emits "white" light - the trick is getting it to not appear too blue as the phosphor doesn't absorb all the blue light.

EDIT: also, the white light from (1) is not really very white - the spectrum is hard to tailor compared to using a phosphor.

Re: 60W equivalent LED bulb uses 9.5W and costs $13

#12

Post by jessriedel » Thu, Apr 25, 2013, 1:46 PM UTC

ams6110 wrote: post #4

nakedrobot2 wrote: post #2

This is excellent. However, please do not say "this is enough for me" after you replace all your incandescent light bulbs with these. Household energy consumption is a tiny, tiny drop in the bucket compared to industrical energy consumption and shipping.

I'm not quite sure what you're saying... that the LED bulbs have a much higher energy and environmental "cost" in manufacturing, compared to a standard incandescent? That's quite likely true and has to be considered in the big picture (similar issues with electric vehicles, that their proponents like to ignore). For me the answer is simple: $13 is way too much to pay for a light bulb, I don't care how efficient it is…

> $13 is way too much to pay for a light bulb, I don't care how efficient it is.

You probably should care. It only takes 6 hours per day of usage for your 60W incandecent to suck up $13 of electricity in a year. And you'll have had to change it at least once. The LEDs will last for over a decade.

Yes, if you're only renting a house/apartment for a year then you may not recoup your costs (although it will be close). Similarly if the light is on for less than an hour per day. But if you plan on sticking around awhile it makes complete financial sense. You can literally save $200 per bulb over the lifetime of a bulb used heavily.

Also, the prices will continue to fall.

EDIT: mikeash is right that I should have mentioned the dependancy of efficiency savings on your local electricity prices. I used 10 cents per kilowatt hour, which is a bit under the national average of 12 cents (meaning I was being conservative in potential savings).

http://www.npr.org/blogs/money/2011/10/27/141766341/the-pric...

Re: 60W equivalent LED bulb uses 9.5W and costs $13

#13

Post by dragontamer » Thu, Apr 25, 2013, 1:46 PM UTC

lucaspiller wrote: post #5

> These are white LEDs, that is, blue LEDs covered with a white-light-emitting phosphor Could someone explain that a bit more please?

White light is the combination of many spectrums of light. On your monitor for example, it is red + green + blue.

LEDs however, only output one narrow spectrum. So, to solve this issue, the "white" LED is really a Blue LED + a material that converts the color blue into white.

Re: 60W equivalent LED bulb uses 9.5W and costs $13

#14

Post by whiskers » Thu, Apr 25, 2013, 1:48 PM UTC

lucaspiller wrote: post #5

> These are white LEDs, that is, blue LEDs covered with a white-light-emitting phosphor Could someone explain that a bit more please?

Based on the material used an LED produces a specific colour (wavelength). To create white light you need to emit light at all wavelengths simultaneously.

White LEDs work by emitting blue light but being coated in phosphors that emit the other colours when hit by that blue light.

Often you'll see that white LEDs appear a little "cold" in colour which is caused by the slight excess of blue light compared to the phosphor generated other wavelengths.

Re: 60W equivalent LED bulb uses 9.5W and costs $13

#15

Post by bjustin » Thu, Apr 25, 2013, 1:49 PM UTC

lucaspiller wrote: post #5

> These are white LEDs, that is, blue LEDs covered with a white-light-emitting phosphor Could someone explain that a bit more please?

LEDs emit light in a narrow frequency band, i.e. LEDs have intrinsic colors. White is not just one color, so your options to make white light from LEDs are:

1) Use multiple colors of LEDs, which will make the light source look white but objects lit by this source will have off colors.

2) Use a phosphor coating on the LEDs, where the phosphor absorbs (most of) the narrow frequency band output by the LEDs and emits the color(s) that you want.

In this case, they went with option 2 with a phosphor that absorbs blue light and emits broad spectrum white light.

Re: 60W equivalent LED bulb uses 9.5W and costs $13

#16

Post by ssmoot » Thu, Apr 25, 2013, 1:55 PM UTC

ams6110 wrote: post #4

nakedrobot2 wrote: post #2

This is excellent. However, please do not say "this is enough for me" after you replace all your incandescent light bulbs with these. Household energy consumption is a tiny, tiny drop in the bucket compared to industrical energy consumption and shipping.

I'm not quite sure what you're saying... that the LED bulbs have a much higher energy and environmental "cost" in manufacturing, compared to a standard incandescent? That's quite likely true and has to be considered in the big picture (similar issues with electric vehicles, that their proponents like to ignore). For me the answer is simple: $13 is way too much to pay for a light bulb, I don't care how efficient it is…

OTOH, my entire house is fluorescent and LED. My monthly electricity bill is $65. For a house! I never have to replace burnt out bulbs. At $13 I'd guess the LED is actually about at break-even over the life of the bulb vs incandescent unless you're buying incandescent in the big packs of 30 bulbs for $10.

The only gas in my house is my central heating, and my old water heater. I plan to replace that with point-of-use electric tankless units. No more waiting 2 minutes for hot water at the kitchen sink! With a $3,000 grid-connected solar kit I'm pretty sure I can get to near $0/month on electricity, even with the electric water heaters and the Nissan Leaf I just bought last night. ;-)

It's the future brother. Stuff lasts longer, provides a better experience and is cheaper. It's win/win/win. The environmental wins might not be all that dramatic with the impact of production factored in, but if you're in it for the long haul I figure you can still feel OK about it if you were up to replace a bulb/water-heater/car/etc anyways when you make the switch.

PS: Have you seen the price on POU tankless water heaters? Once you have the panel/breaker/wiring in place, they're dirt cheap compared to traditional water heaters.

Re: 60W equivalent LED bulb uses 9.5W and costs $13

#17

Post by Steuard » Thu, Apr 25, 2013, 1:57 PM UTC

lucaspiller wrote: post #5

> These are white LEDs, that is, blue LEDs covered with a white-light-emitting phosphor Could someone explain that a bit more please?

I'm not an expert (just a physics prof), but my understanding is that LEDs always emit one specific color (wavelength) of light rather than white light (which is a mixture of many wavelengths). So if you want to use an LED to produce white light, you set up a material that absorbs light at one wavelength and then re-emits it in a wide variety of wavelengths (that is, the phosphor).

(This is also the way that fluorescent bulbs work: the hot mercury vapor inside produces invisible ultraviolet light, but the phosphorescent coating absorbs that UV and re-emits it in a range of visible wavelengths. And it's no coincidence that they're using a blue LED with a short wavelength: in general, a phosphor can only re-emit at longer wavelengths than it absorbed. That may imply that these bulbs emit little or no violet in their "white" light, since violet has a shorter wavelength than blue.)

Re: 60W equivalent LED bulb uses 9.5W and costs $13

#18

Post by mikeash » Thu, Apr 25, 2013, 1:58 PM UTC

jessriedel wrote: post #12

ams6110 wrote: post #4

Earlier quoted context omitted.

I'm not quite sure what you're saying... that the LED bulbs have a much higher energy and environmental "cost" in manufacturing, compared to a standard incandescent? That's quite likely true and has to be considered in the big picture (similar issues with electric vehicles, that their proponents like to ignore). For me the answer is simple: $13 is way too much to pay for a light bulb, I don't care how efficient it is…

> $13 is way too much to pay for a light bulb, I don't care how efficient it is. You probably should care. It only takes 6 hours per day of usage for your 60W incandecent to suck up $13 of electricity in a year. And you'll have had to change it at least once. The LEDs will last for over a decade. Yes, if you're only renting a house/apartment for a year then you may not recoup your costs (although it will be close). S…

Make sure to state what price you're assuming for electricity when making these claims. The cost of electricity in the US can vary by a factor of 3-4 depending on where you live.

I'm sure it's worthwhile for any heavily-used light even in very cheap areas, but the specific breakeven time will vary quite a bit.

Re: 60W equivalent LED bulb uses 9.5W and costs $13

#19

Post by kyrra » Thu, Apr 25, 2013, 1:59 PM UTC

So I'm wondering how well this bulb would do in the L-Prize competition[1]. It looks like they have a number of testing requirements, but their primary goal is to have a good lumen output and lumen/watt ratio. It's run by the US Department Of Energy. Consumer Reports[2] started testing the previous winner[3] of the L-Prize competition.

[1] http://www.lightingprize.org/

[2] http://news.consumerreports.org/home/2012/08/first-look-at-t...

[3] http://www.usa.philips.com/c/energy-saving-light-bulbs/ambie...