[mrobert]

I use economic lights.
A bulb uses 22Watts, and the light is equivalent to that of a 110 Watts bulb.

What I really like, is that they are not blinding me.

ANd my bill went down like crazy

[WisJim]

There have been studies done about "security lights" at homes, farms, and businesses, and they have found that they are only beneficial if they maintain illumination in an area that is already well-lit with other lights, such as street lights. In other words, security lights or yard lights aren't a good idea in rural areas as they seem to make it easier for burglars, etc., to find their way around. On the other hand, I have noticed that the goal in my city seems to be to maintain a lighting level adequate to read a newspaper anywhere in town at any time of day or night. The level of street lighting is getting overwhelming. I agree with the poster that mentioned eyes not adjusting to the dark as being a problem.

Most people should just stay in at night. They don't want to deal with the outdoors anyway, it is always too hot, too cold, too something for what seems to be the majority of folks that are getting better adapted to sitting on their butts and wathcing TV than they are in dealing with the physical world outside of their doors.

[Narz]

I really like LED light.

I first started noticing the difference in light as a lad of 13 at a all boys boarding school in cold ass New Hampshire. As you can imagine I was pretty depressed but getting a halogen lamp in my room suprisely brightened my mood considerable despite the circumstances (more consistantly so than the slew of psych drugs my parents tried on me over the years).

Of course halogen is quite expensive, even compared to conventional bulbs. Fluorescents are cheap but they aren't plesant. LED lights make me happy. They are so damn expensive though.

Anyhow, what LED lightbulb (for a regular sized socket) should I buy. Ideally about as powerful as an 100 watt "regular" bulb.

Thanks,
Narz

[FoxV]

wow, 100Watts equivalent is a really tall order (1000lumens).

Here's the site I get my LEDs from
Superbrightleds.com
They have a good selection of bulbs as well, but nothing that comes any where close to a 100W incandescent.

If you want that kind of light output you'll have to make the "bulb" yourself. Superbirghts have a very nice 9000mcd 360degree LED that can be driven up to 20,000mcd (although, I'm not sure how long they'll last with prolonged use at that output).

The LEDs are expensive (and double the hieght and width of a regular LED) but I would say its your only chance at reaching the brightness you want. You'll probably need about 40 of them (about $70 worth).
RL8-W110-360

This is actually a considerable advancement, I tried to make a "bulb" a few years ago. With over $100 worth of LEDs, I managed to get what I thought was about equal to a 40 - 60 watt bulb (with todays prices, it would only be about $40, so we are getting there)

[Narz]

Thanks for the site.

How come LED's are still so pricy?

[FoxV]

My guess is that there's just not enough mass market for the High brightness LEDs. They are really taking over flashlights and tail lights, but outside of that they're still a niche item (used in day Facade video screens, difficult to repair lighting applications, and Traffic lights).

But as the price comes down, they'll eventually get put into a wider range of applications (Audi just came out with an LED headlight).

I also saw that Wal-mart has an LED bulb now as well. Its a multicolor one that flashes 5 different colors, and has the brightness of a small night lite for $15. Nothing to get excited over, but a product showing up in Wal-mart usually marks a turning point

btw, even though I'm a big fan of high brighness LEDs, I don't think they'll do squat in grand PO scheme of things, but they could at least make the new dark age a little bit brighter

edit---
oh ya, and incandescent christmas lights are now becoming a thing of the past. And about freak'n time too

[FoxV]

As you can imagine I was pretty depressed but getting a halogen lamp in my room suprisely brightened my mood considerable despite the circumstances

btw, this just reminded me of when I was in University, in a beige 7'X9' cinderblock cell of a room.

The lighting was horrible, made worse by the drab paint, and a drab atmosphere. My solution was to wire up a full size flourescent ballast (double 48" tube type).

My room on the upper floors of residence could be see from all over the campus. I became the "lighthouse of Res"

did wonders for my mood as well

[SolarDave]

I like these for directional light:

PAR20 LED Lights

I bought 20. I replaced 16 50 Watt Halogens and gave the rest away as christmas presents.

NO, they are not as bright as the halogens.

YES, they are bright enough.

[snax]

btw, even though I'm a big fan of high brighness LEDs, I don't think they'll do squat in grand PO scheme of things, but they could at least make the new dark age a little bit brighter

Well yes and no.

I think that the option makes the idea of converting to a PV array more feasible. Every improvement in efficiency reduces the required size and cost of the array.

Are most people going to cenvert to PV because they can now buy LEDs? Er . . probably not.

[Bas]

I LED's they, are really cheap to make (apart from development costs which are still very high per unit right now) And considering they only use about a quarter of the power traditional bulbs use to produce the same amount of light + the fact that lighting takes up a big portion of our total electricity bill makes me think this is the most promising technology when it comes to reducing our energy needs..

Also because they practically last forever they are really not that expensive. And I'm glad to hear the "warmth" of the light they produce is satisfactory as well

[Narz]

I just got ordered one of the crank flashlights (the Freeplay Jonta one, seemed like the best). I'll let y'all know how it is. Good for emergencies, hopefully will last long time and good for reading in bed while 'the wife' is asleep.

[gg3]

Freeplay is the gold standard for crank-powered devices. Most of them now come with a small PV cell and batteries, so you can charge them up by day and have light at night.

Freeplay also makes an LED lantern for about $40 with a crank, battery, and wall-wart transformer. Fully charged it's good for @ 2 hours at max brightness, or up to 70 hours at night-light levels. This is on my list of things to get when I have time.

LEDs are typically rated for 100,000 hours (when not being overdriven), which translates to 12 hours a day for @ 22 years, or about 34 years at 8 hours per day. The thing to do is to stockpile a few LED bulbs now and get more as price comes down.

---

The entire concept of room lighting has to be re-thought. The idea of having full daylight at night has to go. Instead, think of task lighting: a lamp over the reading table or desk or kitchen counter. The only place in the house that really needs general area lighting is the bathroom, because the obvious three "task areas" (toilet, sink, tub/shower) are so close to each other that task lighting them would end up lighting the room altogether.

Task lighting generally produces enough spill-over light as to illuminate a room sufficiently to enable walking around etc. without bumping into things. That will suffice in most cases, and a low-level general room light can make up the difference. Thus we might see odd combinations such as a single candle or oil lamp to light a room, and an LED bulb lighting a desk in a corner of the room.

[smallpoxgirl]

Not trying to derail this thread, but LED's are actually not a very energy efficient light source. The average white LED produces about the same number of Lumens of light from a watt of electricity as an incandescent bulb does. They are much less efficient than fluorescents. That doesn't mean they are bad. There are special properties of LEDs that can be useful in some applications. They are very good at producing highly directional light such as a flash light. They are also a very efficient way of producing colored light such as a tail light or a traffic signal.

This site: link gives the break down of the luminous efficiency of various light sources.

A lot of the claims of increased efficiency of LED's are based on comparing candella per watt instead of comparing lumens per watt. Candella is a directional measurement: How much light the source makes in a given direction. LED's are good at making directional light. Lumens is the total light output in all directions. LED's are not very efficient in Lumens per watt.

This site lists a number of 120v LED bulbs. link The most efficient is 56 lumens per watt, but most are in the 20-30 lumen per watt range. For comparison, Incandescents are generally in the 17-20 range, regular fluorescents run from 60 to 100 lumens per watt, and compact fluorscents are generally in the 45-60 lumen per watt range.

Notably, most of the listed LED bulbs also produce quite cold light. The warmth of artificial light is expressed in K (i.e. kelvins). A "colder" light correlates with higher K and a "warmer" light correlates with lower K (It's somewhat counterintuitive as it's the opposite of the way the temperatures go.) An incandescent generally is in the range of 2700-3000K. Typical cool white flourescents are in the range of 4000K. Warm white flourescents are in the range of 3000K. "Day Light" flourescents have the coldest light of all at about 5000K. Most of those LED bulbs, you'll note, produce very cold light...in the range of 5000K to 7000K.

[tsakach]

Not trying to derail this thread, but LED's are actually not a very energy efficient light source.

Um, led lights are actually very efficient now due to dramatic improvements that have occured within the last year.

The latest led devices available for purchase are rated at 70 lumens per watt. As a reference, conventional incandescent light bulbs are typically in the 10 to 20 lumens per watt range, while compact fluorescent lamps range from 50 to 60 lumens per watt. The latest prototype leds have been verified by NIST as having efficiencies up to 131 lumens per watt.

In answer to your question as to the best Led bulb, the Cree XLamp is a good candidate. White light Cree leds at 70 lumens per watt are available for purchase now:
Cree® XLamp 7090-XR SMD LED

Articles on the newest prototype leds at 131 lumens per watt:
White LED raises efficacy benchmark
Cree Demonstrates 131 Lumens per Watt White LED

Here is a wikipedia article with a table comparing lumens per watt for various light sources:
Wikipedia: Luminous efficacy

[smallpoxgirl]

In answer to your question as to the best Led bulb, the Cree XLamp is a good candidate. White light Cree leds at 70 lumens per watt are available for purchase now:
Cree® XLamp 7090-XR SMD LED

By comparison this bulb: link Has the same luminous efficiency, produces light with similar warmth, costs about 100 times less per lumen, and screws into a normal lamp.

Maybe when the prototype type stuff comes to market there would be some reason to convert to LED lighting. For now it only makes sense in flashlights and colored lighting. Anywhere else, it's an expensive gimick.

[tsakach]

Since I am off grid, I switched to led lighting over two years ago to minimize energy consumed by lighting. What I learned from using led lights is that you don't need to have everything brightly illuminated. You can get by on much less energy through a combination of small spotlights and low level blanket coverage of large areas. In my case, I use less than 10 watts for everything.

Energy used by led lighting can be stretched further with techniques such as dimming the light slightly with pulse width modulation. Pulse width modulation has the advantage of not requiring a resistor in series with the led to limit current, and does not cause the led to heat up, extending the life of the led substantially.

Combining white light leds with efficient pwm drivers is an unbeatable combination for reducing energy consumed for area lighting. Here are some specs on the MAX16818, a single chip solution for efficiently driving leds from a 12/24 dc power source:

High-Efficiency, High-Power, Fast-Transient-Response LED Driver Controller
MAX16818 high-efficiency LED-driver controller

By comparison this bulb: link Has the same luminous efficiency, produces light with similar warmth, costs about 100 times less per lumen, and screws into a normal lamp.

Maybe when the prototype type stuff comes to market there would be some reason to convert to LED lighting. For now it only makes sense in flashlights and colored lighting. Anywhere else, it's an expensive gimick.

Lower watt compact fluorescents do not compare favorably with leds in terms of efficiency and many are only 1/2 the price of leading edge leds:

2-3 watt compact-fluorescents

Ok, so led lighting hasn't hit the mass market yet in production quantities sufficient to bring the price down. But I would bet on it running past other lighting technologies in the next few years.

[OldSprocket]

Notably, most of the listed LED bulbs also produce quite cold light.
.
.
.

I use a LED array of white, amber, red, and green to produce a more home-like tone. (Red and green are actually redundant with the amber in there, but it's festive!) The array above me cost just about $100.

WARM WHITE IS GROWING. I'm ready to add some 3000k bulbs from LEDtronics. Here's a link to a 120V 40-LED cluster.

LEDs are primarily a directional light source. Comparing them to incandescent bulbs will put LEDs at a disadvantage every time. I put light fixtures where LEDs create pools of light for various activities. This approach is also recommended by Christopher Alexander in his "A Pattern Language" about ways to make buildings more comfortable for people.

[halcyon]

Some facts:

Best LEDs (not LED bulbs, but single leds) are now at c. 80 lumen/watt in mass production.

Best researched (announced) LEDs in labs are now in the range of 150 lumen/watt with target being 200 lumen/watt for next year (Nichia, Japan). These are NOT the same as mass production LEDs

Best LED systems (like a bulb in a 120V standard fixture) has much lower system efficacy than single leds. The best ones in mass production now operate at c. 50-60 lumen/watt.

Standard photopic Lumen/watt is not the best measure for human usable illumination efficacy.

You need to factor in the retinal sensitivy distribution. A good rough measure is so called scotopic luminous power. One can calculate this from the spectral distribution of a light source, like a LED or a CFL lamp. This measure tells you how much of the emitted light your eyes truly can use to see things properly.

The best LEDs (efficiency and scotopic luminous power) are VERY expensive. This means that you can't buy them installed in a $10 LED light bulb.

You can buy the cheaper (less efficient) and worse spectral distribution (lower scotopic luminous power) LEDs in LED light bulbs, BUT currently:

1) they have lower lighting efficacy than best of CFLs when measured in lumen/watt (or about even)
2) they have lower scotopic luminous power than best of CFLs

When you combine 1+2, you get significantly less usable human luminous power for the same amount of energy.

Now, don't get me wrong. LEDs are fantastic and they have been and are still improving in strides, BUT we need:

- fixture efficiency to improve for LED systems
- highest efficiency LEDs (150+ lpw) come to mass production
- mass production to put down prices A LOT
- fixture systems to start moving from 120V/240V/AC to something more optimal for LED lighting
- people to get used to "cold" spectral distribution of white LEDs, which provide the best luminous power/watt for human viewers

All of this will still take a few years (i.e. more than two), the last one might take a lot longer.

I'm all for LED lights myself and they have bright future, but don't go into reading all sorts of non-connected information and believing that LED lights are now the savior of the world.

Then again, do not let this stop you from installing the best of CFL or LED light bulbs. They are much better for energy savings that incandescents. I only have one non-CFL/CFL in my home (a halogen) and that is a "mere" 30W bulb on a desk lamp for color critical work (CRI 99).


regards,
halcyon

PS Fairly up-to-date best mass production LEDs info at:
http://members.misty.com/don/led.html

[ChumpusRex2]

Some facts:
Standard photopic Lumen/watt is not the best measure for human usable illumination efficacy.

You need to factor in the retinal sensitivy distribution. A good rough measure is so called scotopic luminous power. One can calculate this from the spectral distribution of a light source, like a LED or a CFL lamp. This measure tells you how much of the emitted light your eyes truly can use to see things properly.

I think it depends on what you are trying to achieve.

Lumens are already adjusted for retinal spectral sensitivity, for photopic (normal) vision. Thus lumens are a good measure of luminous output under most circumstances. By extension, the lumens/Watt is a useful measure of efficacy.

The value of scotopic luminous intensity, is only useful for very-low light intensity. Typically, illumination levels of 1 lux or less fall into scotopic vision (night vision) - this is roughly equal to the light intensity, outside at night at half-moon.

For such situations, e.g. low-power flash lights the scotopic luminous efficiacy is more useful.

However, this level of lighting is useless for a domestic setting - you have no color vision, nor central vision at this light intensity.

[SolarDave]

These lighting panels seem to have reached the same lumens/watt as fluorescent - and are simple devices that have been engineered to be installed in standard locations. I just found them - I wonder how many other "small" companies have technologies like this we don't know about.

New Wave in Lighting Technology