LED bulbs are coming down in price - do i want warm white or cool white, and why?

[hedgehog]

I'm thinking cool white in order to get accurate colors, but I'd like some input one way or another.

[northoftheborder]

1. I want input on this also.

[NYC_SKP]

2. If you want efficiency, go with cool white.

I'm addicted to LEDs and have friends in the industry. I'm a geek.

I was even given a Saturday tour of the manufacturing facility where the epitaxy of chips and the testing occurs.

Cool thing to do: accidentally break a Phillips or other modern lamp (the technical term for bulb) and you'll find that the true color emitted is blue.

Phosphors in the lamp lens re-emit the light into the warm range, but the natural range is in the UV-blue range.

The photo below shows how you can pry off the amber part to reveal the LEDs.

[woodsprite]

3. I've driven hubby nuts looking for a good warm white.

It's the closest to natural lighting and easier on the eyes than some of those really cool white bulbs. Too warm or too cool and you greatly affect your perception of surrounding colors. Our family does a lot of art, so it makes a difference to us. You really just have to try them, I've ended up with a few too warm whites (look almost yellow).

The other thing that bugs me are the bulbs that take a long time to come on once the light switch is flipped. I hate shopping at Walmart, but we did find a decent, faster responding, "soft" white bulb there. I think we've replaced about 70% of the bulbs in our house.

We used the really warm color in our outdoor coach lights. I thought the yellowish look may deter bugs without putting one of those yellow bug lights in. So far, it seems to be working fairly well judging by the small amount of spiderwebs that have reappeared.

We've wired our own for some art projects and found that 3/5ths warm to 2/5ths cool is a good ratio.

Here's a good graphic showing the major range of whites:

[snappyturtle]

4. Here's the easiest way to discover what's best. Keep in mind the

function of the room when making a choice.

Google: warm white vs cool white led

Then click on Google images for examples!

I prefer warm white in m living area...it's just what it says, "warm".

[TreasonousBastard]

5. You probably want a bulb with...

3000-3500K and a CRI of 90 or above. Of course, hardly anyone bothers to tell you what the actual color temp or CRI is.

CRI, or Color Rendering Index, is a term from the fluorescent days where 100 is 100% rendering of colors-- natural light. When I worked for Duro-Test I sold fluorescents that went as high as 95% when the typical cool white was around 75% and warm white in the 50's. Cheap "Daylight" fluorescents were just kinda blue and rarely had much red in the color balance. More expensive ones, like ours, had a good color balance and were used in art shops, textile production, and other places where accurate color was needed.

5000K is about the color temp of sunshine in a clear sky. 7000K and up is "north light"-- the sky without the sun. An old incandescent lamp is around 2700K, with halogens a little higher. Photofloods were 3200-3500K.

If they don't give you the color temp on the box, there's no telling what else they don't give you, so pass 'em up.

I've found the most pleasing light to most people is a color temp of around 3000K or so, since it's closest to the light bulbs we're used to. Next most pleasing (and my personal favorite) is 5000K. In that picture in Post #3, the "natural white" one would probably be the best bet.

But, there's that CRI to worry about, and hardly anyone publishes that- they think it just confuses people.

BTW, if you compare the lumen output per watt, you'll notice that LED's aren't really that much cheaper to operate than CFL's at this point, and until they get much cheaper and increase the light output, they are actually significantly more expensive.

[NYC_SKP]

6. "Cheaper to operate" needs to take into account lifespan.

I know you know this but others don't appreciate that CFLs crap out early and LEDs don't.

In fact, LEDs can't even express their life span well because, if you do the math, testing anything for 50,000 hours takes a few years, during which time new generations of the technology will have come and gone.

[TreasonousBastard]

7. Sure, and some cheap cfl's...

never make it to the advertised life. May not even make it to next week.

But, the whole lifespan thing makes little sense. Leaving a lamp on for 12 hours a day means it will take close to 12 years to get to 50,000 hours. You'll move, break the thing or get tired of it before then. It only makes sense in a commercial space where you pay a guy 15 bucks an hour to get to those 30' ceilings. And, yeah, in that timeframe all sorts of new things will come out and it's easier to decide to get new if your old one burned out. Note that if an equivalent cfl costs a buck and lasts a year while the led cost $12 and lasts 12, it's a wash.

And, yes, lifespan is median lifespan, meaning half will last longer and half less. To get that 50,000 hours now, you can torture the things, take them apart and examine them under a microscope, compare them to similar installations, and apply sophisticated statistical formulae to guess how long they'll last. But, it's still a guess.

LEDs are unquestionably the future and there's no good reason, except maybe initial cost, not to buy them now. I just don't like to overstate the case.

[hedgehog]

8. Given the life span, i can see the day coming when LEDs are given as wedding presents,

and when you buy a house, you specify that the previous owner leave the bulbs!

[seveneyes]

9. Get the adjustable RGB ratio bulbs

I'm not sure who is selling them but independently adjustable brightness diodes will give you all possible colors.