Fluorescent heating

And not high at the same time?

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The 4 foot T8 (1 inch diameter) ones are the most efficient common size, achieving in the 90's of lumens per watt. They mostly are rated to produce 2800 lumens from 32 watts at 50-60 Hz, and a couple losses are reduced (especially, the anode fall - most of which is oscillatory at a few KHz - is nearly eliminated) by use of high frequency AC from electronic ballasts.

I can't find an LED in the Digi-Key online catalog achieving more than

91 lumens/watt.

- Don Klipstein ( snipped-for-privacy@misty.com)

Not too long ago I looked at what was published in the website of DOE's "Caliper" program. Just a few LED items were achieving so much as 60 lumens/watt. A couple LED fixtures achieved about that much. HPS fixtures failing to exceed that must be either using 35 and 50 watt lamps (least efficient wattages of HPS) or be poorly designed.

Metal halide fixtures with lamps at least 100 watts gotta have something wrong with them to fail to deliver 60 lumens/watt.

- Don Klipstein ( snipped-for-privacy@misty.com)

Those are laboratory prototypes, not production units.

Most spiral CFLs for home use are rated 2700K and CRI of 82.

- Don Klipstein ( snipped-for-privacy@misty.com)

Most household incandescents have color temp. 2700-2900 K, and have CRI of 100 by definition. The 100 watt 750 hour 120V A19 has a color temp. of

2865 K according to Kodak.

(Though their figures for daylight sources appear a bit high to me. They say 5800K for direct sunlight in midsummer - and the color of the sun's light would have to be not yellowed at all by the atmosphere for that to be true. The color temp. of sunlight in outer space is a bit less. I suspect they are stating effective figures for usual films, including the ability of the film to react to UV.)

- Don Klipstein ( snipped-for-privacy@misty.com)

100 - according to the definition of CRI, especially the most-usual color rendering index, which is Ra8. Usual incandescents have CRI of 100 by definition.

- Don Klipstein ( snipped-for-privacy@misty.com)

All this at a fraction of a price, for the time being. But in a wastly more convenient form factor (LED). Leds do open up lots of possibilities for the future.

Thanks, very "enlightening", its nice to have some solid numbers at hand.

M

Then something decidedly weird is part of the specification. How could everything from heat lamps at about 1500 K color temperature to ultra hot blue-white plant lamps at about 7500 K all have a CRI of

100? The spectra are nothing alike. Nor do the same objects illuminated by these sources look the same. "What's up with that?"

CRI is by definition 100 for daylight/sunlight sources when color temp. is higher than the incandescent range, and 100 for incandescent sources when color temp. is in some sort of "tungsten incandescent" range. A wide range of color temperatures has capability of achieving CRI of 100.

Other light sources are compared to either daylight/sunlight or incandescent of same correlated color temperature. Deviation from daylight/sunlight/incandescent (depending on correlated color temperature) in rendering hue or saturation of any/all of 8 particular "Munsell colors" detracts from a score of 100 in the "Ra8" CRI.

- Don Klipstein ( snipped-for-privacy@misty.com)