LED manufacturers

[Fredxx]

A 5W LED lamp does not produce 5W of heat. An appreciable proportion of that 5W input power is converted to light.

[Fredxx]

You snipped: However where colour is perceived the CIE standard curve is used to convert radiant energy into luminous (i.e., visible) energy.

This might assist:

No, Lumens is a total output from a source. The sun has a radiance of

3.6 x 10^28 lumens.

At sea level on the equator this gives 126k lumens/m^2. Your figure of

93k is likely to be 93k lux. A lux is a lumen/m^2

I got the figures from:

The science and numbers around light can be confusing depending on whether you look source side or viewing/detector side.

[The Natural Philosopher]

'An appereciable proportion' being like what? - 20%?

LEDs are better, but still well over half - probably >3/4 overall - of the input power goes up as heat.

[tabbypurr]

80 or 100 lumes/watt means over 4W of that 5W is heat.

NT

[whisky-dave]

But the spectra for tungsten, florsecent and LEDs are differnt and are differnt to the human eye.

So it's not as simple as watts = brightness is it.

Niether of which is relivant and does not equal watts of power.

So why not calculate that in watts then, because you can't equate them that easily.

No we haven't

Luminous efficacy IS NOT the same as efficiency note the diffence in spelling.

[whisky-dave]

No it is NOT.

Lumens is the quantity of visable light. (for humans)

So.

what figure of 93k ? I've said 30K UK sunny day but can be up to 100K .

for most it's from the viewing side.

is a measure of how much luminous flux is spread over a given area. One can think of luminous flux (measured in lumens) as a measure of the total "amount" of visible light present, and the illuminance as a measure of the intensity of illumination on a surface.

So if you want to know how much visable light is given out yuo check the number of lumens rather than the wattage.

[tabbypurr]

There must be some topic you understand. Tell us what it is.

[whisky-dave]

Yes this is one of many do you know anything.

Are you really saying you judge light output by the number of watts ?

[tabbypurr]

oh dear

NT

[whisky-dave]

You'll be telling me next that horse power is also an indication of brightness.

[tabbypurr]

No I don't intend to claim that. It's weird that you have a habit of arguing matters on which you have not learnt the basic concepts.

There is no point us continuing this discussion.

NT

[whisky-dave]

But I know more than you it'd be diffiocult not to.

So if you have proof I'm wrong post it or shut it.

So don't then. i.e you cam't prove I'm wrong can you.