Lighting 101, basic but...

[aesmith]

i.e. the heat output of a 60W CFL is nowhere near as much as that of a 60W incandescent.

By how much, do you reckon? I'd always assumed the same, but I suppose your reasoning is that more energy goes into visible light.

 

[JohnW2]

i.e. the heat output of a 60W CFL is nowhere near as much as that of a 60W incandescent.

By how much, do you reckon? I'd always assumed the same, but I suppose your reasoning is that more energy goes into visible light.

Indeed - as he explained in his next post:

AFAIK an incandescent lamp turns about 90% of the energy it consumes into heat, and a CFL about 30%. So a 20W CFL will produce, not as much heat as a 20W incandescent, but as much as a 7W one.

He is therefore suggesting that an incandescent lamp will generate roughly 3 times more heat than a CFL of the same wattage.

Mind you, as bernard pointed out, with a CFL the heat is mainly generated close to the base, not all over the envelope - so , particularly if it is installed 'base up', the heat will probably not be dissipated as quickly from a CFL. That might suggest that the base of, say, a 60W CFL would get hotter than one might expect (from 'heat watts' alone), but probably nothing like as hot as the envelope of a 60W incandescent.

Kind FRegards, John