On 12 July, 18:45, wrote:
Tim Streater wrote:

Further, 5 of them, drawing 60W in total, will also I assert emit less
heat than a single tungsten, because more of the energy supplied goes
into producing light, and less goes into producing heat.

Less, but not much less. One lumen is 1/683 W. According to
http://www.mge.com/home/appliances/l...comparison.htm, a good
incandescent bulb can generate ~20 lumens / W, so to a first
approximation *zero* electricity is turned into light.

A good CFL can generate 68 lumens/W - but that still means that 90% of
the electricity is turned into heat.

Except that all of the light will end up as heat anyway, where else do
you think the energy goes? *However I suppose there will be slightly
less heat in the lampshade.

The light will end up as heat - but as heat in the walls, furnishings,
and other absorbent surfaces around the room. However, as noted
above, even with a really good CFL (or even a high pressure sodium
street light), nearly all the electricity turns straight into heat.