Stefek Zaba wrote:

The Natural Philosopher wrote:


Think that incandescent bulbs are about 1% efficeint, so 60W bulb is
about 59.5W heat.

I think you know better than that! In order-of-magnitude terms,
incandescents are about 10% efficient.

No. They are not anything LIKE that efficient.

1% is a typical figure I believe with halogens maybe 2%.


Think the energy ones are about 3 times trhat - so maybe 3 rtimes as
efficeint, at 3%, so 20W in abouty 19watts out...


The ratio's about right - compact flourescents 3-4 times as efficient
(though the mfrs like to pretend it's about 5 times) - but that gives
actual efficiency as 30-40%. Of course, as that light hits other
surfaces (whether the lightshade or the things it's illuminating in the
rest of the room), much of it gets absorbed, heating up the absorbee. As
Kenneth Williams nearly said - "entropy, entropy, they've all got it
entropy" ;-)

I was wrong on fluoros - they are - or should be - around 15% efficient,
but I stand by teh 1-3% off incandescent.

I suspect enbergy efficent bulbs are no way as efficient as e.g. factory
strip lights.