In article .com,
"gmw" writes:
I have just used a photographic exposure meter to compare the light
output of a CFL bulb with various pearl light bulbs.

The CFL is a 20W bulb claimed to be equivalent to a 100W bulb. It has
had about 1 year of evening use.
Its measured light output is a little LESS than a 60W 2000h pearl bulb
rated at 555 lumerns, and ~40% of a 100W 2000hr bulb.
Power ratio for the same light output is thus 1/3 not 1/5. This is a
66% over claim in this case.

The small print on the CFL package says it is equivalent to a 1000h
"soft colour" bulb. This is presumably much lower efficiency than
normal pearl bulbs. This claim is therefore presumably accurate but
misleading.

This is a well-known problem here, and unfortunately, it makes many
peoples' first experience of a CFL a poor one which they choose
not to repeat. Softone lamps do indeed have a lower light output,
so this is marketing bull**** at its worse, particularly as rather
few people use Softone lamps.

My normal advice, often repeated here, is to use a factor of 4
between a filament lamp and a CFL, and that would be a CFL with
exposed tube (an outer bulb loses some more light). Reflector
CFL's do much worse, because a folded tube is a really bad light
source to try and reflect in any direction without significant
light loss. (The one exception here is the GE Genura R80, which
at 23W produces more light than a 100W flood lamp, but it uses
a significantly different technology from standard CFLs.)
The other problem you can find is that the different size/shape
of the CFL may mean it's light source is not in exactly the
position the luminare expected, if it was designed for a filament
lamp.

Having replaced several 100W pearl light bulbs with "100W" CFLs, we
have reverted to pearl in all but one room.

Look for 25W CFLs.

These misleading claims must be understood and ruled out. CFLs are not
yet ready to replace conventional bulbs. The calculated efficiency
gains are greatly exaggerated.

They are, but you fell into the marketing trap which most CFL
first-timers fall into. Try to move on without dismissing the
whole technology.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]