DIYbanter - View Single Post - Are name-brand low-energy fluorescent "Green" bulbs any brighter thanstore brand?

Don Klipstein

In ,
wrote:

Don Klipstein wrote:
In ,
wrote:

Don Klipstein wrote:
In , Dave Garland wrote:
Well, they should be brighter than a 40W incandescent. Check the lumens
rating, that gives you a number to compare. A typical 100W incandescent
is around 1600-1700 lumens. Walmart doesn't seem to give the lumen
ratings on theirs but a Sylvania CF23EL is indeed rated for 1600 lumens.

It may take it a few minutes to reach full brightness.

But it seems like all the companies cheat on the "equivalent to" rating,
if they say "equivalent to 100W" I figure it should be a bit brighter
than a 60W.

My experience is that non-dollar-store CFLs marketed as equivalent to
100W significantly outperform 75W "standard" 750 hour incandescents rated
1190-1210 lumens.

Lumen output drops quite a bit throughout a CFL's life, whereas
filament lamp fall in output is much less. Consequently to get a real
equivalent one needs to start with higher lumen levels than the
equivalent filament lamp.

CFLs when aged to 3,000 operating hours have about 10% (maybe a bit
more) loss of light output compared to that at 100 hours (industry-
standard break-in period, immediately after which their light output
is "officially" determined).

So the 1600 lumen "100 watt equivalents" can fade to about 1400-1450
lumens at 3,000 hours, and fade a little more to maybe about 1300 lumens
if and when they get to 6,000-8,000 hours or so. Even that is still a
bit brighter than "standard" 75W incandescents.

If your home is one of those where the line voltage is on the high side,
then incandescents will have much-enhanced photometric performance. Light
output from a CFL may be merely roughly proportionate to line voltage,
while incandescents have light output typically proportionate to line
voltage to the 3.4 or so power.
So if you hit a 1190 lumen 75W 120V incandescent with 124V, then you get
about 1330 lumens from that incandescent. In homes with higher line
voltage, incandescents get a "disproportionate boost" in performance - if
you are not bothered by them not lasting as long as they should.

Many of us now use CFLs rated at 10k hrs mean life, so many of them
will go on to well over 10k. Using your figures and extrapolating
wildly, at 15k hrs they will have lost somewhere vaguely in the region
of 50% output. Not that bad in most cases, but yes big drop.

As it turns out, the "halflife" increases a little as the lamps age.
So ones that make it to 15K hours have more like 70%, maybe 75% of the
light output that they had at 100 hours. I have actual experience in an
apartment building that had CFL hallway lights and some of them lasted
that long.

I have seen a few CFLs faded to about 60% or 2/3 or so of their original
light output, after over 2 years of continuous operation. Most don't last
that long.
If one makes it in home use past the 6,000-7,500 operating hours that
they used to be rated for, then I think its owner will be quite happy with
it in terms of actually achieving the long life that they are supposed to
have. My experience seems to support a figure more like 4,000-5,000
hours, due to average ontime less than the "industry standard test
condition" of 3 hours, and average ambient temperature around the lamp and
ballast housing hotter than the "industry standard test condition" of 25 C.

- Don Klipstein )