Don't fool yourself. Lumens is the official international standard.
The Process or setup is what you are talking about before light is
measured. And what process did you use to determine the '90%' from
paint. What paint color and what paint surface and .... who cares
really. Just say a lot of light and you would be ok.

I have advanced work in Physics and Electronics.

Martin

On 11/13/2016 1:15 PM, dadiOH wrote:
"-MIKE-" wrote in message
news
On 11/12/16 12:42 PM, dadiOH wrote:
"Gramps' shop" wrote in message
...
Need to add some lighting. T8 or T12? Probably going with 2-tube
4 footers.

More - probably - than you'll ever need/want to know (downloads a
PDF, takes a while).
http://apps1.eere.energy.gov/buildin...offer_2013.pdf

To paraphrase it, if you want to save electricity, use LED; if you
want max light, use flourescent (use electronic ballast)



My actual experience would contradict that.
Lumens are lumens.

That's true. It is also true that T-8 replacement LEDs emit fewer lumens
than do T-8 fluorescents.

However, the fluorescent lumens are coming from all areas of the round tube
while the T-8 replacement LED lumens are coming from maybe a 100 degree area
of the tube which means that the light falling on an object may be very
similar for both.

In reality, "lumens" is not a good way to measure the real life
effectiveness of illumination. For example, if one uses diffusers on their
fluorescents they are immediately losing 1/2 the light output from the
tubes.

In my shop, the fluorescent lights are recessed into a cavity between the
trusses. That cavity is painted white which reflects about 90 % of the
light hitting it which means that I am capturing some of the lost light ffom
the fluorescents that is going up/sideways (a more reflective surface could
capture more). If I were to replace them with LEDs, my shop would be less
bright.

My shop is brighter than daylight and I'm using less than 1/2 the energy
of fluorescent tubes.

How did you measure the brightness? Also, how bright and what is
"daylight"? Is it sunlight? A light cloudy sky? A dark cloudy sky?