Shouldn't this be physics class and if the diffuser is absorbing 5% of the light isn't their less light?
Walrus, you are missing the point. They are debating theory, not actual results.
Operating rooms, for example, use light fixtures that cost more than my toolbox.
Which has 0.0% to do with what people are actually using.
Cheap diffusers (you know, the kind we would actually be using) block a heck of a lot more than 5%, which you can test in seconds by actual light meter or actual visual testing.
Add a layer of dust, which covers my black tool boxes in about 1 day, over the diffuser surface and I suspect the drop will be 1% more.
Keep adding that and pretty soon the lights look like the diffusers in the local stores. About 10-20% covered.
Who in their right mind is going to climb the ladder 20 times, drop the diffuser, climb back down, clean it with water (we found soap left a film) then climb back up, and return the diffuser. Say every week or even every month.
Oh, by the way, cheap diffusers come apart pretty fast when you take them down even once every three months. Guess how I know...
Then there is the idea that a diffuser, a large upwards surface, will gather dust in proportion to round glass facing downwards.
Think about it.
We used to 'dust' the T12 bulbs in the stores about once every two years. We had to clean the diffusers every three months and that wasn't often enough.
Bulb facing down, diffuser facing up, for those that don't see it.
Diffuser rough surface, bulb shinny surface, for those still not following.
Oh, and don't forget the moths, flies, etc. that like to die in there. Every fixture is an entomologist playground.
5% loss is WAY less than real world, but again, we are not arguing the same point.
They are making theoretic points, like in Physics class. I am talking actually doing it.
So we are talking to different points.
In theory, anything can be proven.
Try the lights with, and without diffusers. See what you see.
Arguing is not useful.
Count the horses teeth.
For those that don't get it, old parable about Greek philosophers arguing about how many teeth a horse had.
After listing for three hours a old Arab leaves, comes back and gives a definitive answer.
The philosophers wanted to know his logic, his reasoning, his basis for his theory.
He told them 'I went to the stable and counted them'.
So of course they discounted his answer...
