Oh, that's one heck of a dirty window!Originally Posted by mde
A clean, single pane of plain glass will transmit 92% of the incoming light.
And, as a measure of light intensity, a footcandle is
the intensity of light received
by 1 square foot of a surface
that is 1 foot from a particular source of light.
So, since intensity goes as 1/r^2,
where r is the distance from surface to source,
I would say
the greater loss in light is due to distance from the lightsource/window,
not the window itself.