> Is the light noticeably more attenuated through 4 panes of glass compared to 2 or 3?
I don't notice a difference now that I have two double glazed windows on top of each other (kobla vindu - I don't know the English word for it), I'll include a picture here:
https://spesialvinduer.no/wp-content/uploads/2019/08/Skaara_...