Indeed and I wasn’t excusing a top “vent” just explaining why people use them.
I’m a great believer in insulation and my wooden hives are surrounded by PIR. Most of the hives are poly though which I ,and seemingly the bees, prefer.
I can’t see anybody hiding their Tung oiled boxes under anything.
I just read this thread and did not see a clear answer for my situation…
I live in South Florida…I have two hives on my second floor covered balcony…Each hive has two Brood boxes…The hives are covered from rain and get some morning sun…I am a bit concerned about high temperatures in the hives…
The hole in my hive covers are covered…and the bottom board has the plastic sheet inserted…Should I open the top hole (Screen it to keep them out of the open roof area) and remove the plastic sheet in the bottom board to help with ventilation? Should I leave the cover hole covered and just remove the plastic sheet to improve ventilation?
I see that there is no way for the bees to leave the hive from the top section, so I assume that a screen needs to be on the top hole to prevent them from building comb in the roof area…
Thanks for any direction you can give here…
I think you found no clear answer, because there is no single answer. If you remove the coroplast sheet, that will impair ventilation, because it reduces the effectiveness of fanning by the bees. I would leave in place. They will probably be OK with the hole in the inner cover closed, but I like to duct tape a piece of #8 hardware cloth (you can use fly screen) over it in summer to let the hottest air out. You may well find that the bees propolis that up, in which case you know that they prefer it closed! 
And I went with a top entrance (2in wide) that I cut into my Inner, so they will get warmth and moisture out the top.
Well, according to the Thermohive that has been touted on a few threads here if you have a hot hive you have no varroa 