Very interesting topic!
I currently live in an apartment on the top floor (with a flat roof) and windows without shutters. I only have internal blinds, which of course hardly help. It gets uncomfortably hot, even though all the windows face roughly east.
Over the weekend, I laid the floor panels in the attic and worked on the opening for the pull-down ladder. Until then, the roof only had a foil covering. Around 1 p.m., it became quite uncomfortable and eventually affected my circulation, even though I had drunk plenty. I don't want to know how hot it was under the foil. I've never sweat like that in my life.
The house has a lot of window area on the south side, also a large window on the east side in the living area, but none on the west side. The gabled roof has a substantial overhang to the north and south (in the northern gable, we are currently planning the intake of fresh air for the [Kontrollierte-Wohnraumlüftung]). We are getting really "thick" glazing, a total of 24 mm thickness spread over 3 panes. In addition, "insulated" aluminum shutters – whatever "insulated" means or achieves here. I'm curious whether we can keep the ground floor at a comfortable temperature in summer, also in combination with the operation of the [Kontrollierte-Wohnraumlüftung].
The ceiling between the upper floor and attic will be insulated, and the entire attic itself will also be insulated, as the heating system will be installed there. Here too, I am curious about the effect. For the attic, we are planning 2 windows controllable from the upper floor, which can be “programmed” so that the heat can escape from the attic at night by creating a draft.