It is hot on Saaremaa these days. Even hotter inside the boat now that the windows are getting mounted and the amout of open holes in the hull is going down. Lots of people are working inside so we actually need fans to keep the temperature reasonable.
All windows are double glassed, to avoid condensation on the inside when sailing in cold weather. They are made from hardened float glass. The thicker outer glass is solar controlled, which will reduce the amount of heat gathered in the deck house about 50% when are sailing in warm climates. I do think the deck-house will still be pretty hot, since it has a lot of windows. But at least with solar control glass it is better. And there is a ventilation hatch on top to help with letting the warm air out.
There is a thick frame of filler around the windows, which will absorb the difference in thermal expansion between the glass (which changes dimensions very little with temperature) and the aluminum (which changes a lot).
The top side windows are recessed 25mm into the hull which will protect them in case of uncontrolled contacts with other objects, like docks for example…