Double pane and double glazing glass have excellent thermal properties, however, with the tree transpiring at night it would be muggy in there I'd assume. This is probably why it very tall and narrow so most floors are habitable.

Privacy is not an issue as it's in the middle of nowhere.

The kitchen, bathroom, shower, toilet are all ground floor. I assume the living space is the floor above with lounges and such which you could add a bed too. It's designed as a lodge for not permanent habitation. Think of a small shack, log cabin to sleep the night, then spend the entire day outdoors, fishing, hunting, etc.