Conall had his home designed with in a 'manly traditional' style by an architect but he has whole sections that he rarely uses. This reading nook is only used by him when he wishes to sit in the sun or use the best natural light in the house to examine something.

As every good professor knows direct sunlight fades and damages artifacts and books so he shelves are always bare.....then Sasha finds it. And incongruous things like a bright rug and garish tinsel get inserted. Later she starts putting her 'treasure (junk)' in there once her bedroom has no more space. She also adds fake snow because it never snows where they live. XD

I tried to link the window design back to a previous image I doodled of his home