It's actually designed quite brillianty. In the winter the sun is lower and it shines inside the house heating the concrete floor. The glass also has a special coating reflecting heat out on one side of the house, and reflecting it back in on the other side (So depending on the season/time of day). The windows are also ridiculously thick and expensive. I forget what the coating is called now too.I wouldn't want to heat that place, insulated glass or not.
Yeah he'll probably need to retreat the exterior probably every year or two... That's a daunting task.I love the open rooms, it's a real work of art. let's hope he keeps the outside looking good for many years, most people can't keep up with maintaining cedar, it's going to grey up.