A superinsulated sunroom might sound like an oxymoronic idea, but it is not. Just use triple glazed windows and thick foam over the wall framing and roof
—David Joyce has been doing exterior insulation retrofits longer than almost everyone in North America. He cut his teeth doing "deep energy retrofits" for Building Science Corporation more than twenty years ago, when the idea of exterior insulation was radical and new. Now it's in the code.
A thermal break and solid backing puts the window on the outer face of a thick wall. Now, there's room on the inside window sill for cats and bowling trophies