Dan, Both Hardie Plank and a 3/4" and 1.5" insulating foam board are good options. There is also the choice of using Insulated Siding that is a custom contoured foam backer. It fits to the specificati ... read more
Abe nailed the answer for you.
If the windows are due for replacement, look for a window with offset glazing or an option of laminated glass inside the standard set of windows.
Dedicated STC windows w ... read more