The East and West walls are the half-gable ends 12' wide by 12'high at the ridge. The East wall has french doors and the West wall is shaded in the afternoon. The north Wall is an "interior" between the shop and an un-heated garage. The South Wall has windows and an access door but is protected by a 2 1/2 foot roof overhang.
This is why I only went with the Radiant foil in the ceiling and will use fiberglass batts in the walls.