Florida in the winter was quite close to perfect. Or Spring in Maine, just before blackflies.

Foam comes very near perfect as an insulator. But I believe the walls on our homes need to multitask. Just as there is no ideal vehicle, truck, car or somewhere in between, our walls fall into the same dilemma. Indoor air quality is one factor. Thermal mass comes into the picture, foam has none. Comfort levels of the individual varies, this is a determinant for the wall system used.

Tim