If you want to learn more about this Balsa Wood material, go to www.balsacore.com
They produce 48' flexible panels of end grain balsa wood backed by a fiber mat. Used in an AC application, I'd guess it would have to be sandwiched between layers of fiberglass just like last-a-foam. I don't know how expensive it is and wonder how much it weighs compared to last-a-foam which is 4 lbs per cubic foot (a 4x8 sheet of last-a-foam weighs 4 lbs). Dave McCauley