Excellent, thank you. If I don't have a better R-value suggestion by early next week I'll give that a shot. Cardboard is noted as R 3-4 at http://inspectapedia.com/interiors/I...lues-Table.htm.
My co-worker also advised me that glass is a poor insulator and is unlikely to be better than doubled oven bag material. I found 1 site noting the doubled bags as have an R-value of 3-4, better than single-pane glass of 0.14 (if I'm reading it right).
Bookmarks