Fascinating! Well written article that educates us on a topic for building and other applications. Thanks for posting that. Since I'm no rocket surgeon myself, I'm trying to apply this concept to a mostly unheated building in a predominantly cool, damp climate that I'd like to insulate. Am I correct in assuming less is more for permeability on the inside of the building? If I use Kraft-faced insulation, will that be appropriate for something that may have cool, damp air that I rapidly heat on occasion? Note: The exterior will likely be some form of Hardi, either plank or shingle, sheathed with plywood, and the building will be wrapped with builder's felt/tar paper (hope that's the correct terminology.) This also makes me wonder if for a building like this, I should have some special venting for interior space while it's closed up, not heated, and going through exterior temperature swings.