OT Things you would not learn if the weather were not 40something below C....

I also studied architecture for a year (before I dropped out) and one of the things I do remember vividly was going onto sites with a builder every week. The walls at that stage were built, as you say, with a gap between the two layers of bricks with little metal strips between each wall. These strips has a kink in them, which would be placed facing downwards, in order for moisture to drip down and not seep through the next layer of bricks. This was done mainly on south-facing walls (we're in the southern hemisphere) an possibly isn't done at all any more, as standards have dropped. I'm sure it served as insulation too.

Air pockets are better insulation than anything solid, as heat is transmitted slower through air than through solid material. Probably the houses insulated with seaweed were done like that deliberately, as making a small gap is not as easy as no gap at all, and the seaweed disintegrating would serve that purpose.

We don't have quite the same need for insulation as people in Canada, but our temperature did go down to -9C this year. And since the time when a dog jumped through TWO of my windows in two different rooms, and took out not only the window pane but the frame as well, I've kind of been living outdoors!! Or it's felt like it.

Catherine