I,ve been debating your responses for several days now. I was convinced that I had devised the ideal construction,so i've been re-considering it.
All i'm doing really, is to build a timber frame house but with additional insulation and added thermal mass.
The hypocaust floor i'm adding is just for a bit of fun.
I can see the advantage of manufactured timber joists (OSB web) for walls and roofs, which would allow large amounts of insulation. Can such a constuction be built quickly and cheaply?
I,m going to visit the passiv house exhibition in Hannover, in May, so I hope to come back with all the answers.