I just added a link to Gouin (Go-In) Green a process blog where some folks are building a SIP modular house. The house is rather vanilla but the blog is full of excellent information and $ #'s which I always appreciate. It looks like they actually used Alpen Windows which are super good and they talk about how they justified the extra cost. There is also a long discussion of radiant heat in a super-insulated house in the Features section