These are becoming far more common in Europe and as we move to better insulated buildings and implement the Code for sustainable homes we will need these too.

Wood is a great material for window frames and combined with a lamination of insulation become tremendous.

Foam.
On the question of window frames, with 30cm of "cavity" insulation, where abouts does the window frame go? i.e. just inside the outside skin? mid cavity with sleeves between it and the front and back of the wall.
Frank

Best place for the frame is fully on the outside of the inside skin.

There is a lot to be gained by insulating wooden frames.

The insulative laminae will have to be very cohesive - pressure from the compressed weatherseals and glazing gaskets will tend towards de-laminating a weaker layer.

I've been puzzling how to do this for a while. One answer - through fixings - if metal, wld be a thermal bridge. I ought to experiment with cork - must get a sample ...

Roger, I believe the cork is just glued in as per normal laminating because of the cold bridging, but you cannot just use any old cork, partly for the reasons you mentioned. As I understand it the cork comes in sheets of chopped up cork held together with binders of some sort.
We looked into this a bit a while back as we are making our windows from laminated oak and thought it would be a simple addition to the process, but you have to use a suitable grade of cork sheet and the right glues etc etc. I was struggling to get advice on it and it all seemed a bit new to get any meaningful info. Also the thermal performance of the cork did not seem very good and it was not cheap as I recall. It all seemed a bit complicated for very little gain, hence my comments above.
That said, I believe there are manufacturers seriously looking into this and there are supposed to be developments afoot. Possibly a bit early in the evolution of these products.
Bear in mind, my comments are made as a keen amateur, rather than someone who actually knows what they are talking about