The house wasn't really pushing any "new technology". All fairly regular stuff that's been around for quite a while now. As far as I could see it was based on pretty basic but sound and well-proven concepts - airtight construction, good insulation, decent thermal mass and thoughtfully placed glazing and shading.
Part of the reason why things like the windows were so expensive and had to be sourced from abroad is that there is not a great demand for them here, because the regulations in this country are not as strict as in others. The way to change this is to gradually tighten our regulations, and make sure they are enforced. Which is what is happening, slowly.
The air-tightness thing was presented as if it was somehow radical: it's not particularly, they were just going above and beyond what would be necessary to pass building regs. Air-tightness standards have recently been introduced into the regs, and tests like the one they showed with the big fan have to be carried out on new-build housing now.
I actually thought it was considerably less ostentatious than most houses you see on Grand Designs. They had chosen to spend their money largely on making sure it was super-well insulated. I think that is better than spending it on blingy kitchens or wanky lighting systems.
They also spent a fair bit of their money on the arch, of course, which was basically a folly and for fun. It was kind of experimental but not in a particularly useful way; you could have achieved much the same result with much more straightforward construction methods. But I had some sympathy with his desire to do something a bit unusual purely for the sake of it.
Design-wise, I thought the end result was pretty good. Better than I expected. It looked like the interior worked quite well - I was a bit sceptical when they showed the plans at the beginning because I thought there was a danger they'd build a beautiful self-supporting arch and then render it pointless by cramming a load of stuff underneath it.
One of the nicest projects I've seen on Grand Designs for a while.
Kevin McCloud annoys me slightly more each episode though.