After a bit of back and forth with the window people (to get them to pony up some official-looking stats on their window performance), I have my efficiency rating:
Better than I expected – my gut feel had been somewhere in the 8.5 range, mainly because of the size of the glass in the living room, the west-facing aspect of some of that big frame, and the east-facing narrow windows in the bedrooms.
I think if I’d done this assessment earlier in the process (instead of just ticking the box for certification) I might have tried to tweak the design to get it up to 10* just for bragging rights, but I’m more than happy with 9.4* as it is.
