Actually, what I wrote was "My intention is to build to PassivHaus standards (or better) to minimise the energy input needed."
Unless you are actually using the PassivHaus package, etc, I'd suggest a much more careful wording; they're quite touchy about their trademark, I believe, and anyway you'll just confuse people. Why not say something like "build to standards similar to PassivHaus" or, as I do, just ignore the term altogether?
I have a similar project planned. Big differences are off-grid (primarily for similar ethical reasons which motivate some of your decisions) and high thermal mass in the form of a large water heat store within the thermal envelope of the otherwise thermally lightweight house. Similarities are no combustion, timber frame, high grade insulation (was going to be polyiso but met a possible builder (for the basic frame) who's into sheep's wool for walls/roof and shredded paper for the floor), airtightness + MVHR, clear undercroft over chippings (probably), tinkerability.
Something I've long decided against is UFH (except perhaps in the bathroom). Basically, the house shouldn't need enough heating to justify the expense.
I did avoid using the "P" word in the thread title, for the reasons you give, but I'll admit to falling into the trap of using the word as a short cut to quickly refer to the core features we were aiming for. Your comment about the trademark and protection that this organisation apparently protects somewhat vigorously makes me more convinced that they see it as an income-generation scheme, rather than as a step forward in housing standards. With more than 30,000 houses having been built to this standard now I'd have thought that they would have more than recovered the modest development cost of this tool.
The annoying thing is that prior to finding this plot we'd been thinking for many years of building an earth sheltered house. The buried archaeology put paid to that idea, though! Energy efficient earth sheltered houses predate the invention of the PassivHaus by a considerable period, yet embody many of the same core principles (high insulation values, airtightness, very low heating/cooling energy requirements). As far as I know, no one has yet tried to turn earth sheltered housing principles into a money-making scheme, yet...............................
Your project sounds interesting, what sort of foundation system are you planning on using?
Jeremy
