The thing is, for the retrofit case ("current house") it's a different ballpark of complexity. The thing is, there's no technical question about Ph levels - ALL houses should be built to that standard. The challenge there is political.

The technical challenges are in retrofit.

You might find Energiesprong (http://energiesprong.nl/transitionzero/) of interest - basically factory manufactured walls with joinery, move to site, crane on.