While I certainly dream of building a true passive house, it is much more reasonable to follow the Pretty Good House approach, in it's current 2.0 version described here: https://www.prettygoodhouse.org/pgh-20
As with most engineering efforts, the last 20% of optimization tend to be costly. But covering the basics (mainly around insulation and air-sealing) has a huge impact already without increasing upfront costs by the same ratio.
Also the wall/roof assembly needs to match the climate for the region, mainly because of the dew point and how it relates to temperature and moisture differences between inside/outside. https://en.wikipedia.org/wiki/Dew_point
As with most engineering efforts, the last 20% of optimization tend to be costly. But covering the basics (mainly around insulation and air-sealing) has a huge impact already without increasing upfront costs by the same ratio.
Also the wall/roof assembly needs to match the climate for the region, mainly because of the dew point and how it relates to temperature and moisture differences between inside/outside. https://en.wikipedia.org/wiki/Dew_point