There's a lot to be said for traditional construction methods. People all over the world have already devised excellent solutions during the course of history. Case in point, anyone who's ever travelled in the Sahara desert is probably well aware of just how cooler and more comfortable the older mud brick buildings are opposed to the more "modern" concrete and brick houses that are now becoming much more common.

It doesn't take too much effort to adapt these solutions to our particular needs and modern technology. But trying too hard to come up with something "new" too often leads to reinventing the wheel, I'm afraid. Also, few people building their own passive house nowadays understand their environment well enough to devise an optimal construction. The vast majority of us simply have not lived with nature as closely as our ancestors and don't know the environment well enough.

I've seen a guy who built a house almost entirely out of clay, straw and a little wood. It might have been just perfect for an arid climate but he built it in a fairly cold area with plenty of rainfall. The insulation is still excellent but the rain and snow degrade the mud walls to the point where they require serious repair at least once per year. Not that the repair itself is costly but it needs to be much more frequent than most people with a reasonably modern lifestyle could tolerate IMHO. On the other hand, had the gentleman in question only looked a bit closer at the traditional houses in the area (mostly wood), he might well have selected a different design much more appropriate for his region.