We designed and built our own passive solar straw bale house back in the 90's. It had greywater system, composting toilet, earth tubes for cooling, and wood stove water heating backup. We moved in while it was still a shell so we could work on the inside during the winter. At the time we lived in an old mobile home that had zero insulation left in it, so this was definitely an optimal situation to live in an unfinished house versus an old trailer! At the time we had the finished shell for $20K.
I wrote a book on our experiences and instructions on how to design a passive solar house, and photos of how we built our straw bale house (it was load-bearing at the time, but today I would do post-and-beam). Feel free to learn from our mistakes instead of making your own!
Book title is available on Amazon:
Cheapskate's Passive Solar Home Design for DIY Straw Bale or Green Building:
Thrifty Ways to Barter and Find Cheap Used & Free Materials on a Frugal Budget
https://www.amazon.com/Cheapskates-Passive-Solar-Design-Building/dp/1717523536/ref=sr_1_6?crid=AHKVTBWFQRGU&keywords=sharon+buydens&qid=1655416712&s=books&sprefix=sharon+buyden%2Cstripbooks%2C248&sr=1-6
