passive solar is the same concept the tribes in Brazil used in their walipini
design and not limited or exclusive to the Chinese culture
my water table gets near surface so instead of digging down Years ago, I built a fairly large wofati
greenhouse .Made it like a keyhole garden with approx 140 deg. of corrugated glazing to the east and south . Had to tear it down as it hindered drainage. Looking for pics.
I agree for commercial purpose radiant floor heating would be best but as I understand it, the OP just wants to grow a few plants and veggies and doesn't want to break the bank doing so.
my set up that you see cost me 40 bucks for the heating mats lights and fan and only 6 bucks a month to run.
I'll make that up in e.coli free lettuce .
You grow any food Crushin?