We're doing passive solar, and the slab is the primary heat storage medium. I am planning on putting down a perimeter footing to well below the frost line. The slab will be insulated along with the footing walls.
Rick
Go to
Builder's Guides and check out the books for your geographical area. Joe Lstiburek from
Building Science Corporation wrote the books. I used his book for the framing and foundation details when i designed our house.
Our house is passive solar with a colored, finished concrete floor. We thought about a mono slab but how to insulate it? I think we used EPS rigid foam underneath and around the slab. The concrete is sitting in a tub of EPS. The edges of the tub are 1 inch EPS foam board which creates a thermal break between the slab and the footers. The bottom of the tub is either 3 or 6 inches of foam. I would have to check the drawing to find out.
Our house works very well. If the temps stay in the 60s as a high and does not drop below below the 50s the house stays at 75ish during the winter. It would do better but I put in windows based on the room and the view there of.

Each major room in the house has at least a 8x6, 12x6, or 8x5 window aka hole in the wall. I did NOT follow passive solar guidelines on the non south facing walls since we wanted the view, natural light and air flow. If the humidity is low we will keep the house open while the outside temperatures get to the mid 80s.
We would have had a longer two story house with the long axis running east/west but the cost of going up a story and having open space was too much so we went with a single story house. The two story house would have been more energy efficient I think.
We also thought long and hard about putting in radiant heat in the slab. But for our area it just did not make money sense to have it installed. We heat the house with a single wood stove that is supposed to heat an 1800ish sf house. Our house is 2400ish. The only time we need more heat is when the temps fall into the teens and 20s but that does not happen often to justify a second stove which we almost installed when the house was built.
I highly recommend the books in the links.
Later,
Dan