hector8762 That is a great idea! I wil be looking at this in more depth. It seems to be the perfect solution.

Hope it works out for you!

I been researching PASH, AGS, thremomass, homes for the last 3 years now. I intend to build a earth home In Vilas Co. Wis. I built 3 ICF house's and 1 ICF addition. I been a carpenter for 32 years and 1/2 of that time is concrete forming. I think from all that I read about solar/thermo mass/heat valts, and how much storage I will need to keep a 1500 sq ft' earth home at 70 deg. MY best bet to get it right the first time is to build the earth home with ICF's, 4' frost walls, BUT turn thatfrost wall area into a cistern for water storage. I could build a 6 inch slab suspending the water. If I want it warmer in the place just add more water to the cistern so the water level reaches the bottom of the concrete slab. OR even build cones pointing downward in the water, and if/when I want it warmer. Just add more water so the concrete cone mass is under more water for more contact. Of course the whole cistern walls will be coated as well as the bottom of the slab/cones, so water wont wick up into the slab. Has anyone read anything like this? The ICF's will be 1/2 the insulation and maybe add 2 more inches plus 2" to 4" insulation on the slab floor of the cistern. I have 6, 3' X 6' solar panels for heating the water. Set up a pex closed loop in the water to the solar panels. And retire with no heating bills........Has anyone come across any informatiom close to what I would like to do???????...............2r3d

Sounds like a very adaptable system, I went with insulated knee walls, insulated rock mass and concrete block ducting served by inlets through slab from living area with central collection and return or venting to control heat gain. icf provided the thermal mass and structural strength in this tornado prone area. Window shade angles help control solar input passively . I bought a south slope piece of property that has made this much easier. If my calculations are correct the house design will give aprox 50% of winter heat required and 25% of summer cooling required. my walls are thermaly tied to the slab and floor can be covered with any material of choice. But if I am wrong despite my models and calculations I would be hard put to effect change now.

I like the cistern idea but I think you need it to be thermally broken from the living space or you will  have possible overheating in the summer.

We are considering the same setup but would  have the cistern  as a heat sink and take heat out to flow through radiant floors in the winter evenings ( or cloudy days).

What are you going to use to waterproof? Have you any ideas on what it will cost to do this yet?

I seen a water saving segment on PBS I think it was. Anyway it stated that any water 100% void of sunlight will grow nothing and become sterilized. It showed a above ground black metal tank that caught rain water. They used that water for drinking. So that has me thinking about not having to worry about foul smelling water. As far as the leaking that could occur, I used water stop on construction jobs where we built concrete tanks. So If I installed water stop between the footing and the foundation walls, calk all corners before I add a second 2 inchs of foam, calk all corners again, thin coat that second insulation, then add the same kind of rubber roofing they use for flat roofs, glue all joints. I feel leaks wont be any trouble. But I will need to know that the rubber roofing material will last if it's in super warm water 100% of the time? It's mighty tempting to think about water over clay as the heat storage medium since it can hold so much more heat. Just typing all that work needed to stop the water has me re-thinking again. For me to build it with my own labor, it shouldnt cost but 2 to 3 grand more. 28 sheet of 2" foam $560, the 4" but now 6" slab, so that goes up 50% $1,340 more, Concrete block to act as a ledge for the floor to sit on would be seconds so mabe 300 bucks????. Thin coat material is cheap, But that rubber roofing????? I know a place where I can buy take off pieces. But who wants to deal with re-work materilas that might have 1/2 of its usefull time already spent? I'm not attached to this idea, its just outloud thinking. Anybody out there know of anyone who has built a A.G.S or a P.A.H.S house in Wisconsin? From what I read it sounds like the way to go, but it's going to be tough to pour a concrete floor over the ground without insulation below it, let alone all that concrete wall surface....... Thanks for the input.......

I gave you every bit of good advice a seasoned engineer could 2r3d, but you reject it all out-of-hand. So I don't understand why you asked?

Quantum, I'm just soaking up Information here. I did indeed take in what you stated, It now has me thinking. If that 1,500 sq. ft. X 4' high area will be way to much to heat and a 1,500 gal. tank could do the job. I could build that 1,500 gal tank within the frost wall area of the house. Save on insulation, save on suspending all that concrete floor. I just went back to see what else you wrote, can't find that post. did you delete it? Can someone delete a post once it's up? Quantum How much faith do you have for the PAHS or AGS working here in Wisconsin?....

Wondering if your TF Systems ICF house has been built  yet.  We are talking to them about doing the same thing for both below and above grade walls; 5" of foam on outside with 3/4"mag board as form/interior wall surface.  We will provide the mag (dragon board), the Salt Lake City TF plant will imbed the ties in the 5" of foam, so exterior will be ready for stucco lath, cedar shingles, cultured stone, etc.  It will cost extra to have the ties imbedded, but we want the thermal mass.  Cold nights, sunny days in Park City, Utah area.