GEOTHERMAL HEAT/AC

[indyjps]

Im building a commercial buidling in stages
the first build this summer will be a 30 X 44 shop 12 ft walls for me, Im going to run pex tube in the concrete so I can set up a system later.
the second build, 1-2 years will be 40 x 64 and will just be storage units for rent, considering putting a paint booth in this side for my own use and theres a few free lance painters in the area Ive known for years that will rent it out.

Ive been reading up on geo thermal, whats your experience with insulating under the concrete slab, this is the stage Im at, running utilities in the next 2 weeks and getting some concrete in by mid june. Im using all side job labor (friends of friends) and my own labor so the time frame moves around.