In-floor radiant heat is amazing, but I'm not so sure that there are any systems that integrate a geothermal heat pump with in-floor radiant. That's usually a fossile fuel option.
Mike, I'm pretty sure water furnace offers a water based system as oppsed to forced air. Someone does, I talked to somebody about it. GTHP is the PERFECT system to couple with IFR due to the low temp of the water produced by the GTHP being in the same neighborhood as the temps needed for IFR. There are no issues with terying to keep the return water temp up as GHTP does not have any flue gas exhaust that could condense water in the chimney and cause premature erosion of the mortar and a boiler's cast iron.
Yes a closed loop system is the best option for a pond but I HAVE seen systems that draw and use directly from ponds and streams. A GTHP is really nothing more than a water source heat pump (WSHP) (as opposed to air source) so any way you get water to it works as long as the temperature of the water is within design specs. There is nothing new about WSHPs the newer part is the method of using the earth as a heat sink.
Yes, if you do IFR you indeed must install ductwork anyways in order to cool the home and all along I have been saying "not cheap"
This is where the hybrid design of only "warming" certain floors but then using a hot water coil in the A/C ductwork shines. The overall cost is reduced as you are not tubing the whole place. Just the concrete basement floor and bathrooms, kithcen and any other tile floor. Still I am doing a house this way right now and the price of the system is in the range of $38,000. If we were to tube the whole place and do A/C the price could easily get to $50,000.
The thing about any hot water heating system is versatility. With the same hot water system you can heat your DHW, your home, your pool, you can have towel warmers in the bathrooms, anti bathroom mirror fogging, melt the snow on the steps sidewalk and driveway. Again NOT CHEAP! But available. You can always add these niceties later too, as long as you have a big enough source of hot water.
Barbara, you are smart. Most people design and even begin to build a house before they give serious consideration to heating and cooling it. The correct way is to decide how you want to condition the home and then design around that. As far as solar panels, the compressor in a GTHP will draw a good bit of power but as long as your solar electrical system is adequate, it is not a problem.