I regularly contribute to the geo forum but am new here. It just occured to me that this was a more appropriate forum for my (heatin' horses) thread over there.
I was contacted by a GBT spectator near my area (mid Mich.) who is building a (loosely) 5600 SF barn for his business of breeding/training/selling horses.
Warm air is not preferred (don't want to blow anything in a dusty barn), so radiant is attractive yet complicated by dirt floor stalls with rubber mats and only a main aisle of concrete.
Desired temp is average of 50 or so degrees and always above freezing.
Water to water geo sometimes <120 degrees is the proposed source of heat. Interested in ideas of delivery.
Thanks for your help,
Joe

Hydronic radiant floor heating of course.

the main aisle *might* be enough, depending on how well insulated your shell is (and if you're going to heat, you definitely want to insulate) and how big it is.

If not, some addition of radiant walls or ceilings might help out enough.

I think if you just ran radiant underground from everything about 10 feet in from the edge you would have enough radiant to keep it warm. Sure some covered parts might not radiate as well, but who know maybe if it is warmer the animals might prefer lying on the ground?

I don't think that radiant in the center only will work because the heat load is from the perimeter. radiant in the outside walls will be too inefficient. the only options are the ceiling or floor.
What is the ceiling of the barn like?
In general, for animal shelters a heated floor is recommended. This is usually implemented in a slab, but I understand that a dirt floor is probably required for the hoofs. Running the tubes unprotected in dirt isn't a good idea so they would have to stay in a slab. What if the stall slab was dropped 9 inches from the center aisle and the stalls were filled with dirt? is 9 inches of dirt enough?

this isn't a comfort application Bill. You can keep a shell heated enough without being in the perimeter, especially if it's an open area.

I don't mind running tube unprotected in dirt (big fear of unprotected tube is difficult repair in 'crete which is a non issue here), however, the rubber mats I mentioned on stall floors will impede radiation.
While comfort is not the thrust here, This is an are that has seen a week of -20 in the last 20 years, so delta T has to be at least 53 so that Mr. Ed wont have to chew his water.
I appreciate everyone's advice, keep it coming.
J

rubber's not a big deal from a heat transfer standpoint.

Tubing unprotected in dirt, however, very well could be a big deal. for instance I have no idea what animal urine will do to PEX, but I can easily imagine it is not good, and most tubing is not really supposed to be immersed in wetness long term or the layers can de-laminate.

I am still not convinced that the center walkway can't do the job. In an insulated shell it is not hard to stay above freezing; in fact, the ground itself (if insulated from the cold outside vertically down below the frost line) can become a heat emitter in that case... as you drop below dirt temperature it will give up heat to the space. Whatever heat the walkway can dump will only improve the situation.

What if you laid your Pex in concrete slabs and stood them vertically between the stalls. May only need a slab in every other partition. I would have wood on either side so horses don't hurt themselves. Or maybe that is n't necessary.