You can't beat radiant floor heat. when you back trucks in after a call the snow, water and crap drips off them and dries up on the floor. The trucks asorb the heat coming up from the floor and are always warm, Also If you have a high ceiling the heat does not go to the ceiling as long as you don't move it with ceiling fans. The downfall to Radiant floor heat is POOR construction methods, and improper insulation materials. (1) the sub grade HAS TO BE PROPERLY COMPACTED. (2)It HAS TO BE DEAD ON SMOOTH, no humps or dives if 2" construction grade insulation is used, (it will bridge) BUT I DO NOT recomend styrofoam under floors where "heavy point loads" are involved. (A fully loaded tanker, or town plow truck fully loaded and setting on 2-3 axles, will exert some massive weight to a very small area of floor. You need at least 6" of concrete reinforced with #4 rebar criscrossed 16'" OC and 3/16' mesh set on "chairs" holding the bar and mesh with attached 7/8" radiant tubing in the middle of the crete, not under it. I recomend insulating blankets with vapor barier under these floors, as it is not as prone to colapse under heavy loads. Be sure to insulate the building perimiter to a minimum depth of 2'vertically, and also horizontally just under the external ground surface and be sure to place a thermo barrier up to floor surface grade at all doors. Where you have big overhead doors place radiant tubing much closer in front of them.
Also BE SURE you dig a haunch under, and add extra reinforcement under and around floor drains in floor as this area is always weak, due to the open area.
If and when you want to supplement your heating unit with Solar,/ storage tanks, and posibly a wood gasser boiler you can very easily do it, if you initially plumb in supply and return ports caped off. This is no BS, I was a comercial builder and have worked with and certified as an installer for companies such as Radientec, Sun Max Solar, and ProFab Wood boilers, Baxi, and others.
Loren, the Acg