Is it efficient to use radiant heat to heat two spaces, both over and under, at once?
I recently built a loft (30' x 10') with a dormer within an existing large room (30' x 20') with vaulted ceilings. The long end of the loft (30') is open to the larger space via a balcony. The loft floor, is now also the ceiling over half of the ground floor of the large space. The other half of the large space still has a vaulted ceiling. The entire space is currently heated with radiant over a slab installed in the ground floor.
I would like to install radiant tubing within the loft floor/ceiling and have the radiant effect work both over (radiating up through the floor into the loft) and under (radiating down from the ceiling toward the space below). Unlike in an underfloor joist installation (in a basement for example) where the heat is isolated from the space below and is directed upward toward the floor above, this entire space is open to itself, and, in effect, the radiated heat will be shared (both up and down) within the entire large space.
Will this be effective, efficient and comfortable? What is the best way to radiate the heat in both directions? Would aluminum heat emission plates help with distributing the heat more efficiently?