I have a client in a 2-pad ice rink / arena, one side has 16″ of fiberglass insulation with foil facing the ice surface installed and hung about 8′ from the underside of the roof deck. The other side has less space, the same insulation but it is bound tightly to the beams on the perimeter due to lower roof heights. My questions are the aluminum foil faced insulation a low-e material? Would the rink benefit from attic heat gain if a double bubble with dual foil face were to be installed below the existing insulation or would it be best to be installed in the attic?
Yes, the foil faced fiberglass would qualify as a low-e surface.
As to your second question, if I understand the structure you described, installing a radiant barrier or reflective insulation in the attic would provide a thermal benefit to the system. I don’t envision any value of installing one below the fiberglass with the aluminum facer. If you can install on the underside of the roof in the attic area, that would be best.