On Jul 27, 10:20*am, "Existential Angst" wrote:
It would seem that if air itself was so good, solid insulation wouldn't be
so high a priority

Neither fiberglass nor Styrofoam are "solid". They are basically air
with a tiny bit of structure to keep that air from moving (much)...

Even if your attic were hermetically sealed, the air in it would be
moving all over the place (though too slowly to notice).