No, only the emissive ability adds on - not the hitpoints. Yes, Emissive Armor I is pretty much useless I guess
Well unless you come up against ONE FIGHTER...
since for some reason an entire fighter group's shots are combined into one for purposes of penetrating emissive armor!
The real benefit of UPC's is the increased productivity - A Jubilant population will produce resources at 120% the rate of an Indifferent population, twice as fast as an Angry population, and INFINITELY faster than a Rioting population