Low-e coatings screen infrared heat from moving through the glass, either inward, outward, or both
Too much of a good thing can kill you. Including sunny weather.
If you can't build to stay dry, build to tolerate wet
Old Building Details That Work
Thin foil can block massive amounts of heat transfer, but it needs a massive temperature difference to be effective. So, insulation sort of makes radiant barriers irrelevant.