Originally Posted by soupcxan
I'm considering tearing the RB down. It just doesn't seem to be working, and I am wondering if it is keeping heat in the attic. It's still +110 in there after the sun goes down.
Another small point--keep in mind the principle behind the RB. It's supposed to reduce the radiative transfer of heat from the underside of the roof deck to the top of your attic insulation. Without the RB, the 120 deg F non-glossy, rough, and maybe dark (e.g. highly emmissive) underside of your roof deck radiates IR energy to the top of your attic insulation and heats it up. With the RB in place, this transfer of heat is reduced because the top of the RB reflects some of the IR energy back to the roof deck and also is not radiating it nearly as efficiently to the top of your attic insulation (because the underside of the RB is shiny and has poor emmissivity.) Over time the top of the RB will get dusty, significantly reducing reflection of heat back to the roof deck, but the poor emmissivity toward your tinsulation will be unafffected. But, all of this to-and-fro with radiative heat is only indirectly related to the actual temp of the air in your attic. The RB might
conceivably even make the attic warmer. That wouldn't mean that you couldn't also be saving energy.