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.
Reduce electric bill by installing radiant barrier in attic?
- Thread starter soupcxan
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Free To Canoe
Thinks s/he gets paid by the post
Interesting thread. Need to insulate my cottage. Primarily want to reduce the humidity inside of the old block building.
Free to canoe
Free to canoe
It is a cement block structure? Some folks pour perlite or other insulation into the block cores, but this really isn't worth the time and trouble, since the heat transfer through the block webs is so much more significant than the heat transfer across the voids in the block. Sheet foam insulation either inside or outside of the walls is the best way to go--it works very well. It's usually cheaper and easier to put it on the inside, though it's a tiny bit less effective (because the thermal mass is outside the insulation).
