Quote:
Originally Posted by berniebenz
there is a negative value to using a bat type conductive insulation in this area, inasmuch as any bat material will have a higher conductivity than does still air. Bat type, volume insulation is only useful in preventing natural air convection.
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I believe you're missing the point here. Even though the fiberglass batting does conduct a miniscule amount of heat, it offers a surface for your floor to radiate its heat into. Once the radiated heat is spent on the top surface of the batting, the underlying batting prevents this heat from travelling anywhere. It merely compresses the stratification effect to near the source. At the bottom of the batting, the surface temperature is much closer to ambient, preventing much of the radiant heat from heating the air below.