Radiant Barrier:Dust & Conductive xfer
I'd like to ask two very specific questions regarding Dust & Conductive Heat Transfer.
Consider an RB Product: Made into a triple-layer material, each layer is a double-sided aluminum reflective surface with emissivity of .03, each layer is air separated by a "scrim" of very low-conductive material. Therefore, there are 6 reflective sides making up 3 layers separated by 2 scrims. The scrims force & maintain an air gap between each layer: thus the middle layer has very little surface area touching neither the hot nor cold side and stays dust-free.
Question) Even if the top becomes dusty and the top layer reflectivity is reduced significantly, doesn't the RB still work "nearly as well" as when dust-free to reduce heat gain/transfer through the barrier?
Question 2) Would not the emissivity remain .03, even when laid against a surface such as insulation (as an example of on the floor of an attic)?