R-Value indicates resistance to heat loss, and measures a mass insulation’s ability to slow down heat flow through it. R-Values tell how well a product absorbs and holds heat energy, not how well it redirects it. rFOIL works by reflecting heat energy back in the direction of its source, and rFOILs true performance is not measured by the R-Value. Just as the absorbency of a raincoat is unrelated to its ability to repel water, the R-Value of rFOIL does not fully measure its ability to insulate and redirect heat energy.
The ASTM C236-1224 tests that determine a products R-Value yield the following results for rFOIL Reflective Insulation:
Heat Flow Down = R-10.6
Heat Flow Horizontal = R-6.8
Heat Flow Up = R-5.3
NOTE: All materials have three separate R-Values, as above, depending on the direction of the primary heat source. Most insulation manufacturers do not provide all three values when labelling their products.