The main reason to use any insulation is to slow the heat transfer from the interior to the exterior or vice versa. So, let’s look at the r-value of bubble insulation. You can expect an R-value of 1-2 for single-layer bubble wrap insulation. Double bubble wrap insulation can have higher R-values, and some claim as high as R-8.
The lines get blurry when manufacturers compare building assembly R-values and product R-values. When foam insulation R-value is rated, it is the material itself. So an r-10 foam board means that one building component has an R-10 value. Minus if it degrades over time like XPS foam insulation.
Nowadays, the bulk of the remaining confusion over foil-faced bubble wrap is about the insulation of ducts. Since construction codes are becoming stricter, many states now require ducts to include R-8 insulation.
Instead of promoting the bubble wraps to concrete builders, many producers are marketing it to HVAC contractors to install duct insulation quickly. Online advertisements for “R8 bubble wrap duct insulation” lure unwary contractors into marketers’ traps.