Many people, builders and home owners, use this stuff as a VB in Sauna.
I use kraft – backed ( solid) builders foil, and have for 30 years + , with mineral fiber batt insulation in frame cavities / period.
(* I work in Vermont and the northeast- and most of my contact is with clients nationwide who tend to live in the colder winter regions)

I’ve checked ‘max in-service-temp.’  info. for this poly/Mylar/foil product ( 180’F or so), which does not suffice for Sauna, esp. a wood heated room.
* FYI : The Finnish Sauna Society will recommend  Sauna operating temps of 80 to 100 C. ( ~ 176′ to 212’F).

I’m sure there are applications where this bubble /foil sandwich product may be helpful-but…

I design and build Sauna to Finnish spec.’s, and have encountered some on line sources in the U.S.  promoting this plastic bubble material for this application…The Finns don’t use it, so why should others…

Your thoughts on  Mfr.’s warrantee,durability, outgassing? My attempts to get info from them has been less than productive.

Thank you-
And remember : think globally, sweat locally!