Extreme Insulation
Aerogel insulates better than still air because a molecule in a 20 nanometre pore never gets far enough to hand its energy on.
— W/m·K
Composite conductivity including the radiative term
Setting aerogel and fibre fractions above 100% between them drives the air fraction negative and the result stops meaning anything — the model does not police it, so check the two add up sensibly. The structure factor is fitted, not measured: it hides all the morphology the two-bound blend cannot represent, and it must be recovered from guarded hot-plate data on the actual composite. Compression matters more than any of this — an aerogel batt at half thickness under a pack strap is a different insulator, and the model assumes the quoted thickness holds in use.
Aerogel-Infused Fabric Thermal Conductivity Modeler — free, with the formula and a worked example, at Textile School.