however, the thermal resistance of glass wool is fairly well known.
The ISOVER range presents 3 main families of mineral wools, differentiated by their thermal resistance at equal thickness: λ = 0,032; 0,035 or 0,040, or R = 3,1; R = 2,85 and R = 2,5 in 100 mm thickness, as well as the Multimax R = 3 range in 90 mm.
Source Isover
Thermal resistance = thickness / lambda / surface
Watch out for the units as usual.
The reflective coefficient of a metal also, the radiative emission according to the temperature (tables of data exist in infrared thermography, to see the last page of my doc) etc ...
after that it's just a matter of calculation.