Make a plan for old building insulation - How to proceed?

As already written, strange that a different font and different indentation are used for the thermal transmittance coefficient... Someone must have thought that the value is so absurd and devoid of any reality that they have to highlight it with a different font style. The product does not explain how something like this is supposed to be possible... but instead of explaining it, just says try it yourself...

Please carry out the experiment as described above.

It is stated in many places on the internet how it works.

How a theoretically unattainable value is practically achieved is nowhere explained. Not on the internet and nowhere else.

No totally simple experimental data? Why not?

Fill two identical thermos flasks with identical amounts of boiling water. The only difference: one is coated. Measure water temperature at times t1 - t10. Create a chart and upload it here. Easy to do, where's the problem?