
So here starting on the same principle of isolating with emprisoné air based on this diagram:

If I read between 30 and 40 mm of a vertical air space, it has a thermal conductivity of 5.5 / 5.6, 5.6 take which gives a global R 0.18 ... not great!
But if we suppress radiation (movie reflector) and that limits the convection well hey you fall for about 1 30 40 in mm (well, we find the equivalent R Styrodur type extruded PES 40 mm c ... is not a coincidence!)
So here is the idea: to double the walls with an air space of 30 to 40 mm (more or less waterproof but more waterproof is better) and this thanks to a simple "cladding" (the more compartments the better. 'is thermally) and a thermoreflective film simply attached to the cladding.
Here is the schematic diagram:

The "aluminum" face will obviously be against the wall. The heated room being on the right in the diagram. And this technique would only work with "interior" walls between a heated room and an unheated one.
Character I really want to test (I have all the gear) unless there are indications against?
At the price levels: a film to 3 5 mm PE with aluminum costs between 1.5 and 2 € / m² lathing is proces of nine pallets, say 1 € / m²?
It remains econological ... if it works thermally course!
Edit: read this technical study https://www.econologie.com/etude-techni ... ts-minces/ for theory and practical tests on thin insulators.
These are only "effective" with one or 2 air knives!