The attic is 65m².
I am thinking of using "SteicoFlex" panels which have the following characteristics:
Lambda: 0.038 W / (m * K)
Density: 50kg / m³
"Phase shift": 2100 J / (kg * K)
Solution A: thickness 14cm
R would be 3.68 (= 0.14 / 0.38)
Solution B: thickness 20cm
R would be 5.26 (= 0.20 / 0.38)
Questions:
- The larger R, the better. But what exactly does R mean?
What is its unit of measure?
What is the difference between the two results?
Can someone calculate the phase shift for the two thicknesses? (and explain the calculation)?
Is it economically profitable to install 20cm instead of 14? (knowing that the additional cost would be +/- 7 € / m²)
thank you in advance for your help