phenolic foam · 300mm
R 15
U 0.066 W/m²·K
phenolic foam, 300 mm — R 15
300 mm divided by a conductivity of 0.02 gives an R-value of 15. The U-value is 0.066, so a square metre leaks 1.32 W across a 20-degree difference.
Standards it meets
- passive house 0.15
- Korean central-region wall 0.17
- loose standard 0.30
- Material
- phenolic foam
- Thickness
- 300 mm
- Thermal conductivity
- 0.02 W/m·K
- Thermal resistance
- 15 m²·K/W
- U-value
- 0.066 W/m²·K
- Heat lost per square metre
- 1.32 W
- As concrete
- 24 m
Thickness for the same performance
This is the number that shows what insulation is worth. Matching 100 mm of XPS with concrete alone would take 5.7 metres of it. No one builds a wall like that — which is why a concrete building only gets warm once a thin layer of insulation is added.
- vacuum panel105 mm
- rigid polyurethane345 mm
- extruded polystyrene420 mm
- graphite EPS465 mm
- white EPS540 mm
- glass wool555 mm
- mineral wool600 mm
- cellulose630 mm
- timber1950 mm
- plasterboard2700 mm
- concrete24000 mm
Nearby cells
Same material, other thicknesses
Same thickness, other materials
How to read this
- Thermal resistance is the thickness in metres divided by the conductivity. Bigger is better.
- The U-value adds 0.17 of surface resistance and then flips the total. Smaller is better.
- Resistances add across layers, so a whole wall is the sum of its parts.
- Conductivity varies by product; the values here are typical for the material.
Frequently asked questions
Q. What is the R-value of 300 mm of phenolic foam?
15 — 300 mm in metres divided by a conductivity of 0.02.
Q. And the U-value?
0.066. That is 15.17 — the resistance plus 0.17 of surface — turned upside down, and a square metre leaks 1.32 W across 20 degrees.
Q. How much concrete would match it?
24 metres.
Q. Which standards does it meet?
At 0.066 it clears 3 of them.