Insulation·white EPS 400mm
white EPS · 400mm
R 11.11
U 0.089 W/m²·K

white EPS, 400 mm — R 11.11

400 mm divided by a conductivity of 0.036 gives an R-value of 11.11. The U-value is 0.089, so a square metre leaks 1.77 W across a 20-degree difference.

Standards it meets

  • passive house 0.15
  • Korean central-region wall 0.17
  • loose standard 0.30
Material
white EPS
Thickness
400 mm
Thermal conductivity
0.036 W/m·K
Thermal resistance
11.11 m²·K/W
U-value
0.089 W/m²·K
Heat lost per square metre
1.77 W
As concrete
17.78 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 panel78 mm
  • phenolic foam222 mm
  • rigid polyurethane256 mm
  • extruded polystyrene311 mm
  • graphite EPS344 mm
  • glass wool411 mm
  • mineral wool444 mm
  • cellulose467 mm
  • timber1444 mm
  • plasterboard2000 mm
  • concrete17778 mm

Nearby cells

white EPS 300mm
R 8.33
graphite EPS 400mm
R 12.9
glass wool 400mm
R 10.81

Same material, other thicknesses

white EPS 10mm
R 0.28
white EPS 20mm
R 0.56
white EPS 30mm
R 0.83
white EPS 50mm
R 1.39
white EPS 70mm
R 1.94
white EPS 100mm
R 2.78
white EPS 120mm
R 3.33
white EPS 150mm
R 4.17
white EPS 200mm
R 5.56
white EPS 250mm
R 6.94
white EPS 300mm
R 8.33
white EPS 400mm
R 11.11

Same thickness, other materials

vacuum panel 400mm
R 57.14
phenolic foam 400mm
R 20
rigid polyurethane 400mm
R 17.39
extruded polystyrene 400mm
R 14.29
graphite EPS 400mm
R 12.9
white EPS 400mm
R 11.11
glass wool 400mm
R 10.81
mineral wool 400mm
R 10
cellulose 400mm
R 9.52
timber 400mm
R 3.08
plasterboard 400mm
R 2.22
concrete 400mm
R 0.25

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 400 mm of white EPS?

11.11 — 400 mm in metres divided by a conductivity of 0.036.

Q. And the U-value?

0.089. That is 11.28 — the resistance plus 0.17 of surface — turned upside down, and a square metre leaks 1.77 W across 20 degrees.

Q. How much concrete would match it?

17.78 metres.

Q. Which standards does it meet?

At 0.089 it clears 3 of them.