phenolic foam · 250mm
R 12.5
U 0.079 W/m²·K
phenolic foam, 250 mm — R 12.5
250 mm divided by a conductivity of 0.02 gives an R-value of 12.5. The U-value is 0.079, so a square metre leaks 1.58 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
- 250 mm
- Thermal conductivity
- 0.02 W/m·K
- Thermal resistance
- 12.5 m²·K/W
- U-value
- 0.079 W/m²·K
- Heat lost per square metre
- 1.58 W
- As concrete
- 20 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 panel88 mm
- rigid polyurethane288 mm
- extruded polystyrene350 mm
- graphite EPS388 mm
- white EPS450 mm
- glass wool462 mm
- mineral wool500 mm
- cellulose525 mm
- timber1625 mm
- plasterboard2250 mm
- concrete20000 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 250 mm of phenolic foam?
12.5 — 250 mm in metres divided by a conductivity of 0.02.
Q. And the U-value?
0.079. That is 12.67 — the resistance plus 0.17 of surface — turned upside down, and a square metre leaks 1.58 W across 20 degrees.
Q. How much concrete would match it?
20 metres.
Q. Which standards does it meet?
At 0.079 it clears 3 of them.