Thermal conductivities of various substances (how well they conduct heat)
Units are Watts per meter per °C
SubstanceHeat conductivity
Styrofoam
0.01
Still Air
0.023
Wood
0.08
Dry soil
0.25
Water
0.60
Concrete
0.80
Ordinary glass
0.80
Wet soil
2.1
Ice
2.1
Granite
2.7
Lead
35
Steel
50
Iron
80
Aluminum
205
Copper
385
Silver
427