Each insulating material has a specific thermal conductivity value which represents the ability of a material to transfer heat. Typical insulation thermal conductivity values (in W/mK) are:

  • Cellulose fibre: 0.04
  • Fibreglass (7 kg/m3): 0.057
  • Fibreglass (12 kg/m3): 0.044
  • Polyethylene foam: 0.040
  • Polyester batt (high density): 0.045
  • Polyester batt (low density): 0.059
  • Loose fill (wool): 0.080
  • Loose fill (Rockwool): 0.040
  • Rockwool: 0.033
  • EPS: 0.039
  • XPS: 0.028
  • Polyurethane: 0.028