Why are some insulation materials thicker than others?
An insulation material is characterised by an inherent physical quality, thermal conductivity (or λ-value). The lower this value, the better the material insulates thermally. The ‘thermal resistance’ of a material is dependant upon both its thickness and its thermal conductivity. Therefore insulation materials with a higher λ-value will need to be of a greater thickness if the same thermal resistance is to be achieved as an insulation layer with a low thermal conductivity.
