Thermal insulation by Koolfoam

Koolfoam is an exceptionally good insulation material. This is the result of its extremely low density and closed cell structure. It consists of airfilled polyhedral cells, 0.2 - 0.5 mm across, with polystyrene walls about 0.001mm thick. The polystyrene walls occupy only about 2% of the total volume: the rest is air which is trapped in the cells and cannot pass from one cell to another. Still air is an extremely poor conductor, so that little heat can move from one cell to another and the alternative paths along the thin polystyrene cell walls are equally unsuitable for rapid heat transfer.

The thermal conductivity of cellular materials made from Koolfoam varies with density, and with temperature. Within the normal density range of material used in building the variation of conductivity with density is comparatively small.

At 10°C the thermal conductivity of expanded Koolfoam of density 20kg/m is 31-36 mW/m.k. However, in carrying out insulation calculations for heated buildings it is usual to use the same nominal value for all densities and temperatures, eg the value of 30 mW.m.K.

The thermal conductivity of expanded Koolfoam does not vary with time, unlike cellular materials whose cells are filled initially with gases other than air.