Thermal conductivity coefficient (λ) is a fixed value specific to each subsance. It is the measure of the ability of a material to allow the flow of heat from its warmer surface through the material to its colder surface, determined as the heat energy transferred per unit of time and per unit of surface area divided by the temperature gradient, which is the temperature difference divided by the distance between two surfaces e.g. the thickness of the material, expressed in watts per Kelvin per meter. 

See the table below presenting thermal conductivity coefficients in different building materials. Low thermal conductivity means high insulation values. Mekpan Panel guarantees ideal insulation in its sandwich panels with small polyurethane filling thickness.

Considering their multipurpose use and long durability polyurethane foams are the best choice for insulation.



  Polyurethane XPS Rock Wool EPS Glass Wool Concrete
Thermal Conductivity Coefficient (λ)(W/mK) 0,022 0,028 0,033 0,035 0,040 1,7



U-value, or thermal transmittance is the rate of transfer of heat through a structure (which can be a single material or a composite), divided by the difference in temperature across that structure. The units of measurement are W/m²K. When determining sandwich panels’ filling material thickness thermal transmittance must be taken into consideration. 


Panel Thickness Thermal Transmittance or U-Value (W/m²K) Thermal Transmittance or U-Value (Kcal/m²h C°)
40 mm 0,4973 0,4276
50 mm 0,4056 0,3488
60 mm  0,3424 0,2944
80 mm 0,2611 0,2245
100 mm 0,2110 0,1814
120 mm 0,1771 0,1522
150 mm 0,1426 0,1226