Thermal insulation

The thermal insulation properties of a material and product are characterised by two values – the thermal conductivity coefficient λ [W/m-K] and the thermal transfer coefficient U [W/m2-K]. Thermal insulation properties depend on the density, porosity, humidity and raw material composition of autoclaved aerated concrete. As with other porous materials, the thermal conductivity coefficient λ of this material increases with increasing density. The higher density means that the air pore content in the material has decreased, while the volume proportion of the frame, which has a significantly higher λ value than the air, has increased. The thermal conductivity coefficient also increases as a result of moisture in the material.

Values of thermal transfer coefficient U [W/m2K] for individual classes of density and wall thickness

Gross density [kg/m3]

Declared thermal conductivity coefficient λ 10dry [W/m-K]

Calculated thermal conductivity coefficient λ [W/m-K]

Value of thermal transfer coefficient for walls made of SOLBET blocks with specified gross density and thickness expressed in mm U[W/m2-K]

60

80

100

120

180

240

300

360

420

400

0,11

0,12

     

0,46

0,37

0,32

0,27

500

0,13

0,14

   

0,97

0,69

0,53

0,43

0,36

 

600

0,16

0,17

1,91

1,56

1,32

1,14

0,81

0,63

0,52

0,44

0,38

700

0,18

0,19

   

1,25

 

0,70

   

 

NOTE:

Thermal insulation parameters are provided in declarations of performance. These are thermal conductivity coefficients declared λ 10, dry (i.e. for the material in a dry state). Calculated thermal conductivity coefficients, taking into account the stabilised moisture content, should be used for the calculation of the thermal transmittance. This coefficient is given in the table above in the third column (calculation of thermal conductivity coefficient).