λD and λdesign


The technical datasheet of STYROFOAM™ products shows more than just one λ-value, what might raise the question which λ-value to choose for the U-value calculation - λ (lambda measured), λD (lambda declared) or λdesign (lambdadesign)?

For the building industry only two lambda values are of interest: λD and λdesign.

λD according to EN13164 is used in all EU countries except Germany to calculate the U-value of an element. λD represents 90% of the production with a confidence level of 90% considering the rounding according to EN 13164.

The λdesign value according to DIN 4108-1 is dedicated to Germany and must only be used in Germany to calculate the U-value of an element.

λdesign values of STYROFOAM products can be obtained upon request.

Aluminium Faced Sandwich Panel 

Figure 06: Aluminum-faced sandwich panel

 

The following chart gives an overview about the lambda values for different STYROFOAM™ products:

Product λD
STYROFOAM™ IBF-X 0,033
STYROFOAM™ IBF-A 0,033 (<80mm)
0,034 (80-120mm)
0,036 (>120mm)
STYROFOAM™ LB-X 0,029 (≤70mm)
0,030 (71-120mm)
0,031 (>120mm)
STYROFOAM™ LB-A 0,033 (<80mm)
0,034 (80-120mm)
0,036 (>120mm)
STYROFOAM™ RTM-X 0,029
STYROFOAM™ RTM-A 0,034 (≤70 mm)
0,035 (>70 mm)

Table 2