Psi-Value Calculator

The Psi-Value Calculator is used for rapid calculation of the thermal heat bridge "correction" factors Psi (Ψ) resulting from the input of U-values and lengths specific to the building component concerned and its thermal coupling coefficient L2D as calculated within appropriate two dimensional, stationary, thermal heat bridge simulation software. Calculating U-values needed is supported by the U-value Calculator integrated within this Psi-Value calculation tool.

U-ValueThe U-Value specific the the components part concerned (as calculated with a U-Value Calculator, for example). Remark: If specific U-Value is provided by a layered construct entered within a U-Value calculator, the checkmark left to the button "Layered Construct" is marked checked and this field is marked read-only. To override the value manually uncheck the checkmark left to the button "Layered Construct".

LengthThe length to be used for the respective U-Value above

Coupling Coefficient L2DThe thermal coupling coefficient specific to the component under consideration (as calculated with a two dimensional thermal heat bridge simulation software, for example).

U * lThe result of the multiplication of respective values of U and l.

Total U * l The sum of respective U * l multiplications.

Psi-Value (Ψ) The resulting Psi-Value (Ψ).

Up to two U-Value and Length pairs can be entered. The formulas used for this calculation are defined in the EN ISO 10211. Remark: Obtaining coupling coefficient L2D can be accomplished with appropriate two dimensional, stationary, thermal heat bridge simulation software. For example AnTherm provides class A precision method of such calculation.

Calculating U-Values with U-Value Calculator

To calculate respective U-Value with an integrated U-Value Calculator, press the button "Layered Construct", build or load the layered construct within the U-Value Calculator which is shown thereafter and confirm the calculated result by pressing the Ok-button therein.
The calculated U-Value of a layered construct is shown in the U-Value field which is then marked read-only. The checkmark left to the button "Layered Construct" confirms, that the value shown is based on respective layered construct.

The actual data of a layered construct can be changed at any time by pressing the button "Layered Construct" again and editing the data within the U-Value Calculator shown thereafter.

  • Remark: The actual data of a layered construct is retained until the application is exited. To save the data of each respective layered construct use the "Save" function within the U-Value Calculator.
  • Remark: You can drag & drop any layered construct (as it is available from a U-Value Calculator if it is run separately) onto the one of U-Value / Length blocks in this window also.
  • Remark: To override the value manually uncheck the checkmark left to the button "Layered Construct".
  • Remark: If no data of a layered construct has been applied yet, the checkmark left to the button "Layered Construct" is shown greyed.

Entering the Thermal Coupling Coefficient L2D obtained from AnTherm

AnTherm's "Coupling Coefficients Report" provides the matrix of thermal coupling coefficients resulting from stationary simulation of respective modelled construction. As AnTherm displays both, the interior and exterior calculated values for precision validation purposes, you can either use any one of the two or apply the mean value of both for example, provided that precision criteria is satisfied.