Leitwert Lambda Equivalent Calculator (LambdaEQ Tool)
Objective:
The Lambda Equivalent Calculator (LambdaEQ tool) is used to calculate the thermal conductivity of a component consisting of a building material with a simplified replacement model of thermal separation (equivalent Lambda of the simplified model), in such a way that the thermal conductance of the simplified model must be equal to the conductance of the detail model.
If necessary, the detail model is available as a 3D construction, the simplified model as 2D only. In such a case L3D/dZ = L2D must be used.
By variation of the building material property, the lambdaeq of a building material is to be calculated iteratively for an inputable or calculated thermal coupling coefficient (target value) in the tworoom case.

Detail model ("Isokorb" K50CV35h200) 

Equivalent model (Insulating block) 



==> 




==> 



L^{3D} _{detail} 
= 
L^{3D} _{simple }( λ_{eq} ) 

The target conductivity value can be set as follows:
 Calculation from the current project (ProjectDetailName empty)
 Calculation from the specified project ProjectDetailName
 Numeric input (ProjectDetailName empty)
The thermal conductivity SimplifiedLambda of a building material SimplifiedMaterialNameToVaryLambda of a simplified model is to be calculated.
The resulting conductance SimplifiedLeitwert of the simplified model shall differ only slightly from the target conductance. The specification is made with the relative deviation SimplifiedConductanceIterationMaxRelativeDelta related to the magnitude of the conductance.
The simplified model can be specified as follows:
 Construction from the current project (ProjectDetailName empty, ProjectSimplifiedName empty) in which elements from the DetailGroupToRemove group are removed (the elements SimplifiedMaterialNameToVaryLambda are retained, however)
 Construction from the specified project ProjectSimplifiedName in which elements are removed from the DetailGroupToRemove group (the SimplifiedMaterialNameToVaryLambda elements are retained)
The iterative process ends when:
 The desired accuracy (precision) SimplifiedLeitwertIterationMaxRelativeDelta is reached (success)
 The specified maximum number of iterations SimplifiedLeitwertIterationsMaxCount is reached (no result)
When calling the LambdaEQ tool from the menu, the current project must first be saved.
When exiting the tool, the project is restored (read in from the file). The settings and results made in the tool are automatically saved in the project (automatic saving again).
Reset 
Resetting the control parameters to their default values 
Undo 
Resetting the control parameters to the values when the dialog is opened 
Cancel 
Abort the function 
Start 
Starting the calculation 
Done/Save 
Save settings and results in the current project 
The Settings
Target Data: 
ProjectDetailName 
(optional) Name of the project of the detail model for the calculation of the Conductivity DetailLeitwert.
If empty, then the project currently being processed is used.
Default: empty 
DetailLeitwert 
(optional) The thermal coupling coefficient of a detail model (and the target variable which is to be approximated by the conductance SimplifiedLeitwert of the simplified model
If empty or 0, it is used for the detail model (ProjectDetailName or current project).
If not empty, it is calculated with the conductance of the detail model
(ProjectDetailName or current project).
Default: 0 
ProjectSimplifiedName 
(optional) Name of the project of the comparison model (simplified
model) for which the variation of the thermal conductivity
SimplifiedLambda of a building material
SimplifiedMaterialNameToVaryLambda results in one (approximately) identical thermal conductance SimplifiedLeitwert like the DetailLeitwert.
If empty, the simplified model is created by removing the
elements belonging to the group DetailGroupToRemove (but the elements SimplifiedMaterialNameToVaryLambda are not
maintained)
Default: empty 
DetailGroupToRemove 
(optional) The elements belonging to the group DetailGroupToRemove are to be removed from the simplified model (the
Elements SimplifiedMaterialNameToVaryLambda are however maintained)
Default: empty 
SimplifiedMaterialNameToVaryLambda 
(Mandatory field) Name of the building material from which the value of the Thermal conductivity SimplifiedLambda is to be adjusted (varied) until the thermal conductance SimplifiedConductance of the simplified model matches the conductance DetailLeitwert of the detail model except for a relative deviation SimplifiedLeitwertIterationMaxRelativeDelta.
Default: empty 
Results Data: 
SimplifiedLambda 
(optional) The thermal conductivity of the building material
SimplifiedMaterialNameToVaryLambda of the simplified model is assigned. In the course of the calculation, the value of the
thermal conductivity SimplifiedLambda is adapted (varies) until the thermal conductance SimplifiedLeitwert of the simplified model matches the conductance DetailLeitwert of the detail model except for a relative deviation SimplifiedLeitwertIterationMaxRelativeDelta.
If empty or 0 it is calculated.
If not empty, it is inserted and checks whether it matches the desired
accuracy criteria, and if not, recalculated. 0 as result: the calculation failed.

SimplifiedLeitwert 
The thermal conductance of the simplified model ...
0 as result: the calculation failed.

SimplifiedLeitwertAbsoluteDelta 
Amount of the difference between thermal conductance DetailLeitwert of the detail model and the SimplifiedLeitwert of the simplified model.
0 as result: the calculation failed. 
SimplifiedLeitwertRelativeDelta 
Conductance deviation related to the amount of thermal conductance DetailLeitwert.
In the course of the calculation this is compared with the accuracy criterion SimplifiedLeitwertIterationMaxRelativeDelta.
0 as result: the calculation failed. 
Auxiliary Data: 
SimplifiedLambdaRangeMin 
In the course of the calculation, the value of the thermal conductivity
SimplifiedLambda varies in the interval SimplifiedLambdaRangeMin to SimplifiedLambdaRangeMax.
Default: 0.001 W/mK
Should be < SimplifiedLambdaRangeMax

SimplifiedLambdaRangeMax 
In the course of the calculation, the value of the thermal conductivity
SimplifiedLambda varies in the interval SimplifiedLambdaRangeMin to
SimplifiedLambdaRangeMax.
Default: 1000 W/mK
Should be > SimplifiedLambdaRangeMin 
SimplifiedLeitwertIterationsMaxCount 
The maximum number of iteration steps SimplifiedLeitwertIterationsCount in the course of the SimplifiedLambda search.
Default: 50 
SimplifiedLeitwertIterationsCount 
The current number of iteration steps SimplifiedLeitwertIterationsCount in the course of the SimplifiedLambda search. 
SimplifiedLeitwertIterationMaxRelativeDelta 
The accuracy criterion and termination condition. The search for SimplifiedLambda is considered successful if the relative difference between the conductance DetailLeitwert of the detail model and the SimplifiedLeitwert of the simplified model (which is calculated from the thermal conductivity SimplifiedLambda) is below this limit. Default: 0.0001 (also corresponds to ISO 10211) 
