Program and model documentation

THERAKLES uses a numerical solution method with the following special features:

  • implicit time integration while maintaining the required accuracy of 5 significant digits
  • variable integration time steps, which are adjusted based on an integration error estimator
  • detailed calculation of the temperature and humidity profiles in the wall/floor/ceiling constructions using the finite volume method
  • innovative solution method for the modified Newton method taking into account the sparse matrix structures

By using this modern and efficient calculation algorithm it is possible to solve detailed physical models with high accuracy very efficiently.

THERAKLES is a non-geometric model. It is therefore possible to enter a base area and, by entering a height, a volume independently of the entered wall/floor/ceiling areas. It is therefore not specified whether the model works with external or internal dimension reference.

Functional overview

Thermal model++
Hygrothermal model++
Optimized numeric calculation core++
Material database++
Window and shading database++
Climate database++
Modelica Export++
FMI Export (ModelExchange and CoSimulation)++
Bug fixes and feature improvements since June 2017+
DIN 4108-2 mode+
Project report+
Comparison Standard Version with Pro Version

project file format

The project file is in XML format using UTF8-encoded character strings. The individual entries are self-explanatory and correspond to the respective entries (and units) in the program interface. In addition to the project input data, all database entries used are also included in the project file. In this way, project files with their own definitions can be transferred from one computer to another without exchanging the databases themselves.

When reading a project file into THERAKLES, all definitions (materials, constructions, etc.) that do not yet exist are transferred to the user-defined databases of the THERAKLES installation. Database elements are linked via IDs. If, for example, a new material is created in each of two THERAKLES installations, this material will have the same ID in each of the independent program installations. If you now copy a project from one program installation to the next, there is an ID collision. This is resolved by the imported material receiving a new, unused ID and being entered into the user database. In the project file, the respective ID is replaced in all references. This means that the project file on the second installation is no longer identical to the original project file. Dimensioning according to DIN 4108-2

DIN 4108-2 describes two methods for verifying the minimum requirements for heat protection in summer. For one of them, the proof is provided with the help of the thermal building or room climate simulation. THERAKLES can provide this proof. The requirements and boundary conditions for this can be found in Chapter 8.4 of the standard. For a standard-compliant verification, the calculation mode in THERAKLES must be set accordingly. When selecting the ‘DIN 4108-2’ mode, the selection is restricted in such a way that only the boundary conditions and model parameters described in the standard are permitted. To do this, some tabs of the model options are deactivated. This is necessary because, according to DIN 4108-2 Chapter 8.4.1, such proof is only valid if the normative requirements and conditions are strictly adhered to. The geometry and room data, project information and settings for shading can still be edited. In the advanced settings, the option of calculating moisture is deactivated because this is not part of the standard. An evaluation of the results, with a description of the fulfillment of the requirements of the standard, can be viewed in the report.

File format for time series

In THERAKLES, time-series files are used to enter time-varying temperatures in neighboring zones. Either the CCD format or the TSV format is used.

CCD format description

# Zeilen mit # sind Kommentarzeilen.
# Schlüsselwort Temperature zeigt Temperatur an
# Zwischen Temperature C Zeile und Daten muss eine Leerzeile sein
# Der Zeitpunkt 0 d 00:00:00  und 365 d 00:00:00 sind identisch und
# dürfen nicht zweimal vorhanden sein.

Temperature  C

0   00:00:00    3.02
0   01:00:00    3.02
0   02:00:00    3.02
0   03:00:00    3.02
0   04:00:00    3.02
0   05:00:00    3.02
0   06:00:00    3.02


364 19:00:00    11.61
364 20:00:00    11.61
364 21:00:00    11.6
364 22:00:00    11.59
364 23:00:00    11.58

The line with the type definition and the unit is important:Temperature C , followed by the actual data. The numbers are separated by spaces or tabs. Each line defines a point in time and in the last column the temperature value (English number format, do not use a comma! ).

The points in time must be strictly increasing, whereby the time intervals can be arbitrary (variable time steps are possible). Since THERAKLES carries out annual simulations, the times are0 00:00:00 and365 00:00:00 are the same and accordingly both (with possibly different temperatures) must not be present in the file. The CCD-FILE-TEMPLATE.ods file can be used to conveniently create CCD files (LibreOffice, Excel, etc.). The best way to create the actual CCD file is in a text editor, into which you can copy and paste the entire previously marked content of the CCD file template.

result report

The results report allows the creation of a print-ready summary of input data and results. It is primarily designed to display the results of a DIN 4108-2-compliant design. The creation of a report is started by clicking on the associated button in the main window. A report can only be created meaningfully if a calculation has been carried out beforehand. Therefore, after clicking on the button, the query window shown below appears first. The report view is divided into 3 sections. In the view area you can see the current version of the report, just as it would be printed. What is displayed can be adjusted in the settings area. The button area allows printing or exporting. The report is divided into the sections described below

Online manual

For more information, see the online help

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