# Variables

<figure><img src="/files/a281ef8f09e746b9feb09e0dc714eec94d60559e" alt=""><figcaption></figcaption></figure>

In all fields with a calculator icon at the right end, one can access the variables and even enter complete formulas. The possibilities of the formulas will not be discussed further here; these can be studied in detail in the supplied documents for the variables and combined elements. What is important here, however, is that one can access both system variables and user variables.

* The system variables are a fixed set of variables provided by the program and cannot be modified or extended by the user.
* User variables are variables that can be created by the user. In the HRB editor one can, via 1.2., *Variables* create any number of custom variables.

<figure><img src="/files/5630ed1cf4fbb152a9cb5563c9c6be56a8b0b682" alt=""><figcaption></figcaption></figure>

The creation of variables will not be discussed further here; as already mentioned, this can be read in detail in the document 'Variablen\_Udxx\_xxxx.doc'. One aspect is particularly interesting in connection with HRB. In the image above you can see that the switch 'E' is set for the variables. This means that the value of the variable should be taken from external sources when this variable also exists outside (externally) of the HRB module. What does "outside the HRB module" mean here?

Variables exist in the HRB module but also in the building model. From the perspective of the HRB module, the building model is external (outside). Thus, if a variable in the HRB module has the 'E' switch active and the same variable (same variable name, e.g. V\_WB\_PfoB) also exists in the building model, the value is not taken from the HRB pre-run file but from the building model. Only if the variable does not exist there will the value be taken from the HRB pre-run file.

This allows one to change the dimensions and the position of all components without starting the HRB editor. One only needs to change the value of the corresponding variables in the building model. For this, the variables must be created in the building model as well, which can be easily accomplished via the variable storage capabilities.


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