Performing the Calculation
Start the steady-state network calculation: network settings, define operating points, plus start, progress and cancellation in the calculation dialog
Overview
The steady-state calculation is configured and started via its own dialog. There you define the pressure maintenance, nominal temperature difference and any number of operating points. Each operating point is calculated as a standalone solver run; the results are saved with the project. The underlying calculation model is described in Fundamentals of the Steady-State Calculation.
Access
Steady-State Calculation button in the left-hand toolbar — switches to the steady-state calculation view- there, Start Calculation … opens the Steady-State Calculation dialog
On opening, VICUS Districts checks the active network (fittings, open route ends) and the settings of the energy plants. The project must be saved before the calculation. If simultaneity is enabled and no up-to-date simultaneity results exist yet, their optimization is automatically run beforehand.
Network Settings
| Option | Default | Meaning |
|---|---|---|
| Temperature difference | from the network parameters | Nominal temperature difference between supply and return at the consumers in [K]; determines the mass flux per consumer. |
| Pressure at pressure maintenance | from the network parameters | Static pressure in [bar] that the pressure maintenance holds at the reference node; sets the absolute pressure level in the entire network. |
| Position of the pressure maintenance | first energy plant | Energy plant at which the reference pressure is applied; via Energy plant inlet / Energy plant outlet you select the connection side. |
| Maximum pipe pressure loss | from the network parameters | Maximum permissible pressure loss per meter of pipe length in [Pa/m]; reference value for maximum capacity, utilization and reserve of the pipes. |
| Consider pipe heat losses | disabled | Enables the heat exchange of the pipes with their surroundings according to the assigned boundary condition; if the option is disabled, all pipes are calculated adiabatically. |
Temperature difference and maximum pipe pressure loss are the same network parameters as in the pipe sizing and are pre-filled accordingly.
Detailed Settings
The collapsible section Detailed Settings contains the calculation options:
| Option | Default | Meaning |
|---|---|---|
| Supply type | from the network | Central circulation pump or Decentralized circulation pumps; affects the identification of the worst point. |
| Simulation time | 24 h (1–720 h) | Simulated duration until the steady state is reached. Increase the value if the calculation does not converge. |
Operating Points
Each row of the Operating Points table defines an operating point that is calculated as its own solver run. Use the tool buttons to add or remove operating points (at least one operating point remains). The Name is generated automatically from the settings and can be overwritten.
| Mode | Additional input | Calculated state |
|---|---|---|
| Maximum heating power (total) | share in % | Hour with the highest aggregated heating power of all consumers in the year; the share scales the power. |
| Maximum heating power per month | month | Peak hour of the selected month. |
| Maximum heating power per day | date | Peak hour of the selected day. |
| Heating power at point in time | date and hour | exactly the selected point in time. |
| Connection load (nominal) | share in % | Nominal connection load of each consumer (design state); simultaneity and part load are not applied, the supply temperature corresponds to the maximum of the heating curve. |
| Maximum cooling power (total) | share in % | Hour with the highest aggregated cooling power in the year. |
For the demand-based modes, the powers are determined from the building demand profiles at the respective peak hour; time shifts from simultaneity and part-load factors of the consumers are applied. The supply temperature follows from the heating curve at the outdoor temperature of the peak hour. In cold district heating networks (5GDHC), the Connection load mode is not available.
Practical tip:
Set up several operating points in one run – they are calculated in parallel and deliver the entire operating spectrum in a single pass. A proven combination is Connection load (nominal) for the pure design and Maximum heating power (total) for the realistic annual peak. If an operating point does not converge, first increase the Simulation time before adjusting other parameters.
Start, Progress and Cancellation
The 
Calculate button starts the calculation:
- A solver model is created for each operating point in the project directory.
- The solvers run in parallel; the progress bar shows the averaged progress of all operating points.
- After completion, the results are loaded, saved with the project and the result view is updated.
During the calculation, the Cancel button next to the progress bar aborts the running solvers. The maximum computation time per solver run can be adjusted in the program settings under Solver timeout. If Close dialog after completion is enabled (default), the dialog closes automatically after a successful calculation.
Notes
- If a solver run fails, the error message offers to display the solver log file directly.
- Operating points with warnings (non-converged nodes, very low temperatures, deviation from the target temperature or target pressure difference at the worst point) are marked in the operating-point list; a detail dialog lists recommended solutions, e.g. increase the power of the heat generators, adjust pump characteristic curves, enlarge pipe diameters or increase the simulation time.
- After changes to the network, the note “Network has been changed - results may be outdated” appears — then repeat the calculation.