User Guide — Buildings Library User Guide

# User Guide

This user guide provides instructions for how to use the free open-source Modelica Buildings library. The user guide covers how to

- get started,
- follow best practices when createing models and running simulations,
- fix common problems in translating or simulating models,
- automate pre- and post-processing of model inputs and outputs,
- develop and contribute new models to the library, and
- get help.

The following information can be found in the Modelica files rather than in this documentation:

- The physical assumptions and the equations that the models are based on.
- Advice as to which models may be used if multiple models may be available for similar equipment or physical phenomena.

## Contents

- 1. Getting Started
  - 1.1. Literature for Users
  - 1.2. Literature for Developers
  - 1.3. Software Requirements
  - 1.4. Running the First Simulations
  - 1.5. References
- 2. Best Practice
  - 2.1. Organization of packages
  - 2.2. Building large system models
  - 2.3. Propagating parameters and media packages
  - 2.4. Thermo-fluid systems
    - 2.4.1. Overdetermined initialization problem and inconsistent equations
    - 2.4.2. Modeling of fluid junctions
    - 2.4.3. Use of sensors in fluid flow systems
    - 2.4.4. Reference pressure for incompressible fluids such as water
    - 2.4.5. Nominal Values
  - 2.5. Start values of iteration variables
  - 2.6. Avoiding events
  - 2.7. Controls
  - 2.8. Examples for how to debug and correct slow simulations
    - 2.8.1. State events
    - 2.8.2. State variables that dominate the error control
  - 2.9. Numerical solvers
- 3. Work-Arounds
  - 3.1. Avoiding step changes
  - 3.2. Breaking algebraic loops
  - 3.3. Reducing nonlinear equations of serially connected flow resistances
  - 3.4. Prescribed mass flow rate
  - 3.5. Avoiding overspecified initialization problems
- 4. Pre- and Post-Processing
- 5. Development
  - 5.1. Contributing
  - 5.2. Adding a new class
    - 5.2.1. Thermofluid flow device
    - 5.2.2. Pressure drop
- 6. Help
- 7. Glossary
- 8. Acknowledgments
- 9. Disclaimers
- 10. Copyright and License

## Indices and tables

- Index
- Module Index
- Search Page