Building Controls Virtual Test Bed

The Building Controls Virtual Test Bed (BCVTB) is a software environment that allows expert users to couple different simulation programs for co-simulation, and to couple simulation programs with actual hardware. For example, the BCVTB allows to simulate a building in EnergyPlus and the HVAC and control system in Modelica, while exchanging data between the software as they simulate. The BCVTB is based on the Ptolemy II software environment. The BCVTB allows expert users of simulation to expand the capabilities of individual programs by linking them to other programs. Due to the different programs that may be involved in distributed simulation, familiarity with configuring programs is essential.

Programs that are linked to the BCVTB are

• the EnergyPlus whole building energy simulation program,

• the Modelica modeling and simulation environment Dymola,

• the MATLAB and Simulink tools for scientific computing,

• the Radiance ray-tracing software for lighting analysis,

• the ESP-r integrated building energy modeling program,

• the TRNSYS system simulation program,

• Functional Mock-up Units (FMU) for co-simulation and model-exchange,

• the BACnet stack, which allows exchanging data with BACnet compliant Building Automation System (BAS),

• the analog/digital interface USB-1208LS from Measurement Computing Corporation that can be connected to a USB port.

In addition to using programs that are coupled to Ptolemy II, Ptolemy II's graphical modeling environment can also be used to define models for control systems, for physical devices, for communication systems or for post-processing and real-time visualization.

Typical applications of the BCVTB include:

• performance assessment of integrated building energy and controls systems,
• development of new controls algorithms, and
• formal verification of controls algorithms prior to deployment in a building in order to reduce commissioning time.

The coupling of Modelica allows using EnergyPlus for modeling the building heat flow and daylight availability and using Modelica to model innovative building energy and control systems based on the library that is currently in development at http://simulationresearch.lbl.gov/modelica. This allows advanced users to

• define on the fly new HVAC components and systems in a modular, hierarchical, object-oriented, equation-based graphical modeling environment and couple them to EnergyPlus,

• innovate new HVAC system and control architectures for which models do not yet exist in off-the-shelve building simulation programs,
• analyze dynamic effects of HVAC systems, modeled in Modelica, and their local and supervisory control loops, modeled in MATLAB/Simulink, Modelica or Ptolemy, and
• simulate virtual experiments prior to full-scale testing in a laboratory or a real building in order to determine the range of required boundary conditions, the type of experiments that need to be conducted and, for example, to improve a control logic in simulation where iterations can be made faster than in an actual experiment.

Contact

Michael Wetter, Thierry S. Nouidui and Philip Haves
Lawrence Berkeley National Laboratory
Building Technologies Department
{MWetter,TSNouidui,PHaves}@lbl.gov

Acknowledgements

This research was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Building Technologies of the U.S. Department of Energy, under Contract No. DE-AC02-05CH11231.

Special thanks go to Prof. Edward A. Lee and Christopher Brooks from the University of California at Berkeley for their support in integrating the BCVTB functionality into the Ptolemy II software, and implementing the Functional Mock-up Unit for co-simulation import interface in the BCVTB.

We would also like to thank

• Timothy P. McDowell from Thermal Energy System Specialists (TESS) for the implementation of the TRNSYS interface.

• Pieter-Jan Hoes and Roel Loonen from the Technical University of Eindhoven for the implementation of the ESP-r interface.

• Gregor Henze, Charles Corbin, Anthony Florita and Peter May-Ostendorp from the University of Colorado at Boulder for their contributions to the MATLAB interface and the EnergyPlus 3.0 upgrade.

• Rui Zhang from Carnegie Mellon for her contributions to the Windows configuration and the EnergyPlus 3.1 upgrade.

• Zhengwei Li from the Georgia Institute of Technology for the implementation of the BACnet interface.

• Andrew McNeil from LBNL for providing the Radiance example.