packageUsersGuide

Information

The package Buildings.Controls.OBC contains the Control Description Language (CDL) and models for building control that are implemented using CDL. The Control Description Language is a language that is being standardized through ASHRAE Standard 231P. It has been developed to digitalize the design, implementation and commissioning of building control sequences in format that is independent of any particular control product line (Wetter et al., 2018). For a description of the process for digitalizing control delivery, see Wetter et al. (2022).

The Control Description Language and the library of control sequences have been developed in the OpenBuildingControl project, see obc.lbl.gov.

This package contains control sequences for

• HVAC airside system control Buildings.Controls.OBC.ASHRAE.G36,
• radiant heating and cooling systems Buildings.Controls.OBC.RadiantSystems,
• outdoor lighting control Buildings.Controls.OBC.OutdoorLights, and
• shading device control Buildings.Controls.OBC.Shade.

The control sequences are composed of the elementary blocks from the package Buildings.Controls.OBC.CDL.

The package also contains models for unit conversions, Buildings.Controls.OBC.UnitConversions, and utilities models, such as Buildings.Controls.OBC.Utilities.OptimalStart, which output the optimal start time for an HVAC system.

The Control Description Language (CDL) can be found in Buildings.Controls.OBC.CDL and its specification is at obc.lbl.gov. Note that the implementation in Buildings.Controls.OBC.CDL replicates some classes from the Modelica Standard Library. This was done to have a self-contained implementation of CDL that can be standardized through ASHRAE and that has minimum dependencies on other software to ease support by building automation systems. The replication of the implementation of the blocks also avoids that CDL inadvertently changes if the Modelica Standard Library is updated, which is undesirable as changes to CDL will need to go through the ASHRAE standardization process.

References

• Michael Wetter, Milica Grahovac and Jianjun Hu.
  Control Description Language.
  1st American Modelica Conference, Cambridge, MA, USA, August 2018.
  https://doi.org/10.3384/ecp1815417.
• Michael Wetter, Paul Ehrlich, Antoine Gautier, Milica Grahovac, Philip Haves, Jianjun Hu, Anand Prakash, Dave Robin and Kun Zhang.
  OpenBuildingControl: Digitizing the control delivery from building energy modeling to specification, implementation and formal verification.
  Energy, Volume 238, Part A, January 2022.
  https://doi.org/10.1016/j.energy.2021.121501.

Contents

Name	Description
Conventions	Naming conventions in OBC package