HVAC and Control Templates for the Modelica Buildings Library

This article reports on our experience in creating Modelica classes that serve as templates for modeling HVAC systems with thousands of configurations and closed-loop controls. Our motivation is to reduce model creation and parameterization time, provide access to state-of-the-art control sequences, while limiting the risk of error and enforcing modeling best practices. The development of such templates required exploration of class parameterization techniques and data structures for handling large sets of equipment parameters. By describing these issues and the approach taken, we show how the Modelica language can support advanced templating logic. The main limitation we encountered relates to parameter assignment and propagation. The interpretation of parameter attributes at user interface runtime, or the handling of non-trivial constructs involving record classes at compile time is not consistently supported by Modelica tools. This leads to choices that are difficult to make when looking for a generic implementation.