The Modelica Buildings library is a free open-source library with dynamic simulation models for building energy and control systems. The library contains models for

• air-based HVAC systems,
• chilled water plants,
• water-based heating systems,
• controls,
• heat transfer among rooms and the outside,
• multizone airflow, including natural ventilation and contaminant transport,
• single-zone computational fluid dynamics coupled to heat transfer and HVAC systems,
• data-driven load prediction for demand response applications, and
• electrical DC and AC systems with two- or three-phases that can be balanced and unbalanced.

The primary use of the library is for flexible and fast modeling of building energy and control systems to accelerate innovation leading to cost-effective very low energy systems for new and existing buildings. The library is particularly suited for

• rapid prototyping of new building systems,
• analysis of the operation of existing building systems,
• development, specification, verification and deployment of building controls within a model-based design process, and
• reuse of models during operation for functional testing, for verification of control sequences, for energy-minimizing controls, fault detection and diagnostics.