Heating, ventilation and air-conditioning (HVAC) systems play an important role in energy and air flow in most modern buildings, and are responsible for an accordingly large share of energy consumption.
Equation-based modeling allows the individual equations describing component behavior to be combined and modified. With component behavior being described by equations, variables do not need to be inputs or outputs anymore, which makes it possible to model situations of flow reversal in an easier way than with typical component-based models. The flexibility of equation-based modeling has been praised for particular applications such as the modeling of controls in HVAC simulation.