Beneath the room nodes (thermal zones) the air flow model needs additional auxiliary nodes for the ventilation duct network as junctions of the individual parts of the duct system. In order to keep the thermal model small these nodes are not modeled as thermal zones in Type 56.

The temperatures of the auxiliary nodes are directly calculated from the temperatures of the joining air flows. Thermal capacitance or other heat gains or losses of these nodes are not considered. In the thermal model air flows of the auxiliary nodes into the space zones are interpreted as ventilations.

To model an air heater or cooler, resp. a humidifier or dehumidifier, temperature as well as humidity can be defined for an auxiliary node by means of a constant, input or schedule variable. The power necessary to reach this set point for the air can be obtained by an output.

Figure 6 shows an example for the illustration of a duct network. The reference temperature of 20°C is defined for the auxiliary node AN6. For Room3 results a ventilation of 33kg/s with 17.9°C. Rooml and Room2 have zero ventilation.

Resulting temperature of aux. nodes

Aux. nodes Temperature [°C]

AN1 18.8

AN2 17.9

AN3 17.9

AN4 18.0

AN5 15.0