See Generic Air Loop Tutorial
Air handling units (AHUs) are components that are automatically included in the supply sub-loops of all air loops. AHUs are composite units incorporating all of the components that comprise central air handling plant such as outdoor air mixers, fans, heating/ cooling coils and humidifiers. There are two main types of AHU in DesignBuilder HVAC, generic and unitary AHUs. The main difference between the two units is that unitary AHUs incorporate an EnergyPlus unitary system such as air-to-air heat pump or heat/cool unit.
To edit the data associated with an AHU, you first need to be at the supply sub loop level of the Air loop. Select the AHU component by moving the mouse cursor over it and then clicking the mouse button to select it. You can then access the edit dialog by right-clicking the mouse and selecting the Edit selected component option or alternatively, select the Edit selected component tool from the toolbar.
These AHU types are available: