To ensure building controls can be optimized by central systems, primary systems and individual room automation, it is essential that:

  • Individual BACnet objects are grouped together to facilitate optimization of building systems.
  • Room operating functions are governed by the following room automation operating modes: Room operating mode, Plant operating mode, and HVAC device mode.

Room and Room segments

An application type is composed of various modules (application functions, AF) that coordinate common functions and control devices. There are two general, large collections of these application function; one named Room and the other Room segment. This is helpful to know when you are trying to find and use various features.

Depending on the application being used and its supported features, the Room AFs provide coordination between various control devices and functions such as:

  • Plant operation mode
  • Room operation mode
  • Setpoint determination
  • Room cooling PID or Staged controller
  • Room heating PID or Staged controller
  • Room ventilation controller
  • Dehumidification PID controller
  • Heating/cooling state determination

The Room segment application functions control individual HVAC devices (for example, heating coil, supply damper, and so on). Although a room usually has only one room segment, multiple segments can be controlled and coordinated by a single room.


To manage these many entities and to facilitate central control functions, a grouping mechanism has been applied to organize these functions by enabling group collaboration, (that is, the data exchange between the central control functions (group masters) and individual entities (group members).

Room and Room segment groups allow the central control and coordination of different building systems, zones, areas. Typical central control functions are:

  • Central operating mode – from operating station or a scheduler, distributed to connected rooms.
  • HVAC emergency – coordinates emergency functions in zones and controls the HVAC devices according to the emergency mode.
  • Central HVAC functions – collects demand signals from rooms using grouping mechanism and provides the setpoint and supply chain demand to the central plants (for example, chilled water, hot water or air handling unit). DXRs can also be used without leveraging central functions by programming at the supervisory controller.