## 7.1 IfcBuildingControlsDomain

### 7.1.1 Schema Definition

The IfcBuildingControlsDomain schema forms part of the Domain Layer of the IFC Model. It extends the ideas concerning building services outlined in the IfcSharedBldgServicesElements schema. It defines concepts of building automation, control, instrumentation and alarm.

The IfcBuildingControlsDomain schema supports ideas including types and occurrences of:

- actuator
- alarm
- controller
- sensor
- flow instrument
- unitary control element

Elements that perform the control action such as valves and dampers are principally types of distribution flow element and are located in the IfcHvacDomain and IfcElectricalDomain schemas.

Occurrences of control elements capture design information, while realtime device state is captured on IfcPerformanceHistory, for which control elements may be assigned. Various standard property sets are defined for performance history to capture direct control data.

Control elements are identified within control systems using IfcRelAssociatesClassification to indicate URLs of gateways and addresses of devices and data points.

To support multiple lifecycle stages, realtime control data (IfcPerformanceHistory) and design data (IfcDistributionElement subtypes) are separate such that each may be used independently without the existence of the other, however both may be related via IfcRelAssignsToControl. If device addressing is known at the time of design where classification is applied to occurrence entities, then upon connecting to a control system the control element occurrences can be assigned to realtime device data (IfcPerformanceHistory) automatically according to matching classification.

To connect control elements to physical flow elements measured or controlled, the IfcRelFlowControlElements relationship is used. For example, such relationship may map an actuator to a damper, or a temperature sensor to an evaporator coil. Performance data for IfcDistributionFlowElement entities may be derived by traversing such relationships.

The IfcBuildingControlsDomain schema does not specify building automation protocols, but may be mapped to standard protocols or vendor implementations for commissioning and operations interoperability. Common applicable entities are described as follows:

- IfcPerformanceHistory: Captures realtime device data in the form of property sets.
- IfcPropertySet: Captures a set of realtime device data, either using predefined data structures or custom information.
- IfcPropertySetTemplate: Captures metadata about custom properties, such as names, descriptions, data types, units, and ranges.
- IfcRelAssociatesClassification: Associates addresses of devices and control points to uniquely identify within a control system.
- IfcController: Captures non-realtime occurrence information for hardware or software-based arbitrary analog and digital data.
- IfcAlarm: Captures non-realtime occurrence information for hardware or software-based alarm sources.
- IfcEvent: Captures alarm event handling information.
- IfcProcedure: Captures device procedures that may be run arbitrarily or in response to events.
- IfcTask: Captures device programs that may be scheduled at various times.

> HISTORY New schema in IFC2x2.

EXPRESS-G diagram