Definition from IAI:
This class defines elements of a building automation control system that are used to
impart control over elements of a distribution system.
This class defines elements of a building automation control system. These
are typically used to control distribution system elements to maintain
temperature, humidity, pressure,
flow, power, lighting levels, etc., through the modulation, staging or sequencing
of mechanical or electrical devices. The three general functional categories of
ControlElements as defined for this release of the IFC model are as follows:
- Impart control over flow control elements (IfcFlowController) in a
distribution system such as dampers, valves, relays, etc., typically through
the use of actuation (IfcActuator: See IfcHvacDomain schema).
- Sensing elements (IfcSensor: See IfcHvacDomain schema) that measure changes
in the controlled variable (e.g., temperature, humidity, pressure, flow,
etc.).
- Controllers (IfcController: See IfcHvacDomain schema) typically classified
according to the control action they seek to perform and generally responsible
for making decisions about the elements under control.
Since this class and its subtypes typically relate to many different distribution
flow elements (IfcDistributionFlowElement), the objectified relationship
IfcRelFlowControlElements has been provided to relate control and flow elements
as required.
HISTORY: New entity in IFC R2.0.
ISSUES: See issues and change log for changes made in IFC R2x.
Geometry Use Definitions
The geometric representation of IfcControlElement is given
by the IfcProductDefinitionShape, allowing multiple geometric
representations. Included are:
Local Placement
The local placement is defined in the supertype IfcProduct. It
is defined by a subtype of IfcObjectPlacement which can define
an absolute placement, relative placement, or grid reference, with each
defining the local coordinate system referenced by all geometric
representations. The PlacementRelTo relationship of IfcLocalPlacement,
if given, shall point to the same IfcSpatialStructureElement which
is used in the ContainedInStructure inverse attribute, or to a referenced
spatial structure element at a higher level. If the relative
placement is not used, the absolute placement is defined
within the world coordinate system.
Informal propositions for local placement:
- If the LocalPlacement is specified,
then all aggregated components should use this placement as
their relative placement.
Standard Geometric Representation
Currently, the use of attribute driven geometry for this class
is not supported. The standard geometric representation is
defined using explicit geometry.
B-Rep Representation
The faceted B-Rep capabilities (with or without voids) shall be
supported for B-Rep representation.
