The IfcSharedBldgServiceElements schema in the interoperability layer defines basic concepts required for interoperability primarily between Building Service domain extensions, notably IfcHvacDomain, IfcPlumbingFireProtectionDomain, IfcElectricalDomain and IfcBuildingControlsDomain. This schema includes concepts such as basic type and occurrence definitions for flow and distribution systems and property sets for common building service scenarios such as fluid-flow properties, electrical properties, and space thermal properties.
Figure 234 illustrates the concepts of type, occurrence and performance. Types are specializations of IfcDistributionElementType while occurrences are specializations of IfcDistributionElement. A third theme, defined in the IfcControlExtension schema, relates to the performance characteristics of an occurrence using instances of the IfcPerformanceHistory entity.
A type can have zero or many occurrences. Each occurrence can have many performance history entities associated with it, allowing data that is specific to a certain phase of the lifecycle to be captured and maintained throughout the life of the dataset.
Figure 234 — Building service lifecycle
The IfcSharedBldgServiceElements schema specializes building services concepts symmetrically for occurrences and types, with the primary functional role of the entity determining its classification into the following generic concepts:
Refer to the domain schemas where types and occurrences are further elaborated using PredefinedType enumerations for examples of the range of supported concepts within these broad classifications. If a new type is needed within this classification, extend using the ElementType attribute. However, if a completely new concept is required that does not fit within this classification, use instances of the generic IfcDistributionElementType and IfcDistributionElement entities for the type/occurrence objects as needed.
Occurrences in a distribution system are typically coupled together using instances of IfcDistributionPort. This is also where concepts such as mass-flow properties are applied based on performance characteristics. Refer to the IfcDistributionPort documentation within this schema for further elaboration on coupling together components in a distribution system and tracking the flow characteristics across the port boundaries.
HISTORY This schema has been significantly modified in IFC2x2. Refer to the change log and issues resolution database for details.