#### 5.4.3.1 IfcBuilding

| Bâtiment
| Gebäude

A building represents a structure that provides shelter for its occupants or contents and stands in one place. The building is also used to provide a basic element within the spatial structure hierarchy for the components of a building project (together with site, storey, and space).

> NOTE Definition from ISO 6707-1:
> Construction work that has the provision of shelter for its occupants or contents as one of its main purpose and is normally designed to stand permanently in one place.

A building is (if specified) associated to a site. A building may span over several connected or disconnected buildings. Therefore building complex provides for a collection of buildings included in a site. A building can also be decomposed in (vertical) parts, where each part defines a building section. This is defined by the composition type attribute of the supertype IfcSpatialStructureElements which is interpreted as follow:

- COMPLEX: building complex
- ELEMENT: building
- PARTIAL: building section

The IfcBuilding is used to build the spatial structure of a building (that serves as the primary project breakdown and is required to be hierarchical). The spatial structure elements are linked together by using the objectified relationship IfcRelAggregates.

> HISTORY New entity in IFC1.0.

Figure 45 shows the IfcBuilding as part of the spatial structure. It also serves as the spatial container for building and other elements.

> NOTE Detailed requirements on mandatory element containment and placement structure relationships are given in view definitions and implementer agreements.

Figure 45 — Building composition

Systems, such as building service or electrical distribution systems, zonal systems, or structural analysis systems, relate to IfcBuilding by using the objectified relationship IfcRelServicesBuildings.

Attribute Use Definition

Figure 46 describes the heights and elevations of the IfcBuilding. It is used to provide the height above sea level of the project height datum for this building, that is, the internal height 0.00. The height 0.00 is often used as a building internal reference height and equal to the floor finish level of the ground floor.

- base elevation of building provided by: IfcBuilding.ElevationOfRefHeight, it is usually the top of construction slab
- base elevation of terrain at the perimeter of the building provided by: IfcBuilding.ElevationOfTerrain, it is usually the minimum elevation is sloped terrain
- total height of building, also referred to as ridge height (top of roof structure, e.g the ridge against terrain): provided by BaseQuantity with Name="TotalHeight"
- eaves height of building (base of roof structure, e.g the eaves against terrain): provided by BaseQuantity with Name="EavesHeight"

Figure 46 — Building elevations

## Building Automation

The following concepts are inherited at supertypes:

- IfcRoot: Revision Control

Instance diagram

Identity

The Identity concept applies to this entity.

Exchange |  |  |  |  |
--- | --- | --- | --- | --- | ---
Import |  |  |  |  |
Export |  |  |  |  |

Object Aggregation

The Object Aggregation concept applies to this entity as shown in Table 16.

PredefinedType | RelatedObjects
--- | ---
| IfcBuildingStorey
Table 16 — IfcBuilding Object Aggregation

Exchange |  |  |  |  |
--- | --- | --- | --- | --- | ---
Import |  |  |  |  |
Export |  |  |  |  |

XSD Specification:

<xs:element name="IfcBuilding" type="ifc:IfcBuilding" substitutionGroup="ifc:IfcSpatialStructureElement" nillable="true"/>
<xs:complexType name="IfcBuilding">
<xs:complexContent>
<xs:extension base="ifc:IfcSpatialStructureElement"/>
</xs:complexContent>
</xs:complexType>

EXPRESS Specification:

ENTITY IfcBuilding

| SUBTYPE OF IfcSpatialStructureElement;

ElevationOfRefHeight | : | OPTIONAL IfcLengthMeasure;
ElevationOfTerrain | : | OPTIONAL IfcLengthMeasure;
BuildingAddress | : | OPTIONAL IfcStrippedOptional;

END_ENTITY;

EXPRESS-G diagram

Attribute Definitions:

ElevationOfRefHeight | : | Elevation above sea level of the reference height used for all storey elevation measures, equals to height 0.0. It is usually the ground floor level.
ElevationOfTerrain | : | Elevation above the minimal terrain level around the foot print of the building, given in elevation above sea level.

Inheritance Graph:

ENTITY IfcBuilding

| ENTITY IfcRoot

GlobalId | : | IfcGloballyUniqueId;
OwnerHistory | : | OPTIONAL IfcOwnerHistory;
Name | : | OPTIONAL IfcLabel;
Description | : | OPTIONAL IfcText;

| ENTITY IfcObjectDefinition

| INVERSE

HasAssignments | : | SET OF IfcRelAssigns FOR RelatedObjects;
Nests | : | SET [0:1] OF IfcRelNests FOR RelatedObjects;
IsNestedBy | : | SET OF IfcRelNests FOR RelatingObject;
HasContext | : | SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions;
IsDecomposedBy | : | SET OF IfcRelAggregates FOR RelatingObject;
Decomposes | : | SET [0:1] OF IfcRelAggregates FOR RelatedObjects;
HasAssociations | : | SET OF IfcRelAssociates FOR RelatedObjects;

| ENTITY IfcObject

ObjectType | : | OPTIONAL IfcLabel;

| INVERSE

IsDeclaredBy | : | SET [0:1] OF IfcRelDefinesByObject FOR RelatedObjects;
Declares | : | SET OF IfcRelDefinesByObject FOR RelatingObject;
IsTypedBy | : | SET [0:1] OF IfcRelDefinesByType FOR RelatedObjects;
IsDefinedBy | : | SET OF IfcRelDefinesByProperties FOR RelatedObjects;

| ENTITY IfcProduct

ObjectPlacement | : | OPTIONAL IfcObjectPlacement;
Representation | : | OPTIONAL IfcStrippedOptional;

| INVERSE

ReferencedBy | : | SET OF IfcRelAssignsToProduct FOR RelatingProduct;

| ENTITY IfcSpatialElement

LongName | : | OPTIONAL IfcLabel;

| INVERSE

ContainsElements | : | SET OF IfcRelContainedInSpatialStructure FOR RelatingStructure;

| ENTITY IfcSpatialStructureElement

CompositionType | : | OPTIONAL IfcStrippedOptional;

| ENTITY IfcBuilding

ElevationOfRefHeight | : | OPTIONAL IfcLengthMeasure;
ElevationOfTerrain | : | OPTIONAL IfcLengthMeasure;
BuildingAddress | : | OPTIONAL IfcStrippedOptional;

END_ENTITY;

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