Space

Definition

The concept of 'Space' is very central to the current implementations. Spaces are a good mechanism for giving the building a lot of structure - other objects can be contained by spaces, referenced by spaces or aligned to spaces. Using spaces in this manner is an important step from the CAD / geometry centered way of thinking to a way that is more information oriented. With spaces it would be possible to build a rich information model that doesn't contain any geometry at all (although this is not what we aim to do)

Although spaces are already very useful there are some quite important limitations. The space geometry is a singe extruded boundary polyline that can't have voids. It is not possible to model a large space that totally encloses another smaller space. The space boundaries are also quite limited and can't be used for e.g. material quantities if there is more than one surface material per space boundary.

The difference between 'Space occupancy' and 'Space occupant' might need some explanation.

• 'Space occupancy' is the number of occupants in the space; the number can be used for HVAC simulations and fire escape planning. It also has a provision to store a cumulative occupancy number and other more detailed information needed by these applications.
• 'Space occupant' is the actual occupant for the space for FM purposes. The occupant is a person or organization and it can contain any data provided by these concepts, such as an address and the actor role.

Geometry

Geometry type	Extrusion	Profile	Segments	Clipped	Slanted
BoundingBox
Extruded solid	Linear	Rectangular	1	No	No
Extruded solid	Linear	Arbitrary	1	No	No
Extruded solid	Linear	Curved	1	No	No
Extruded solid	Linear	Rectangular	1	Yes	No
Extruded solid	Linear	Arbitrary	1	Yes	No
Extruded solid	Linear	Curved	1	Yes	No

• Not slanted in the context of spaces means, that the extrusion is in the direction of the global Z-axis
• As the basic representation spaces should always have a bounding box. The bounding box can be used as a place holder for spaces with complex geometry in programs that are not able to support the given geometry. This could be the case e.g. in programs that don't support spaces with curved boundaries.
• For spaces the footprint of the space is very important. The footprint of a space is the plan view geometry that gives the shape and location of the space. The footprint is also used to calculate the area and perimeter of the space. When using an extruded solid the footprint of the space is equal to the extrusion profile.
• Because the Brep representation is not able to clearly define which part is the footprint of the space the combination of bounding box and Brep is not allowed. If a Brep representation is given for the space then it must also have the bounding box and an extruded solid defining the footprint. If the extrusion depth of the solid is zero this means that the solid is only used to communicate the footprint.
• The solid geometry of a space contains only one solid with one segment and the space can't contain voids. This means that door and window reveals and other similar additions to the space are not included in the IFC file.
• It is not possible to use geometry that takes into account the columns and other building elements in the space.
• The doors, windows, columns and other elements may however contain logical relationships to the space, which makes it possible for the receiving application to make more advanced area, volume etc. calculations.
• If there is need to make a round (circular) or elliptical space the profile can be defined using the IfcCompositeCurve.
• If the space has a boundary that uses a spline, nurb etc. the curve has to be approximated using straight segments.
• The solid geometry for spaces may be clipped in any way that does not affect the footprint of the space. It is not allowed for example to make a rectangular extrusion for a space and to clip it to form a L-shape.

View considerations

• Arch. design >> Quantities take off / cost estimating
  • Space area
  • Space use type (office, restroom etc.)
  • Objects contained or referenced by a space
  • Space surfaces (only very limited support at the moment)
• Arch. design >> Thermal load calculations / HVAC system design
  • Space area and volume
  • Space use type (office, restroom etc.)
  • Heat loads (people, equipment etc.)
  • Space boundaries, relationships to the bounding elements and other spaces
  • Openings in the space boundaries (openings, doors and windows)
• FM
  • Can't be done without spaces

Documents

• IFCR2_IfcSpace_991026_jh.pdf
• IFCR2_SpaceToWallConnection_991026_jh.pdf
• IFCR2_AssigningDoorsAndWindowsToSpaces_991217_jh.pdf
• IFCR2_Label_000331_jh.pdf

Used by views

• This concept is used by all views.

Data structure

IfcSpace
GlobalId
OwnerHistory
Owner history [all]
Label
PartOfGroups
Grouping [1,2]
Grouping : Zones [1,3]
Contains
Containment : Referencing [1,2,3]
RelatedObjects
Simple door [1,3,5]
Simple window [1,3,5]
Containment [all]
RelatedObjects
Furniture [1]
Electrical appliance [1,3]
Plumbing fixture [2]
Counter or shelf [1]
Cabinet [1]
Electrical fixture [1]
IsContainedBy
Containment [all]
RelatingObject
Building storey [all]
IsDefinedBy
Dynamic property assignment [all]
RelatingPropertyDefinition
Space occupancy [3]
PropertySet system [all]
HasProperties
Space thermal properties [3]
Space program properties [4]
Space type [4]
IsActedUpon
Space occupant [none]
LocalPlacement
Relative placement [all]
PlacementRelTo
Building storey [all]
Representations
Geometric representation [all]
Items
Bounding box geometry [all]
Extruded solid: rectangular [1,3,5]
Extruded solid: arbitrary [all]
Extruded solid: curved [1,2,3,5]
Extruded solid: rectangular, clipped [3,5]
Extruded solid: arbitrary, clipped [3,5]
Extruded solid: curved, clipped [3,5]
Classification
Classification assignment [none]
Classifications
Classification [none]
BoundedBy
Space boundary [1,3]
InteriorOrExteriorSpace
IfcInternalOrExternalEnum
Internal
External
SpaceReference
SpaceName
calcTotalPerimeter
calcTotalArea
calcTotalVolume
calcAverageHeight

Uses concepts

Bounding box geometry [all]
Building storey [all]
Cabinet [1]
Classification [none]
Classification assignment [none]
Containment [all]
Containment : Referencing [1,2,3]
Counter or shelf [1]
Dynamic property assignment [all]
Electrical appliance [1,3]
Electrical fixture [1]
Extruded solid: arbitrary [all]
Extruded solid: arbitrary, clipped [3,5]
Extruded solid: curved [1,2,3,5]
Extruded solid: curved, clipped [3,5]
Extruded solid: rectangular [1,3,5]
Extruded solid: rectangular, clipped [3,5]
Furniture [1]
Geometric representation [all]
Grouping [1,2]
Grouping : Zones [1,3]
Owner history [all]
Plumbing fixture [2]
PropertySet system [all]
Relative placement [all]
Simple door [1,3,5]
Simple window [1,3,5]
Space boundary [1,3]
Space occupancy [3]
Space occupant [none]
Space program properties [4]
Space thermal properties [3]
Space type [4]

Used by concepts

Cabinet
Counter or shelf
Electrical appliance
Electrical fixture
Flow controller
Flow equipment
Flow fitting
Flow segment
Flow terminal
Furniture
Plumbing fixture
Proxy [product with geometry]
Simple door
Simple window
Space boundary
Space occupant

Copyright © 2000-2002 BLIS-Project [BLIS, Registered Organization]
Author: Jiri Hietanen (jiri@blis-project.org)
All rights reserved.