How to prepare IFC files in Revit / Archicad for Thermal calculations in InstalSystem 5 (for architects and BIM coordinators)

Product	InstalSystem 5
Type of article	TIP&TRICK
Source for translation	2026-03-03

Problem description

To ensure the accurate creation of the thermal model of a building and the recognition of automatic rooms, it is necessary to correctly interpret architectural elements from Revit / Archicad into native InstalSystem 5 elements. For more information, see: BIM - Interpretation of IFC elements into building structure elements.
Therefore, a BIM model, created in Revit / Archicad, should be properly prepared for export.

Solution

Basic recommendations for optimizing the preparation of BIM models for the exporting to InstalSystem 5

• For best results, export only the relevant elements needed for Thermal calculations of building. Avoid exporting unnecessary architectural and structural details (furniture, elements protruding beyond the actual building structure, decorative architectural elements, grids, roof fittings) and external elements (roads, sidewalks, trees, walls) by setting the type to Not Exported / Export to IFC - No.
  Elements such as beams (IfcBeam) or ramps should be excluded unless they are integral to the thermal analysis;
• Export only elements that enclose space, such as walls (ifcWall), ceilings (ifcSlab), roofs (ifcRoof), windows (ifcWindow), and doors (ifcDoor). These elements must form a sealed geometry (the "closed box" principle) that will allow recognizing automatic rooms in InstalSystem 5;
• Select export settings that will ensure a small file size, avoid overly detailed geometry or exporting unnecessary parameters;
• Models and their elements should be simplified as much as possible - combine multi-layered elements such as walls, slabs, and roofs if their layers form independent, contiguous elements;
• Ensure proper element mapping (mapping settings):

IFC element	InstalSystem 5 element
ifcWall / ifcWallStandardCase	Wall
ifcCurtainWall	Curtain Wall
ifcSlab	Slab
ifcRoof	Roof
ifcWindow / ifcDoor / ifcOpeningElement	Window / Door / Opening in wall
ifcSpace	Room (manual)

Export Storeys (IfcBuildingStorey)

• Storeys should be created and exported in accordance with the logic of InstalSystem 5: each Storey contains such elements as Slab, Wall and Roof (on the top Storey).
  For more information, see: Creating a storey and
  For more information, see: BIM - Creating storeys based on data from IFC model;
• Avoid situations where Slab and Roof elements form separate Storey. Such export creates unnecessary, redundant Storey, which complicates the subsequent IFC (BIM) building data interpretation.
  

Export architectural elements

Export Wall (IfcWall)

• Agree on one type of wall as ifcWall (instead of ifcWall and ifcWallStandardCase);
• Avoid exporting Wall elements that are not necessary for Thermal calculations of building (e.g. retaining walls, walls located outside the thermal contour of the building);
• Wall elements should not pass through multiple Storeys: each Wall should start and end on the same Storey and should be aligned with the Storey elevations. There should be no gaps between the Wall and the storey Slab / Roof;
• Avoid multi-layer / adjacent Wall - export Wall as a single element (IfcWall), without separate structural layers,
• Avoid Wall elements intersecting or overlapping each other;
• Avoid Wall elements containing each other;
• Avoid rhomboidal Wall - in 3D view, the Wall should form a simple quadrangular facet with a rectangle base, the beginning and end of the Wall should form right angles to the longer edge of the Wall;
• The Wall on the side view must be rectangular - an irregularly shaped Wall (when viewed from the side) will be recognized by the geometry defined by "Bounding Box Length / Width / Height". In this case, each protruding fragment will increase the size of such a wall, as the program will attempt to create a uniform rectangular parallelepiped. A Opening in wall will behave similarly, in accordance with the rules of "Bounding Box Length / Width / Height";
• Possibility to export a triangular Wall (or other shape) if it is ultimately cut by the Roof - such Wall will be recognized as a parallelepiped. After inserting the Roof and performing Calculations, InstalSystem 5 will cut the upper part of such Wall accordingly;
• Avoid Wall cut out in the middle by modelling geometry if there are no Window, or Opening in wall there - InstalSystem 5 will fill such openings in accordance with the "Bounding Box Length / Width / Height" rule, assuming that there will be elements such as Window, or Opening in wall there;
• Avoid L-shaped, U-shaped or similar Wall - each change in Wall direction as a separate ifcWall element;
• Avoid export of ifcBeam and ifcColumn - if the absence of these elements does not affect thermal calculations, they should be excluded from export;
• Avoid arched Wall - such Wall should be excluded from export and nativly modeled in InstalSystem 5;
• Enclosed space - Wall elements in the project must completely enclose space so that InstalSystem 5 can correctly recognize it as Room.
  

Export Slab (IfcSlab)

• Slab should be uniform and simplified - try to avoid dividing Slab into several for each Room. The best is the creation of a single Slab for the entire Storey in the form of a rectangular parallelepiped;
• Avoid exporting Slab elements that are unnecessary for Thermal calculations of building (e.g., outdoor terrace, access road, load-bearing piles, foundation piles);
• Avoid multi-layer Slab - export the structural ceiling (without Covering, Insulation layer, etc.);
• Slab should be aligned with the outer contour of the external Wall;
• Avoid division of Slab on the Storey, e.g. into a ring beam and the Slab itself;
• Avoid Opening in slab elements if they are not used to connect Rooms between Storeys - avoid exporting excess Opening in slab unless it is used to connect Rooms between Storeys (e.g. stairwell openings);
• Opening in slab should not overlap Wall;
• The foundation Slab should not form a separate Storey on its own;
• Avoid geometrically inconsistent Slab panels with cut-outs, e.g. Recess;
• Flat Slab: no sloped Slab / Ramp if the slope is minimal (e.g. roofs or balcony slabs) - from a Thermal calculations of building perspective, such a slope is negligible. Such Slab should be simplified;
• Avoid export of the Stairs element - InstalSystem 5 does not contain the Stairs element in terms of Thermal calculations of building. It is modelled using an Opening in slab;
• Shifted Slabs within a Storey - if there are significant shifts in Slabs within a single Storey that are important from the point of view of Thermal calculations of building and the planned installation, they must be exported in accordance with the rules and recognized in the program through an additional or internal storey level. For more information, see: BIM - Creating additional and internal storey levels.
  Displacements of Slabs by several centimeters should be avoided, and such Slabs should be simplified.
  

Export Roof (IfcRoof)

• Roof must be uniform - export the Roof as a single element, not as several separate parts;
• Multiple Roof slopes - complicated roofs can be connected during the interpretation in InstalSystem 5 only when the thickness of the slopes is the same, the slopes are perfectly tangent to each other and there are no openings between them;
• Avoid Opening in Roofs - such elements are not recognized by InstalSysytem 5 as Roof window elements;
• Roof should not contain vertical Roof edges or should be exported as two separate elements - InstalSystem 5 does not support vertical Roof edges and such cases must be modelled as multiple Roof slopes;
• Exclude Dormer element - if there is a Dormer on the Roof, it should not be exported. Cover the opening with a single Roof section and create a native InstalSystem 5 Dormer element. The exception is when the Dormer is created by a uniform Roof shape that can be modelled as slopes without vertical Roof edges. For more information, see: Creation of dormers;
• Roof is not assigned to a separate Storey - assign roofs to the Storey containing the Slab and Walls that enclose the spaces to create Rooms (the "closed box" principle).

Articles, related to the Roof creation: Interpretation of roofs, Preparation of building structure - Roof modeling.

Export Window, Door, Opening in wall (IfcWindow, IfcDoor, ifcOpeningElement)

• Windows and doors must be fully embedded in the walls - the elements should belong to a single Storey, with no parts protruding beyond the Wall structure;
• Roof window must be fully embedded in a single Roof slope;
• Corner Window should be divided into two separate windows that are entirely contained within a single Wall;
• Curtain walls / large glazing (IfcCurtainWall) - treat as walls in accordance with the rules described for walls. InstalSystem 5 interprets IfcCurtainWall objects as Curtain Wall elements, which have the same characteristics as Wall elements.
  

Export Rooms (IfcSpace)

• The upper and lower boundaries of Room (IfcSpace) should be set correctly:
  • Upper boundary - Room is bounded at the top by the lower edge of the ceiling Slab,
  • Lower boundary - Room is bounded at the surface of the floor slab (without cladding, insulation layer, etc.). This will ensure the correct recognition of shape and volume of the Room;
• Ensure that the space within Rooms is correctly "trimmed" based on the floor slabs and ceilings. Otherwise, the program may not recognize the Room geometry properly, which will necessitate modifications directly in InstalSystem 5;
• Ensure that ifcSpace objects correspond to the logic of Storey creation in InstaSystem 5. For more information, see: Creating a storey;
• ifcSpace objects cannot overlap other ifcSpace objects or contain each other (e.g. functional, climatic or utility zones in a building);
• Avoid Rooms that are not inserted in the project - in Revit, it is possible that Rooms have been removed from the 3D view but still remain in the project. Delete any Rooms that are not inserted using Schedules to prevent unnecessary creation of additional IfcSpaces;
• Make the proper parameterization of ifcSpace elements (depending on the requirements) in order to automatically transfer parameters to Manual Rooms in the InstalSystem 5:

Parameter ifcSpace	Parameter InstalSystem 5
Name	Symbol
LongName	Description
TotalHeatLoss	Φreq,H - Required heating output
SpaceTemperatureWinterMin	θi,H - Design room temperature (Heating)
TotalHeatGain	Φreq,max,C - Required cooling output
SpaceTemperatureSummerMax	θi,C - Design room temperature (Cooling)
SpaceHumiditySummer	φi,C - Relative humidity

Concluding notes

• The accuracy of the geometry is crucial for correct thermal analysis - make sure that the elements are closed and simplified so that InstalSystem 5 can recognize Rooms;
• Checking IFC files - before importing into InstalSystem 5 review the exported IFC file in an BIM viewer to ensure that all elements comply with the above guidelines, including the correct assignment of elements to Storeys.

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