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	2025-08-18

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 5.5 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 5.5

• 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;
• 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 5.5 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 5.5: each Storey contains such elements as Slab, Wall and Roof (on the top Storey).
  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;
• No multi-layer / adjacent Wall – export Wall as a single element (IfcWall), without separate structural layers,
• No Wall elements intersecting or overlapping each other;
• No Wall elements containing each other;
• No rhomboidal Wall elements – in 3D view, the wall should form a simple quadrangular prism with a rectangular base; the beginning and end of the Wall should form right angles with respect to the longer edge of the Wall;
• The Wall elements on the side view must be rectangular – an irregularly shaped Wall (when viewed from the side) will be recognized by the geometry defined by BoundingBox 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 BoundingBox 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 prism. After inserting the Roof and performing Calculations, InstalSystem 5.5 will cut the upper part of such Wall accordingly;
• No Wall elements cut out in the middle by modelling geometry if there are no Window, or Opening in wall there – InstalSystem 5.5 will fill such openings in accordance with the BoundingBox Length/Width/Height rule, assuming that there will be elements such as Window, or Opening in wall there;
• No L-shaped, U-shaped or similar Wall elements – each change in Wall direction as a separate ifcWall element;
• No export of ifcBeam and ifcColumn elements – if the absence of these elements does not affect thermal calculations, they should be excluded from export;
• No arched Wall – such Wall should be excluded from export and modelled in InstalSystem 5.5;
• Enclosed space – Wall elements in the project must completely enclose space so that InstalSystem 5.5 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);
• No multi-layer Slab – export the structural ceiling (without Covering, Insulation layer, etc.).
• Slab should be be aligned with the outer contour of the external Wall;
• No division of Slab on the Storey, e.g. into a ring beam and the Slab itself;
• No 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);
• No Opening in slab elements overlapping walls;
• The foundation Slab should not form a separate Storey on its own;
• No 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 ceilings should be simplified;