Glossary

BIM – Building Information Modeling

BIM (Building Information Modeling) ist eine Arbeitsmethodik für das Bauwesen, bei der ein digitales, dreidimensionales Modell eines Gebäudes nicht nur Geometrie, sondern auch alle Bau- und Betriebs-Informationen strukturiert enthält — vom Wärmedurchgangskoeffizienten der Fassade bis zur Betriebsdauer der Lüftungsanlage.

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BIM example – photoreal architectural rendering derived from a 3D model

What is BIM?

BIM stands for Building Information Modeling. Unlike classic CAD, which mainly delivers geometric drawings, BIM is a working methodology: a digital 3D model of the building contains not only walls, slabs and openings as geometric shapes, but every component also carries semantic and technical information — what material, what thermal performance, which manufacturer, which maintenance interval.

The result is a “digital twin” of the building: a model that covers the entire lifecycle — from the first conceptual study through permit application, execution design and shell construction to facility management after handover. BIM thus unites architecture, structural engineering, building services, cost and scheduling into one shared digital source.

In Switzerland, BIM has been mandatory for new federal projects since 2021 (Swiss BIM strategy); the large cantons and municipalities follow suit for public mandates. The relevant standards are SIA 2051 (BIM-based working method) and SIA 1.10 (BIM application documentation). The international reference standard for data exchange is the open IFC format (ISO 16739).

BIM vs. CAD

Although BIM software is often seen as the successor to CAD, the two concepts are fundamentally different.

CAD (classic)

Geometric representation: lines, surfaces, volumes. A wall is a series of lines on a floor plan. Changes to plan and section have to be kept in sync manually. Exchange formats: DWG, DXF. Software: AutoCAD, Vectorworks, Rhinoceros.

BIM

Object-oriented model: a wall is a component with properties (thickness, material, U-value). Changing a component automatically updates plan, section, elevation and bill of quantities. Exchange format: IFC. Software: Revit, ArchiCAD, Allplan, Vectorworks Architect, Tekla Structures.

LOD levels: information depth of a BIM model

The Level of Development (LOD) describes how detailed and information-rich a BIM model is at a given project phase. Each SIA 102 phase typically corresponds to a specific LOD level.

  • 100
    Conceptual study — rough volume, building as blocks. Corresponds to SIA phase 1 (preliminary study).
  • 200
    Preliminary design — approximate geometry with construction system, rough room programmes. Corresponds to SIA phase 31.
  • 300
    Construction project & permit — exact geometry, precise materials, dimensioned openings. Basis for the permit application. SIA phases 32 and 33.
  • 400
    Execution design — fabrication details, connections, manufacturer-specific components. Basis for works contract and tender. SIA phases 41 and 51.
  • 500
    As-built model — model of the actually built state after handover. Basis for facility management, maintenance, future refurbishments. SIA phase 53.

BIM and 3D visualization

BIM and 3D visualization complement each other ideally, but remain two distinct disciplines. A BIM model primarily serves planning, coordination and operation of the building — components are precise, materials technically documented, but visual quality is secondary. A visualization model conversely serves external communication — maximum visual quality, simplified geometry, focus on lighting mood and atmosphere.

At ArchVisual, we frequently take an architect’s BIM model as the basis and convert it into our visualization setup. From the IFC or Revit file we get geometry, room layout and base material classes — we add photoreal textures, furniture, vegetation, staffage and lighting. The architect saves the duplicate modelling, our studio delivers the visual quality.

Pipeline details on our architectural visualization page. For interactive applications from the BIM model (walk-through, configurator), see our 360° virtual tour page.

BIM project architectural visualization – exterior view derived from 3D model of a Swiss construction project

Related terms in the glossary

CGI (Computer Generated Imagery)

Umbrella term for digitally generated imagery — often derived from a BIM model as a starting point.

Rendering

The compute step that produces a photoreal image from a BIM or 3D model.

Rendering vs. visualization

Difference between compute step and finished image — both components of the BIM-to-visualization chain.

All glossary entries

Back to the full overview of technical terms around 3D visualization.

Frequently asked questions

Everything important about process, data, quality and outcomes.

What does BIM stand for? +

BIM stands for <em>Building Information Modeling</em>. It is a working methodology in which a digital 3D model of the building contains not only geometry but also all construction and operation information &mdash; thermal transmittance, materials, useful life, maintenance schedule.

What is the difference between BIM and CAD? +

CAD is essentially geometric: lines, surfaces, volumes. BIM adds semantic information to the geometry (what is a wall, which materials, what thermal performance) and temporal information (when built, when maintained). A CAD file contains a drawing, a BIM model contains a digital twin of the building.

What is the IFC format? +

IFC (<em>Industry Foundation Classes</em>) is an open, standardised exchange format (ISO 16739) for BIM data. IFC allows a BIM model to be transferred between different software &mdash; Revit, ArchiCAD, Allplan &mdash; without loss of semantic information. In Switzerland, IFC 4 is the reference standard for public BIM exchanges.

What are LOD levels (Level of Development)? +

LOD levels describe the information depth of a BIM model: LOD 100 (basic geometric concept), LOD 200 (approximate geometry with construction system), LOD 300 (precise details, exact positions), LOD 400 (fabrication details), LOD 500 (as-built model). Each SIA phase corresponds to a specific LOD level.

Is BIM mandatory in Switzerland? +

BIM is not mandatory for all projects, but has been required by the Swiss federal government for new federal projects since 2021 (BIM strategy). Swiss SIA standards 2051 and 1.10 regulate BIM use. Most large cantons (Zurich, Bern, Geneva) now require BIM for public mandates above a certain size.

How does BIM combine with 3D visualization? +

A BIM model often serves as the basis for an architectural 3D visualization: we take the geometry and structure from the IFC or Revit file, then add photoreal materials, lighting, furniture and staffage to produce the final rendering. BIM provides the geometric precision, our studio provides the visual quality.

Visualization from your BIM model?

Send us your IFC or Revit file. You will receive a fixed-price offer within 24 hours for the photoreal visualization of your BIM project &mdash; from exterior rendering to 360° tour.

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