Building information modelling (BIM)

Building Information Modelling (BIM) refers to the optimized design and construction of buildings by means of suitable software. BIM is a smart digital building model allowing all the partners involved in a project - from architects and builders to building services and facility managers - to work together on and jointly implement this integrated model.

1. Background

At the outset of a construction project, the architectural design is drawn up based on the requests of the client. Building thereon, CAD systems are used to prepare the technical design and construction drawings required for execution and, subsequently, to determine the necessary construction works, measurements and costs.

If plans are modified, the technical construction drawings and calculations have to be updated - for example, with regard to structural engineering or building services. In traditional construction planning, such adjustments result in major additional work and coordination efforts, which can be significantly reduced by building information modelling (BIM).

In the case of BIM, the architect or specialized engineer input modifications in the project file - the model. This method allows them to analyze changes and perform new calculations immediately and promptly evaluate key parameters such as space requirements and structure heights.

As a result, changes are directly available to all the partners involved - both in the form of drawings and data packages. If, for example, the ground plan changes, this may impact the installation of doors and windows. If the person in charge modifies the descriptions in the digital data model, unit lists and calculations are automatically updated.

2. Intelligent digital building model

BIM is used to draw up an intelligent digital building model that can be examined and edited collaboratively by all the partners involved. The model is based on the industry standard Drawing Interchange File Format (DXF) that is in the public domain and fully supported by the software industry.

The format used in ÖNORM A 6240-1 defines commands for storing grouped information. This aspect is used in an innovative way by the standard by defining how to file graphic data in a structured way and how to exchange intelligent building data and information. Austrian Standards makes available a free file conforming with the standard (in German) to all users for preparing the data model. 

The data model digitally specifies all the relevant building data and combines and links them. The building is also geometrically represented as a virtual computer model. The BIM data are of a very high quality as they are drawn from a common data basis and are continually updated and synchronized. The immediate and continuous availability of all the current, relevant data ensures optimal information exchange between the partners and helps improve the efficiency of the planning process with regard to cost, deadlines and quality.

3. Software solutions

The software industry offers numerous solutions for architecture and construction planning. The best-known packages are AutoCAD Architecture and Revit by Autodesk, archiCAD by Graphisoft, allplan by Nemetschek, speedikon Architectural by Bentley Systems and arcad by the company of the same name.

The companies involved in the development of ÖNORM A 6241-1 and ÖNORM A 6241-2 offer different solutions for BIM. AutoCAD has an add-in for the necessary country-specific requirements. Together with the interfaces needed, BIM is already integrated in the latest version of ArchiCAD. Austrian Standards offers all users a free file conforming with the standard (in German) for creating the data model.

4. New series of standards on digital modelling

The standards on digital modelling will be grouped in the new standards series ÖNORM A 6241. ÖNORM A 6241-1 is considered the successor document of ÖNORM A 6240-4 that was expanded to include execution and detailed plans and to eliminate ambiguities. ÖNORM A 6241-2 defines all requirements for Level 3 iBIM.

ÖNORM A 6241-1 "Digital structure documentation - Part 1: CAD data structures and building information modelling (BIM) - Level 2"

Scope: This standard applies to the technical implementation of data exchange and the storage of building information, including alphanumeric data contained in building models that are required during planning and the life-cycle management of buildings and related spatial civil engineering structures.

It lays down the most important terms and definitions, structures and presentation principles for fundamental methods used for transferring data held in two-dimensional CAD files and for building information modelling (BIM).

ÖNORM A 6241-2 "ÖNORM A 6241-2 Digital structure documentation - Part 2: Building Information modelling (BIM) - Level 3 iBIM"

Scope: This standard governs the technical implementation of a multidimensional, structured standard data model for buildings and related civil engineering structures based on Level 3 building information modelling (BIM).

Moreover, it lays the foundation for the comprehensive, standardized, product-neutral, systematized exchange of graphic data and related object data based on IFC (Industriy Foundation Classes) and bSDD (buildingSmartDataDictionary).

5. Organizational aspects

At Austrian Standards, the subject of building information modelling is assigned to Working Group 011.09 of Committee 011 "Building construction" chaired by Arch. Dipl.-Ing. Peter Kompolschek and managed by Dipl.-Ing. Stefan Wagmeister.

As there are no standards in effect at the international and European level at present, a European committee (CEN/TC) was set up to develop them.

Austrian Standards nominated Arch. Dipl.-Ing. Peter Kompolschek and Ing. Peter Muigg to represent Austria in the European committee.

Author: Herbert Hirner

6. Bibliography

ÖNORM A 6241-1 Digital structure documentation - Part 1: CAD data structures and building information modelling (BIM) - Level 2
ÖNORM A 6241-2 Digital structure documentation - Part 2: Building Information modelling (BIM) - Level 3 iBIM

Information on the BIM Summit Austria