Benefits of BIM for the construction industry
The construction industry is growing rapidly but is facing problems with profitability due to the high impact of process and exchange errors caused by the fragmentation of the industry. Extensive digitization offers a solution to the construction sector through BIM technology. This involves digitally building the project in 3D form while integrating geometric and alphanumeric data. Some software uses advanced analysis of the model (clash detection, geometric and alphanumeric verification rules, graphic substitutions according to properties) which highlights in an automated way certain characteristics or problems in the BIM model, allowing the reduction of design errors and therefore errors and delays on site. In addition, the 3D model facilitates the understanding by the field workers of the elements to be executed.
In theory, the idea sounds good, but it often happens that, in the digital phase, some ambiguities arise in the flow of information between partners using this BIM technology.
Indeed, BIM models can be built in different ways, each engineering office, architecture office, or contractor uses BIM technology according to its own conventions. But when all these parties have to collaborate together on a BIM model, these different ways of modeling regularly cause problems. Models delivered by one party may not be used by the others because of different modeling conventions, so it is often faster to remodel from scratch. Moreover, some information is sometimes missing or stored in a different way (different name and/or different folder). In addition, there is the question of file formats, as each party does not necessarily work with the same software. For this last point, an open exchange format is available in most software and allows the exchange of 3D models with all the information, it is the IFC, Industry Foundation Classes), and it is both a standard (ISO norm) and a file format.
Despite the existence of this universal exchange format, it is not easy to correctly manage a model exchange via IFC. In addition to managing the information in the native model, there is also the IFC mapping with its set of rules to respect (Pset, Qto, class, predefined types, etc.). Each participant in a project must therefore invest a considerable amount of time to achieve these configurations, without necessarily achieving a perfectly satisfactory result. In addition to the complexity of implementation in software, modelers are confronted with different demands for each project. They have to reconfigure properties and IFC mappings for each project and repeat this tedious work.
A common reference to simplify life for all actors
It would therefore be desirable if everyone can rely on a common reference: the client for the definition of needs; designers, and companies for the implementation of the models and exchanges of models. Aware of the stakes in terms of information exchange in BIM projects in the BENELUX and in Europe, Buildwise (Belgium) and CRTI-B (Luxembourg) have decided to collaborate to establish together common exchange rules and to propose a standardized approach to information delivery, the whole based on the European standard EN 17412-1 – Level of Information Need. The BIMids platform is structured by the construction elements presented in the form of descriptive sheets describing the requirements to be provided. This approach simplifies consultation for professionals in the sector who are not particularly familiar with BIM standards or classifications.
- LOIN – Level of Information Need: The European standard EN17412-1 considers that to define the requirements of a BIM model, it is necessary to define:
- Who must provide the information: here, the actor or the discipline
- When information must be provided: we have chosen the project phases
- For what purpose the information must be provided: the BIM Use Case(s) concerned
- What information must be provided: EIR, i.e. geometry, information, and documentation requirements for each element of the model.
The Level of Information Need as defined by EN17412-1 is a concept that allows writing an EIR in a specific context regarding a discipline and a combination of BIM use cases.
- BIM use case: this is a specific objective that you want to achieve on the basis of the BIM model, for example, “cost evaluation” based on the extraction of quantities from the model. You can consult the list of Luxembourg use cases in Chapter 2.4 of the Luxembourg Application Guide.
- Project phases: this involves breaking down a project into phases in order to define at which phase information should be provided (note that the terminology differs slightly between countries):
- Preliminary design
- Final project / Authorization and approval file
- Final project / Execution file / Tender and award
- Work / As-Built
- Discipline: It is about defining the contributors (actors) to the elaboration of a model. In BIM level 2, each designer produces his own model, these models are then superimposed for technical coordination.
- Architectural model
- Structural model
- Technical model
Note that not every constructive element has to be modeled in each discipline: some objects are sometimes duplicated or move from one model to another depending on the phase. For example, a light fixture can be found in the architectural model only in phases 1 and 2 and in the technical model from phase 3 to phase 5. A wall is modeled as a single layer in phase 1 and with all its layers for phases 2 to 5 in the architectural mock-up, whereas the structural mock-up will only include the load-bearing layer from phase 1 to 5…
- GID – Geometry, Information, Documentation: this involves breaking down the requirements for a constructive element in the model according to 3 criteria:
- Geometric representation of the object in the model (single layer, multi-layer, specific profile added or recessed….)
- Properties associated with the object in the model (fire resistance: REI60, load-bearing: true/false, etc.)
- Documentation: related to the object such as datasheet, maintenance manual, calculation manual, and technical details … This documentation is not integrated into the BIM model but url links integrated into the objects of the model can refer to these documents, which must, in this case, be hosted online (on a document manager).
- EIR – Exchange information Requirements: the information requirements for model exchange define for each construction element what information must be provided at the GID (Geometry, Information, Documentation) level for each phase of a project.
It is important to note that the requirements included in the BIMids platform are the “minimum requirements”, i.e. the production of architectural, structural, and special technical models as well as the coordination between models. Additional use cases will be added in the near future, and it will be possible to consult and download the requirements with a combination of specific use cases in addition to the “minimum requirements”.
The platform provides you with files by construction element (GID file) in the form of a web browser to consult the geometry, information, and documentation needs of the current construction elements. It is possible to filter by native software and discipline. You also have the possibility to comment and post questions and suggestions for the whole content. An XLSX file containing the content of these pages is also available for download.
These sheets are organized by a grouping of similar elements (e.g. the window sheet includes the elements window but also the roof window, skylight, cupola, and smoke vent). They also follow the IFC structure. We support the OpenBIM approach to avoid the oligopolies of software editors and to allow everyone to work on the software of their choice, as long as it is OpenBIM certified. In this perspective, the exchange of models should generally be done in the IFC format. The correspondence (mapping) of each property and element of the construction is therefore also available.
However, the sheets are also applicable to the native models since it is a question of which tools and parameters should be used in the native software. How the native model is structured is however not in scope and there are other standards for this (e.g. BERSnl).
IDS: configuration files
The BIMids platform provides the user with configuration files to further assist with interoperability, the downloadable packages include:
- IDSconfiguration: Configuration files for different modeling software in order to implement the required properties per object category at each phase of the project (Revit, Archicad, Allplan…), as well as to integrate the most used classifications in Belux.
- IDSmapping: Configuration files with all the parameters for the IFC export, taking into account the properties created in the modeling software.
- IDSchecking: verification rule files for checking the model after IFC export in IFC model analysis tools (Solibri, SimpleBIM, to come)
The “software guides” are intended to assist modelers in the data management process, from the integration of the modeling software to the generation and control of the IFC. This guide describes the different steps following the predefined workflow in the “automatic” version. Eventually, this guide will include a “modeling” section that will specify the best practices for modeling by OBJECT as well as the way to proceed for each property.
Organisation des ressources :
- In the tab software generalities, you will find the settings to make in your software, the possible plugins to install and the configuration files to download.
- In the tab “Select an object” which will send you to the BIMIDS portal, you will be able to browse through the building elements and find for the desired object the GID sheet with the Geometry, Information and Documentation requirements as well as the mappings to the IFC classes and types and to the Uniformat II 2010 and DIN 276 classifications. The search on objects works with synonyms: you can type either the name of the construction element, or an IFC class or a predefined IFC type: a preselection of records including the term will be displayed and you can click on the desired record. Note that the breakdown of objects in the records follows the IFC classification and depends on the information requirements. On the other hand, two objects of the same IFC class but of different types will be in the same record as long as the information requirements are identical. Examples :
- Insulated and threaded footings are included in the same file since they are the same IFC class (IfcFooting) and the information requirements are identical. The only difference is the predefined type (PAD-FOOTING or STRIP_FOOTING) but this does not justify duplicating the record.
- The technical floor is not included in the same sheet as the floor finishes, even though the class and IFC type are identical (IfcCovering type FLOORING). Indeed, additional information requirements are required for the technical floor compared to a floor covering.
The features will be implemented progressively in the configuration files. Here is a summary of the features currently available:
|Functionalities (Revit – Archicad)||Implemented from version x|
|1.a. Implementation of the properties||yes (v1.2)|
|1.b. Liste de valeurs prédéfinies||yes (v1.4)|
|1.c. Description de chaque propriété||yes (v1.3)|
|1.d. Link to BIM portal page|
Online help by object on BIM portal
|2. Configuration mapping IFC 2X3 and IFC 4||yes (v1.2)|
|3. Control of the generated IFC file||Coming in 2023|
|4. Separate layer management||no|