Following on from my article about what is BIM and who does it impact, I decided to delve into another important BIM related subject. When the word BIM (Building Information Modelling) is used, IFC (Industry Foundation Classes) follows shortly after, but what is IFC and should you IFC, or not?
IFC stands for Industry Foundation Classes and is a data model which describes real building and construction industry objects like stairs, pipes, doors, windows, curtain walls etc. in a way that it can be represented in a 3D digital model.
It is an open file format, not controlled by one single vendor or group, and used by industry professionals to share data regardless of the software platform they use. Data from one phase of the building life cycle can be utilized in a later stage, without having to re-enter the data.
IFC is part of what is referred to as Open BIM and GraphiSoft describes it as ‘a universal approach to the collaborative design, realization, and operation of buildings based on open standards and workflows. OPEN BIM is an initiative of several leading software vendors using the open buildingSMART Data Model.’
To find out more about Open BIM please watch this short video.
What are the benefits of using IFC?
There are many benefits to using IFC including:
• Speaking the same language. Communication is very important when it is comes to efficient collaboration. To collaborate well, it must be clear what is meant by terms such as a door. What is a door, what are its functions and what is the performance? When I say “door”, do we have the same understanding of what it is?
• Different perspectives and needs. In projects, each party has different perspectives and needs for the same data and different opinions on what needs to be included in the model. For example: an architect is modelling an aesthetic curtain wall, facade builders want to include where the anchors of the curtain wall are located.
• Data ownership and changes. For collaborative projects, it must be clear who is responsible for which data and what changes are permissible. When parties use their own specialized models, and use a reference model to collaborate, it needs to be clear whose model it is and who is responsible for which changes.
Are there other alternatives to IFC?
Revit is an alternative, and is software for architectural design and documentation, created for architects and building professionals. The tools that make up Revit are designed to support BIM workflows. Revit however is a closed format file, compared to IFC which is an open file format.
Using Revit
If building project parties are all using the same BIM software (for example Revit), then collaboration will be much easier and streamlined, and eliminates error prone exports and imports. There is no need to do additional work in Revit to extract properties out and into IFC correctly.
For this reason, Revit has been chosen quite a few times as the tool to be used by all BIM partners. This can also cause a lot of double up work for contractors, who need to create the model in Revit, and then recreate the same model in their own specialized software. It is important that each party can use their own specialized software to do specific calculations.
Revit can do a lot but calculations and creating all the specifics required for quotation and production, are not things it can do. Open BIM embraces this and by providing an open standard, any software party can create an export to IFC.
Changes are permissible and effortless in Revit, for example it’s possible to adjust dimensions of a window or door; while a linked IFC does not allow these changes (the IFC model is static per definition).
On the flip side, permissible and effortless changes can cause problems. For example, if an architect changes the dimension to a value which is not valid for that product type, he will not know or be warned of the problem. Eliminating these problems are important.
Revit does not clearly define data ownership and thus allowing a person to change a part of the model that they ‘should’ not change. For example, if there are structural issues, they need to be the responsibility of the structural engineer but if a façade builder is able to and fixes them, it is then not clear who is responsible for what part of the model.
What should be considered before deciding?
When looking at your BIM requirements and what solution best suits your needs, it’s important to take into consideration the principles for successful collaboration:
• information classification: ensure the solution clearly includes what each part means.
• system independence: it allows you freedom to use the software you want to.
• workflow transparency: clarifies and allows for transparent workflows.
• ownership of BIM data: clearly defines who is responsible for what data and what changes are permissible.
• reference model concept: allows you to use your own calculation software and share information with a reference model.
Should you IFC?
The answer to ‘to IFC or not to IFC’ is a simple one, ‘to IFC’. It not only gives you great benefits but also fulfills all five requirements for successful collaboration.
