What is ifcOWL and what are its benefits in BIM

The ifcOWL translates the IFC data schema into the Web Ontology Language (OWL). Let’s see what is its structure and its characteristics

To make the BIM methodology operational and develop a process of programming, design, construction and maintenance of a construction through the creation of a digital twin, it is appropriate that all professional figures constantly collaborate with each other.

A standard format, a language common to all operators, is therefore needed to achieve interoperability. For this purpose, a new type of file format was created, allowing the secure exchange of information, the IFC (Industry Foundation Classes). This file format can also be viewed and modified through an online IFC viewer.

Did you know that an IFC file can be encoded in different formats?

In this article we will discuss one of them together: theifcOWL.

What is ifcOWL?

The ifcOWL provides a representation of the Industry Foundation Classes (IFC) data schema in the Web Ontology Language (OWL).

We know that the IFC, ISO 16739:2013 standard, is a structured data scheme; such data, aggregated according to a particular logic, gives rise to the information itself.

This standard maps, in an objective and non-interpretable way, all the possible and knowable entities connected to any process in the construction sector: objects, relationships and properties.

The schema is structured according to a descendant logic to which it is possible to determine a parent and child class and all are under a single IfcRoot entity class that is divided into:

1. IfcObjectDefinition;
2. IfcPropertyDefinition;
3. IfcRelationship.

IFC Data Schema Structure

The IFC format was created and developed starting from the EXPRESSlanguage, the structure of the file is STEP (Standard for the Exchange of Product model data), whose advantage, from an IT point of view, lies in the fact that:

• the information is recognized by different protocols;
• all data can be shared in a three-dimensional model.

Following the main IFC format, BuildingSMART introduced other formats, based on the encoding of the contained data and with the ifcOWL, it made the EXPRESS data scheme available in a large web ontology, in order to:

• support the semantic web application of data interoperability;
• ensure flexible data exchange;
• allow for distributed data management.

To fully understand the difference, let’s see an example: suppose you have a BIM information model and suppose you export it first to IFC and then to ifcOWL.

The ifcOWL file and the IFC file will contain exactly the same data. What changes between the two is the syntax, that is the way in which the data is described and stored. In regards to the ifcOWL, the syntax is linked to the web ontology.

What is a web ontology?

A web ontology, in computer science, is the representation used to describe the way in which different schemes are combined in a web data structure, defining all the specific entities present in the system and their relationships.

To define a web ontology it is necessary to use a language: OWL (Web Ontology Language) is precisely one of these, whose purpose is to formally describe the meaning of the terms used in web documents.

OWL is an extension of the Resource Description Framework (RDF), from which it differs. While RDF is a model to represent web resources through a defined syntax, OWL provides a vocabulary for the classes, properties, and relationships of RDF resources.

What is the potential of ifcOWL?

With the use of ifcOWL it is possible to represent the information of a construction through innovative web technologies, allowing to obtain a better management and exchange of data in the AEC (Architecture, Engineering & Construction) sector and beyond.

The OWL technology allows you to connect the IFC schema with other standards of other domains, linking the building data with:

• material data;
• manufacturer’s data;
• GIS data;
• cityGML data;
• classification schemes;
• social data;
• etc.

What are other IFC file formats?

In addition to the ifcOWL, the IFC also has other file formats, based on the encoding of the data itself:

• IFC-SPF: is the text format in the express data modeling language, where each row represents a single object. It has a “.ifc” extension and is the most used format because it has legible text with reduced size;
• IFC-XML: format used for interoperability with XML tools, with the extension “.ifcXLM“. Although XML is the most common programming language, this format is less used here due to its very large size compared to IFC-SPF;
• IFC-ZIP: is the zip compressed format of the embedded IFC-SPF file, with the extension “.ifcZIP“.

IFC file formats

If you want to learn more about the topic and how to quickly and easily create an IFC file, I invite you to read the article “How to create an IFC file“.

I also remind you that to open and edit IFC files in any encoding, you can use usBIM, the free IFC viewer online by ACCA software, to work on cloud and from any device.