What is IFC Format? Exploring BIM and IFC Models in Detail

What is the IFC format and why is it important?

The Industry Foundation Classes format is the cornerstone of modern building information modeling. It is an open file format that has completely changed the way building data is stored, shared, and utilized, providing a sophisticated yet interoperable approach to digital construction documentation.

Unlike most BIM solutions with their own proprietary file formats, IFC acts as a universal language of sorts for construction data, transcending the borders of individual platforms and encouraging collaboration between disciplines. As we take a closer look into the IFC format, we will see how it has become the backbone of integrated design and construction processes in a modern-day built environment that is growing more and more digital as time goes on.

What does an IFC file entail?

An IFC file is a comprehensive digital container for building information that can hold far more than just geometric data. Its core file structure consists of a schema-based data model describing physical and functional information about building elements. These files have a unified .IFC extension and contain structured information about windows, doors, walls, HVAC systems, and virtually every other building component, including all their relationships, properties, and even spatial context.

This semantic richness is what sets IFC files apart from regular 3D models. Instead of merely representing the shapes of objects, IFC includes the understanding that each element of a building (such as a wall, a door, a window, etc.) is an actual object with a fire rating, material specifications, thermal properties, and connections to other building elements. Such intelligent objects allow stakeholders to use the model as a centralized source of specific building information, making complex analyses in different fields a lot more convenient.

IFC also supports multiple representations of the same building information, such as detailed geometric descriptions or abstract spatial relationships. This makes it adaptable to different stages in the design and construction process. IFC can accommodate vastly different levels of development within a single file format, from conceptual mass models for architects to precise assembly details for contractors.

Why is the IFC model essential for BIM?

The building information modeling methodology relies a lot on the seamless exchange of building information, which can be challenging without unified formats such as IFC. As the only internationally recognized open standard in the BIM ecosystem, IFC can help with genuine collaboration across different software platforms and disciplines that may otherwise remain isolated in their own proprietary data silos.

The essence of BIM, its primary goal, is to create a single source of truth for all project information. This vision would be a lot more difficult to achieve without IFC, considering how design teams tend to rely on specific software tools that differ from each other. IFC can help architects, engineers, contractors, and other stakeholders to work with the same building model regardless of their preferred software environment by providing a neutral, non-proprietary data format.

Additionally, many governments and clients worldwide have already mandated IFC compatibility in their BIM requirements, reinforcing its role in achieving transparency and long-term data accessibility of building information. Such widespread standardization has elevated IFC from a technical solution to a strategic business necessity for businesses that work in the architecture, engineering, and construction industry.

What is the role of IFC in the lifecycle management of buildings?

The IFC format has the power to serve as a digital thread of sorts that connects each phase of the life cycle throughout a building’s entire existence from conceptualization to demolition. At the early design stages, IFC can help facilitate rapid iteration and multi-disciplinary coordination, with the same model evolving into detailed assemblies as projects progress to construction.

At the same time, the true value of IFC becomes even more obvious after the construction process is complete. Facility managers can use BIM models after construction as rich, structured datasets capable of documenting every single element of a built structure, with all the maintenance schedules, equipment specifications, and warranty information. This is called the digital handover process, and it dramatically improves operational efficiency when compared with traditional paper documentation, offering massive potential savings throughout the building’s entire lifecycle.

Outside of daily operations, IFC can also help support strategic decision-making when it comes to space utilization, energy retrofits, renovations, and so on. The ability to start each major modification process with accurate as-built information at hand is a lot more convenient than having to survey the existing conditions of a building from scratch. This information continuity might be one of the most substantial advantages of IFC: the ability to preserve building knowledge across large time periods, reducing the traditional gaps between design, construction, and operation.

How does the IFC model facilitate interoperability?

Collaboration is the most fundamental element of modern construction projects, with a variety of specialists working together across different disciplines. IFC can serve as a digital bridge that connects different areas of expertise together. Interoperability is the cornerstone of the existence and continued development of IFC, transcending the limitations of proprietary data formats to enable seamless information exchange. A foundation of shared understanding affects everything from quantity takeoffs to clash detection, creating a unified digital environment where different teams are free to collaborate in an effective manner even when they use different software tools.

What is interoperability in BIM and IFC?

Interoperability in the context of BIM is the frictionless exchange of building information between different software solutions with no loss of intelligence or meaning. Unlike basic file conversion processes, true interoperability can preserve the semantic richness of the original data, ensuring that objects remain objects instead of turning into collections of lines and surfaces.

IFC achieves interoperability through a standardized object-based data model that provides a common language for describing building elements. This approach helps software applications with mapping native objects and properties to corresponding IFC entities during export or in reconstructing equivalent native objects during import. The format itself can capture not just what an object looks like but also what it is and how it relates to other objects in a structure.

This semantic interoperability extends far beyond geometric boundaries to encompass material properties, construction sequencing, performance requirements, and many other aspects of a building information model. When implemented properly, it helps specialists work in their preferred environments while still maintaining meaningful connections with the broader project ecosystem.

How do different software applications use the IFC model?

Architectural design platforms such as ArchiCAD, Revit, and Vectorworks use IFC to export comprehensive building models that preserve the design intent and element relationships in the model. The ability to choose which building elements and properties are included in the export is usually included in the package, helping users tailor IFC models to specific exchange requirements.

Engineering software such as Robot Structural Analysis or Tekla Structures can import IFC models as reference data and then export their own specialized models (structural or mechanical, electrical, and plumbing models) back to the project teams. Such cyclical exchange helps create a continuous coordination loop between disciplines as the design evolves.

Construction management tools like Solibri Model Checker and Navisworks can use IFC to aggregate models from several sources, helping identify clashes and other issues before the field stage of the construction process. Such applications rely heavily on the ability of IFC models to maintain consistent object identifiers across revisions to allow for automated tracking of changes and resolutions.

Facility management systems like IBM TRIRIGA or ArchiFM can import as-built IFC models to serve as the foundation for operational databases, extracting equipment information, space data, and maintenance requirements directly from the construction documentation. This seamless transition from construction to operations is one of the most valuable yet underutilized aspects of IFC workflows.

What are the benefits of using open standards in data exchange?

The open-ended nature of the IFC standard offers substantial advantages compared with many proprietary alternatives.

• The elimination of vendor lock-in helps IFC empower building owners and project teams to select the best tools for specific tasks instead of compromising capability for compatibility. This fosters innovation and competition among software vendors and even reduces overall project risk.
• Long-term data accessibility is another advantage of the open IFC standard, addressing a critical concern in an industry where the result of the average project may survive for decades or even centuries. Proprietary formats can always become obsolete when companies cease operations or change direction, but the open-ended nature of IFC will remain accessible at any time regardless of market developments.
• The transparent development process of IFC, spearheaded by buildingSMART International, results in a standard that is developed according to expert consensus instead of corporate interests. This collaborative approach helps IFC address real-world needs across different disciplines and regions with ease.
• The democratization of access to BIM is also a massive advantage of IFC, and some might even say it is the biggest advantage by far. This approach fosters the widespread adoption of efficient, data-driven practices, making it possible for businesses of all sizes to participate in the digital construction ecosystem.

What is the importance of IFC certification for software tools?

IFС certification is quality assurance for building professionals navigating a complex software landscape. An official certification from buildingSMART International is a demonstration of verified compliance with specific IFC import and export capabilities in accordance with standardized test cases and exchange requirements.

This certification can help businesses make informed procurement decisions with the confidence that certified applications can actually deliver on the promised interoperability. Instead of relying on marketing claims or the results of limited in-house testing, teams can easily reference objective third-party validation of compatibility.

The certification process is also a part of a positive feedback loop in the industry itself. Software vendors acquire detailed technical feedback during certification testing, which helps them improve their implementation of IFC standards. As more applications become certified with IFC and more projects demand it as a requirement, the overall quality of IFC implementation becomes higher on average throughout the entire industry.

IFC certification is a non-negotiable prerequisite for complex projects involving international teams or clients from the public sector. Many government-level BIM mandates explicitly require the use of certified software to guarantee data exchange and archival capabilities on a certain level. This is one of many ways to reinforce the importance of certification in maintaining consistent standards across the global construction industry.

What are the key components of the IFC schema?

Behind the practical applications of IFC is a complex technical framework that makes information exchange possible to begin with. The IFC schema is a comprehensive data model that precisely defines how building information is categorized, structured, and interconnected within the format. Professionals in the construction field have to understand how IFC works in order to leverage its full potential while avoiding common pitfalls in data exchange and implementation.

How is IFC data structured?

The structure of IFC data follows an object-oriented paradigm in which building elements and concepts are treated as entities with their own distinct properties, identities, and relationships. It mirrors the physical reality of construction, with discrete components combining in complex systems and assemblies. The IFC schema organizes these entities in a hierarchical manner, with more specific types of element able to inherit the characteristics of general parent classes.

It is the inheritance principle that forms the backbone of IFC’s flexibility. For example, all physical elements in a building are inherited from IfcElement, which provides common attributes such as spatial placement, containment relationships, etc. There are also more specialized classes like IfcWall or IfcWindow which extend the abovementioned foundation with additional properties that are specific to their function. This logical structure helps software process building elements at appropriate levels of abstraction depending on the current task.

The spatial organization within IFC helps create a nested containment hierarchy to reflect how buildings are arranged physically. This starts with IfcProject at the highest level of the hierarchy, descending through sites, buildings, stories, and spaces to establish context for all the building elements contained. This enables powerful spatial queries and analyses such as finding all the elements on a specific floor or in a specific room, regardless of their system classification or discipline.

What types of information are included in the IFC format?

Physical and geometric information is the most visible aspect of the IFC format. It encompasses the shape, size, location, and orientation of any building element. IFC can work with multiple types of representation, from simple bounding boxes to detailed boundary representations, providing models with the proper adaptability for different levels of detail throughout the project’s lifecycle. This geometric flexibility makes it possible for IFC files to help with both detailed construction coordination and conceptual design reviews.

Material and performance data is another important layer of IFC information that can give meaning to physical elements. For example, mechanical equipment can carry electrical requirements, efficiency metrics, and capacity ratings, while wall assemblies store thermal properties, acoustic performance, fire ratings, layer compositions, etc. Non-geometric information like this can transform simple 3D models into complex digital twins with extensive analytical capabilities.

Relationships and connections between elements are just as important in the context of IFC data models. IFC explicitly defines how elements are related to each other rather than leaving it to the software to infer these connections based on geometry alone. This includes:

• Logical groupings, such as elements belonging to particular systems or assemblies.
• Functional relationships, such as equipment serving specific zones.
• Physical connections, such as walls hosting windows.

Project management information is the last large information category of IFC. It incorporates cost information, resource assignments, procurement details, schedule data, and more. It is a temporal and financial dimension (4D and 5D BIM, respectively) that allows IFC models to support both the construction sequencing and cost analysis capabilities of building information modeling environments. IFC bridges the gap between design documentation and project management systems by connecting physical elements with project delivery information.

How does the IFC specification ensure data integrity?

The IFC specification uses rigorous data validation mechanisms to maintain consistency throughout complex building models. At the most basic level, the schema is used to define strict data types and constraints for each attribute in order to prevent the storage of incompatible or illogical values. More complex rules also enforce entity relationships, making sure that the connections between elements remain operational and that any required dependencies remain satisfied. Validation rules like these help create a strong foundation for reliable data exchange processes.

In addition to individual attributes and relationships, IFC also uses global uniqueness requirements and reference integrity checks to preserve the coherent nature of the entire model. Each entity has a distinct identifier that stays consistent across different software platforms, helping with element tracking throughout different stages of the project lifecycle. Referenced entities also must exist within the model in order to prevent dangling connections with the potential of compromising data integrity. The combination of all these mechanisms ensures that IFC models can remain internally consistent across different software environments.

What are the different types of IFC entities and how are they used?

IFC entities fall into a number of distinct categories that form a comprehensive representation of a building project. Some of the most common examples are:

• Physical elements – tangible components that make up the built environment.
• Spatial elements – define the overall organizational structure of the entire project.
• Relationship entities – capture connections between other entities in the form of a logical structure.
• Domain-specific entities – cover specialized needs of different disciplines in the industry.
• Structural entities – load-bearing elements, connections, and analytical representations necessary for engineering analysis.
• MEP entities – system relationships, performance criteria, and connection points needed to coordinate building services.
• Architecture-focused entities – spatial requirements, accessibility concerns, and design development information.

This is where we should also mention the topics of shared entities and property sets. They provide standardized ways to enrich basic elements with additional information without the need to define discipline-specific attributes directly on element entities. What IFC does instead is use property sets (collections of related properties) that can be attached to various types of element. This allows the schema to remain manageable while supporting highly detailed discipline-specific information. It is possible to create project-specific property sets for custom project requirements, and there are also several common property sets that are predefined in the IFC specification, as well.

Additionally, the IFC schema can use abstract support entities, facilitating more complex data modeling. For example, there may be geometric representation items, material definitions, approval and actor entities, etc. These entity categories help reinforce the overall infrastructure that enables the schema to represent both the physical building and the entire collaborative process it relies on.

How do you work with IFC files in BIM projects?

The appropriate tools and methodical processes are both necessary to be able to use IFC files properly. The technical complexity of IFC offers a variety of advantages, but it also necessitates a very careful approach to maximize interoperability without creating a myriad of potential issues. On the other hand, businesses that develop clear IFC workflows and equip their teams with the correct resources can massively improve their project efficiency across the board.

What tools are available for handling IFC files?

Major BIM authoring platforms create the foundation for professional IFC workflows, each with its own approach to implementation. Autodesk Revit has robust IFC export capabilities with its open-source IFC exporter, which allows users to fine-tune how native elements map to IFC entities. Graphisoft ArchiCAD has a native IFC database that can maintain a parallel representation alongside proprietary data, resulting in particularly clean exports. Many other platforms also have their own quirks and specifics when it comes to IFC implementation, often with their strengths aligned to their primary disciplines.

If a stakeholder does not have access to full BIM authoring tools, there is also a diverse ecosystem of specialized IFC viewers that offer the essential capabilities for access to model information. There are many options to choose from, both free and paid, with all these applications serving as critical communication bridges between technical and non-technical team members in order to democratize access to building information for the entire project team.

Advanced validation and analysis tools also help in their own way, addressing the need for quality assurance in IFC workflows. Revizto is a good example of such a tool, offering powerful model checking capabilities for clash detection and issue tracking. The exact specifics of this tool are covered below.

How does Revizto facilitate IFC-based collaboration in BIM projects?

Revizto can leverage the rich information contained in IFC files to create an integrated collaboration environment that transcends the traditional boundaries between disciplines. The platform can import IFC models from multiple sources, preserving their overall semantic structure while also creating a unified 3D environment for all stakeholders to work in. This allows architects, engineers, contractors, and clients to interact with consistent building information regardless of which tool was used to create the original models.

The issue-tracking and communication features of the platform build upon the foundation of IFC to create a structured coordination workflow. Teams can easily identify clashes between models, assign responsibilities, track resolutions, and document decisions in the context of the integrated model. All this coordination activity remains connected to the specific building elements it affects  thanks to existing links to the underlying IFC data. This creates a transparent record of project development, increasing accountability and reducing miscommunication.

How to ensure compliance with the IFC standard in construction projects

Being able to establish clear IFC requirements early in the project helps create a foundation for successful implementation. When a BIM execution plan is created, it should explicitly define which version of IFC is to be used, what model view definitions are required, and what level of detail is expected at each phase. All these specifications should be contractually binding, aligning with the project’s broader BIM goals to ensure that all parties understand their responsibilities.

Technical validation processes can be implemented at key points of exchange, verifying compliance with established requirements. Automated model checking validates IFC files against predefined rules, including completeness of information, project-specific requirements, and structural integrity. These validation checkpoints should occur before models are distributed to the broader team in order to prevent the propagation of problematic files down the line.

Team training and standardized procedures are also mandatory in a comprehensive compliance strategy. Even with advanced tools, high-quality IFC exchanges are greatly dependent on consistent practices and user knowledge. Standardized export templates and documented workflows can reduce variation between team members, while regular quality reviews can help the team refine its approach throughout the project’s lifecycle.

What are the best practices for troubleshooting export and import issues in IFC files?

Export-related challenges often arise because of improper configuration or model preparation. Standardized export templates can eliminate guesswork and inconsistencies in most cases. Cleaning procedures to remove unneeded elements and repair geometry issues should be performed before exporting. Breaking a larger model into logical segments before exporting is also an option to improve the manageability of the process.

Import difficulties tend to arise from compatibility issues between software implementations. When encountering import issues, verifying that all software is up-to-date is the first logical step. Adjusting the import settings to match the characteristics of the source model can also resolve a number of issues, especially in terms of categorization, unit conversions, etc. Recurring exchange partnerships can even establish collaborative testing processes for sample models early in the project to address any compatibility issues immediately.

If problems persist, it is highly recommended to follow a systematic approach with diagnostic workflows. It should be possible to isolate problematic elements from the get-go by conducting test exports with limited scope. In some cases, the use of an intermediary translation using a bridge application with strong IFC support may help resolve compatibility issues. Documenting successful resolutions is always a strong recommendation, creating a valuable knowledge base for future projects so that issues may be resolved in a proactive manner.

What are the challenges of using IFC files?

Despite their long list of benefits, IFC models also have distinct challenges that users must navigate for successful implementation. The format itself is highly complex, which is essential for its functionality, but which also tends to create technical hurdles, performance limitations, and workflow disruptions. Effective mitigation strategies can only be developed with a proper understanding of all these challenges.

What common issues arise when working with IFC models?

Geometric translation issues are some of the most frequent problems when it comes to exchanging IFC files between software environments. Advanced geometric representations, parametric components, and complex curved surfaces tend to lose fidelity or transform unexpectedly during translation. This geometric degradation often manifests as simplified shapes, missing elements, or misaligned components, compromising the visual appearance and the analytical accuracy of the model.

Semantic data loss is an equally significant issue during exchanges, even if it is less visible in comparison. Certain properties may map incorrectly in IFC format or disappear entirely during export. Additionally, classification systems and naming conventions tend to suffer during translation as well, complicating downstream organization and filtering tasks.

All these gaps in information undermine the overall usefulness of a model, especially for quantity takeoffs, analysis, and facility management, forcing team members to manually reconstitute critical information.

How does IFC file fragmentation impact data accuracy and consistency?

Project fragmentation happens when different aspects of a building have to be modeled separately due to the structure of the team or software limitations, which results in multiple IFC files that must be coordinated and used as one. Fragmented models like these tend to introduce a lot of coordination challenges, since changes in one fragment may not be reflected properly across the entire dataset. Each one of these disconnections leads to version conflicts and incorrect decision-making based on outdated information if not handled properly.

Additionally, current IFC implementations still suffer from underdeveloped cross-file relationship mechanisms, forcing teams to develop their own workflows and naming conventions. There are also many other more specific technical limitations that require careful oversight and rigorous coordination in order to avoid various issues with IFC models:

• Changes to element identifiers during updates break previously established relationships.
• Spatial containment and object positioning become inconsistent across fragments when reference points drift during separate editing sessions.

How can file size and complexity impact workflow?

IFC files have a tendency to grow a lot bigger than their native counterparts, expanding to 5-10 times the original file size in some cases due to the complex nature of the IFC data structure and other factors. Such large files strain network infrastructure during transfers and extend loading times, especially for team members with limited hardware power. The performance impact of large IFC files is most pronounced in larger projects, forming practical barriers to collaboration despite the original idea of the format as a collaborative assistant.

It is also not uncommon for the processing demands of parsing and rendering complex IFC models to exceed the capabilities of standard workstations, disrupting standard workflows in different ways, with laggy selection operations, slow and “jerky” visualization, and even issues with basic navigation operations. The technical burden of the complexity of IFC may thus widen the digital divide between office and field teams and may even undermine adoption among key project participants.

What strategies can be used to reduce the complexity of large IFC models?

Model segmentation is the most straightforward approach to managing the complexity of IFC, dividing large projects into more manageable components based on disciplines, floors, or building sections. Instead of working with large files that contain the entire project, teams can create purpose-built exports for their specific coordination needs, reducing file sizes and focusing attention on the relevant information.

Level of detail management is another strong methodology for controlling complexity. This involves carefully defining the appropriate levels of detail for different exchange scenarios. This way, teams can eliminate unnecessary information which does not add value. Early design coordination rarely requires fully detailed mechanical components or precise millwork details, whereas construction verification processes absolutely must include this information.

As such, the progressive development of detail aligned with project phases helps teams ensure that models contain sufficient information for their current tasks without introducing the burden of future requirements early on. This disciplined approach helps keep IFC models focused and lean throughout the entire project lifecycle.

Frequently asked questions

How do I open an IFC file if I don’t have BIM software?

There is an entire market of free IFC viewers that can be obtained and used without any experience with BIM software. BIMvision, Solibri Anywhere, and BIM Track are just a few examples of solutions that offer basic navigation and information extraction capabilities with no paid investment into specialized software.

Is the IFC format compatible with all versions of BIM software?

The majority of mainstream BIM solutions support both the import and export of IFC files, even if quality and consistency vary a lot from one application to another. It is not uncommon for IFC compatibility to improve with newer version updates, although there are also examples on the market that have left their integration capabilities as-is and have no plans to improve them in the near future.

What is the difference between IFC and other open formats like COBie?

IFC is a comprehensive representation of the entire building model with all the geometry, properties, and relationships. COBie is a standardized subset of IFC data that can be extracted and formatted as a spreadsheet, which makes it more accessible to facility managers but less than useful to the typical users of full-fledged BIM models.