Open BIM: Transforming the Construction Industry

Four firms are working on the same project. The lead architect is ArchiCAD. The structural engineer uses Tekla Structures. The MEP engineer runs MagiCAD on top of Revit. The facilities manager’s asset system expects data in a spreadsheet format it can import.

In a closed BIM workflow, this project starts with software negotiation. Someone converts to someone else’s platform, or the whole team ststandardizesne vendor’s ecosystem, or the coordination happens in PDF exchanges and misses the intelligence entirely.

In an Open BIM workflow, all four firms export and receive models in IFC, the open, vendor-neutral format managed by buildingSMART International. The structural engineer doesn’t need ArchiCAD to review the architect’s model. The facilities manager receives COBie data that their system can import directly.

That is the core of Open BIM. Not a specific product. Not single software. A set of open standards that lets different tools communicate without forcing everyone onto the same platform.

This article explains what those standards are, how they work in practice, and the section of most introductory guides to skip, where they still fall short of their promise.

What Open BIM Actually Means

‘Open BIM’ is used in two related but distinct ways and confusing them leads to real misunderstandings about what it delivers.

The first meaning is a workflow approach: designing and delivering BIM projects using open, vendor-neutral data standards so that any compliant software can read, write, and exchange model data. This is the primary meaning and the one this article focuses on.

The second meaning is sometimes used to describe open-source BIM software, free tools like FreeCAD or BlenderBIM that anyone can use without licensing costs. This is a different concept. Open-source software may or may not support open standards. Proprietary software like Revit supports open standards like IFC. The two dimensions are independent.

Operationally, Open BIM means three things for a project team. First, that each discipline can use the software best suited to their work rather than being forced onto a single vendor platform. Second, that model data is exchanged in formats that preserve intelligence, not just geometry, but component properties, quantities, material specifications, and system relationships. Third, that the building’s digital data remains accessible and usable over the building’s full lifecycle, independent of which software vendor’s future decisions.

The lifecycle data point is particularly important. Proprietary formats are controlled by their vendors. If an architect specifies a project in a proprietary format that the vendor discontinues or changes, the data becomes inaccessible. Open formats managed by international standards of bodies are not subject to individual vendor decisions.

Open BIM vs Closed BIM

The comparison between open and closed BIM is often framed as open = good, closed = bad. That is not accurate. Both approaches have genuine strengths. Here is the comparison done fairly.

Many projects use both approaches simultaneously: a core team running Revit natively (closed BIM internally) while exchanging IFC with structural and MEP consultants on other platforms (open BIM at the project boundary). This hybrid approach is practical and common.

buildingSMART: Who Governs Open BIM

Open BIM standards do not maintain themselves. They are developed, maintained, and updated by buildingSMART International, the non-profit organization that serves as the governing body for Open BIM.

Origin and structure

buildingSMART was founded in 1994 as the International Alliance for Interoperability (IAI), established by a group of AEC firms, including Autodesk and several large architectural practices, who recognized that the industry needed common data exchange standards independent of any single vendor.

It was renamed buildingSMART International in 2005. It operates through national chapters in more than 25 countries, including the US, UK, Germany, Norway, Singapore, Australia, and Japan. Each chapter engages local industry and government to promote adoption and provide regional input into international standards of development.

What buildingSMART produces

buildingSMART maintains four primary technical standards: IFC (Industry Foundation Classes), the core geometric and property data exchange format; bSDD (buildingSMART Data Dictionary), a library of standardized property definitions that IFC elements can reference; BCF (BIM Collaboration Format), the open format for issue tracking and coordination communication; and IDS (Information Delivery Specification), a newer standard for defining exactly what information a project requires and validating that models contain it.

The organization also maintains the BIM Collaboration Format workflows and certification programs that allow software vendors to demonstrate compliance with buildingSMART standards.

IFC: The Foundation of Open BIM

Industry Foundation Classes (IFC) are the most important Open BIM standard. If you understand IFC, you understand the core of how Open BIM works.

What IFC is and how it works The schema that defines how buildings are described as data

IFC is a data schema that defines how building components, spaces, systems, and their relationships are represented as structured data. A wall in IFC is not just geometry, it is an IfcWall object with properties: material layers, fire rating, acoustic rating, load-bearing classification, connections to adjacent walls, floors, and openings, and a relationship to the storey and building it belongs to.

When a Revit model is exported to IFC, the software maps Revit objects to their IFC equivalents. A Revit wall becomes an IfcWall. A Revit door becomes an IfcDoor. The associated parameters, material, fire rating, width, height, manufacturer data, are mapped to IFC property sets. The resulting .ifc file can be opened in any IFC-compliant application.

IFC versions From IFC2x3 to IFC4.3

IFC has gone through several major versions. IFC2x3 (2006) is the most widely supported version and remains the most common format for file exchange, most BIM software implements IFC2x3 reliably, even in 2026. IFC4 (published 2013, confirmed as ISO 16739-1 in 2018) introduced significant improvements in geometry, property handling, and infrastructure support.

IFC4.3 is the current flagship version, confirmed as ISO 16739-1:2024. It extends IFC coverage to infrastructure projects, roads, rail, bridges, ports, and waterways, bringing Open BIM into civil infrastructure alongside buildings. Adoption of IFC4.3 in mainstream AEC software is growing but not yet universal; many projects still use IFC2x3 or IFC4 for compatibility reasons.

IFC file formats .ifc, .ifcXML, .ifcZIP

IFC data can be stored in three file formats. The STEP Physical File (.ifc) is a text-based format, it can be opened in a text editor and read as structured data. It is the most common format and is supported by virtually all BIM applications. The XML format (.ifcXML) represents the same data in XML syntax, making it easier to process with standard XML tools but producing larger file sizes. The ZIP format (.ifcZIP) is a compressed version of either of the above, reducing file size for transfer.

For most project workflows, .ifc is the right choice. It is compact, universally supported, and processable by coordination and quality assurance tools.

The Other Open BIM Standards

IFC handles geometry and physical properties. A complete Open BIM ecosystem requires additional standards for specific purposes.

Benefits of Open BIM in Practice

The real benefits of Open BIM are most visible at the friction points of multi-firm projects, the moments where different software environments collide. Here is what changes when those exchanges are governed by open standards.

Structural engineers use Tekla; architects use ArchiCAD; MEP uses Revit

On a project with three different BIM authoring tools, IFC exchange allows each firm to work in their best tool. The structural engineer produces IFC from Tekla, the architect imports it into ArchiCAD to verify structural coordination, and the MEP engineer loads all three IFC models into Navisworks for clash detection.

Without IFC, this project either forces everyone onto one platform; a significant business disruption, or coordination happens through exported DWGs and PDF overlays, losing all the model intelligence. With IFC, intelligence flows across platform boundaries.

Facility managers receive usable handover data

At project completion, the facilities management team needs to know what equipment is in the building, where it is, what maintenance schedule it requires, and where spare parts can be sourced. In a traditional handover, this information is in binders, PDFs, and CAD drawings that no one can query.

COBie handover packages extract this information from the BIM model in a structured spreadsheet format that facility management systems can import directly. Spaces, assets, systems, job plans, and warranties are all structured and linked. The facilities team starts operations with queryable data, not a filing cabinet.

Issue tracking across software platforms

BCF-based issue management allows clash detection results from Navisworks to be communicated to ArchiCAD, Revit, and Tekla users simultaneously. An ArchiCAD architect can see the exact viewpoint of a structural clash, assign the resolution to the structural engineer, and track the response, without needing Navisworks.

This replaces the screenshot-in-email coordination workflow that most multi-firm projects still use. Issues are linked to model locations, assigned to responsible parties, tracked to resolution, and logged for contractual purposes.

The Honest Section: Where Open BIM Gets Complicated

Open BIM’s promise is significant. Its practical reality is more complex. Here is what experienced practitioners know that introductory articles rarely say.

IFC exports are not lossless

When a Revit model exports to IFC, the software maps Revit-specific objects and parameters to IFC equivalents. Not everything maps cleanly. Custom Revit parameters that have no IFC equivalent may be dropped. Revit family types may map to generic IFC classes that lose specific information. Complex geometry that Revit handles natively may not translate with perfect fidelity to IFC geometry representations.

IFC implementations vary between software vendors

buildingSMART certifies IFC implementations, but certification tests a defined set of exchange scenarios, not every possible use case. In practice, IFC exported from Revit may import differently into ArchiCAD than the same file imports into Tekla or Navisworks. Property sets arrive with different names. Space boundaries are interpreted differently. System relationships may be lost.

This is not a reason to abandon Open BIM. It is a reason to test IFC round-trips between the specific software versions your project will use, at the project kick-off, not when you first need to deliver.

COBie compliance is often checkbox compliance

Many projects nominally deliver COBie at handover. But COBie quality varies enormously. A COBie spreadsheet that lists every floor, space, and equipment asset but with missing type of information, incomplete job plans, or mislinked component records is technically a COBie file but practically useless to a facilities team.

Genuine COBie compliance requires that the BIM model be authored with handover data in mind from the start, that component properties are populated correctly, that manufacturer data is included, and that the model organization matches the COBie structure. This is a discipline issue, not a software issue, and it requires explicit client requirements and contractual obligations to achieve.

‘Open BIM’ does not mean free software

Revit, ArchiCAD, Tekla, and Vectorworks all support Open BIM standards. They are not free. The ‘open’ in Open BIM refers to open data standards, not open-source software. Free and open-source IFC-capable tools exist, FreeCAD, BlenderBIM, and various IFC viewers, but they are not equivalent to commercial BIM platforms for production work in most professional contexts.

Software That Supports Open BIM

Any BIM platform that can export and import IFC participates in Open BIM. The quality of implementation varies. Here is a practical guide to the main options.

BIM authoring tools with strong IFC support Where your models are created

• Autodesk Revit: The most widely used BIM authoring tool in the AEC market. IFC exports via the built-in exporter (basic) or the OpenBIM plugin (more complete). IFC4 support is available. IFC2x3 export is the most reliable for cross-platform compatibility. Widely used by architects, structural engineers, and MEP engineers.

• ArchiCAD (Graphisoft): One of the best IFC implementations in the market. ArchiCAD has historically invested heavily in IFC fidelity and is particularly well-regarded for architectural IFC exports. Strong round-trip capability. Used extensively in European markets.

• Tekla Structures (Trimble): Industry standard for structural steel and concrete detailing. Strong IFC export for structural models, including reinforcement data. Widely used in structural engineering and fabrication.

• Vectorworks Architect: Strong IFC support with good bidirectional exchange. Popular in entertainment architecture, landscape, and smaller AEC firms. buildingSMART certified.

• Bentley OpenBuildings Designer: Used for infrastructure, heavy engineering, and large complex buildings. Strong IFC support for the building domain; integrates well with Bentley’s infrastructure tools.

Coordination and validation tools Where IFC models are reviewed and quality-checked

• Solibri Model Checker: The leading IFC quality assurance tool. Validates IFC models against rules and standards, checks for compliance with information requirements, runs clash detection, and produces detailed quality reports. Essential for any serious Open BIM workflow. Now part of Nemetschek Group.

• Autodesk Navisworks: Multi-format model aggregation and clash detection. Accepts IFC alongside native Revit, DWG, and many other formats. Widely used for coordination review even in mixed-software project teams.

• BIMcollab Zoom: Free IFC viewer with BCF-based issue management. Allows any team member to review IFC models, raise BCF issues, and track resolutions, without a paid BIM authoring license. Lowers the barrier for smaller contractors and specialty consultants.

• OPEN IFC Viewer (free): Basic IFC viewing without installation. Useful for clients, facility managers, and reviewers who need to inspect model data without BIM software.

Government Mandates and ISO 19650

Open BIM adoption has been significantly accelerated by government mandates, particularly in Europe and Asia-Pacific. Understanding the mandate of landscape matters for firms working on public-sector projects internationally.

ISO 19650: the information management standard

ISO 19650 is frequently cited alongside Open BIM but is often misunderstood. It is not a file format standard; it is an information management standard. ISO 19650 defines how information should be structured, managed, approved, and exchanged throughout the design and construction process.

The standard specifies concepts like the Common Data Environment (CDE), the shared repository where project information is held, and the appointment process by which information requirements flow from client to lead contractor to subconsultants. ISO 19650 is vendor-neutral and compatible with both open and closed BIM approaches. However, IFC is the most practical format for meeting ISO 19650 interoperability requirements on multi-firm projects.

Country-by-country mandate landscape

• United Kingdom: The UK BIM mandate (2016) required BIM Level 2 for centrally funded public projects. This included IFC and COBie delivery requirements. The updated 2025 Construction Playbook extends BIM and opens data requirements to a wider range of public procurement. The UK has adopted ISO 19650 as its national BIM standard.

• Norway: Norway was among the earliest countries to mandate Open BIM, the Norwegian Statsbygg (government property manager) has required IFC-based BIM since 2010 and has been a major driver of IFC development. Norway’s public sector mandates have directly influenced buildingSMART international standards.

• Singapore: The Building and Construction Authority (BCA) has mandated BIM submissions for buildings above certain GFA thresholds since 2013, with IFC-based e-submissions for regulatory approval. Singapore is one of the most advanced markets for Open BIM adoption globally.

• European Union: The European Commission has included BIM requirements in public procurement guidance. Several EU member states (Germany, Finland, Netherlands, France) have national-level BIM programs with Open BIM components. The EU BIM Task Group promotes Open BIM adoption across member states.

• Australia: The Australian government’s National BIM Initiative and state-level procurement guidelines increasingly reference Open BIM and ISO 19650. The ACT and Victoria have included BIM requirements in major public infrastructure procurement.

• United States: No federal Open BIM mandate, but the GSA requires BIM for major projects and accepts IFC. The US Army Corps of Engineers mandates BIM for standard building types. State-level requirements vary; several states reference BIM in capital project delivery guidance.

Implementing Open BIM on Your Project

Open BIM does not happen automatically because you export an IFC file. It requires deliberate planning from the start of the project. Here are the practical steps that determine whether an Open BIM project delivers on its promise.

Step 1: Define information requirements before modeling starts

The client’s information requirements (CIR) specify what data the project needs to deliver: which IFC classes, which property sets, which LOD (Level of Definition) at each project stage, and which standards (COBie, IDS) apply to the handover. Without these requirements defined up front, the BIM models will not contain the right data at the right time, regardless of how technically capable the authors are.

Step 2: Write an Open BIM-specific BIM Execution Plan

The BIM Execution Plan (BEP) for an Open BIM project must specify which IFC version will be used for exchange, which software each discipline is using, how IFC exports will be configured, how BCF will be used for issue management, how model quality will be validated (Solibri or equivalent), and who is responsible for federation and coordination.

This is additional content compared to a standard BEP. It addresses the technical coordination layer that determines whether the IFC exchanges actually work.

Step 3: Test IFC round-trips before production begins

Before the project reaches design development, each discipline should export a test of IFC from their software and confirm that it imports correctly into the coordination platform. This test identifies compatibility issues, missing property mappings, and geometry translation problems while they are cheap to fix, before the entire project is modeled.

Step 4: Validate IFC quality at each milestone

IFC models should be validated against the project’s information requirements at each major milestone, concept design, schematic design, developed design, technical design, and construction. Solibri or an equivalent IFC checker runs the validation automatically against IDS rules, identifying missing data before it becomes a handover problem.

Step 5: Deliver COBie at handover, not after

COBie preparation is most effective when it is built into the modeling workflow from the start, not assembled from the model after practical completion. Agree the COBie template with the facilities manager before design begins, ensure component properties align with COBie field requirements, and validate the COBie spreadsheet at design stage milestones rather than discovering gaps at handover.

Open BIM: The Infrastructure for a Connected Construction Industry

Open BIM is not a technology trend. It is the infrastructure decision that determines whether the AEC industry can realize the value of digital construction, or whether that value remains locked in proprietary formats that expire with software vendors.

The business case is clearest at the project boundary: when firms with different software need to coordinate without forcing expensive platform changes. It is also compelling at the lifecycle boundary: when buildings need to be operated and maintained for 50 years, and the data created during design needs to still be accessible and queryable when the software it was created no longer exists.

The practical limits of Open BIM, IFC translation losses, variable software implementations, and the discipline required for genuine COBie compliance are real and worth understanding. But they are manageable with proper project setup, and they are improving as software vendors invest in IFC quality and buildingSMART updates the standards.

For firms working on multi-discipline projects, public sector procurement, or buildings where facility management is a genuine priority, Open BIM is not an optional infrastructure for the future. It is a practical capability for today.

Common Questions About Open BIM

Is Open BIM more expensive than closed BIM?Not inherent. Open BIM requires setup investment, writing about the BEP, testing IFC exchanges, configuring export settings, that closed BIM avoids when all parties use the same platform. But it avoids the cost of forcing disciplines onto platforms that are not their best tool and avoids the data lock-in risk of proprietary formats. For multi-firm projects, Open BIM typically reduces overall coordination of friction costs that closed BIM accumulates when firms use incompatible proprietary formats.

Does Revit support Open BIM?Yes. Revit exports IFC through its built-in exporter and the OpenBIM plugin, supports BCF issue management through BIMcollab and similar integrations, and can export COBie data. The quality of Revit’s IFC export depends on how the model is structured and how the export settings are configured. Revit’s IFC implementation is functional but has historically been less complete than ArchiCAD’s; this is worth testing your specific exchange requirements.

What is the difference between IFC and DWG?DWG is a proprietary Autodesk format for geometric drawing data. It carries 2D and 3D geometry accurately but has no standardized schema for building component intelligence. A wall in DWG is lined and hatched, not an object with properties. IFC is an open standard that carries both geometry and intelligence: component types, material properties, system relationships, costs, and operational data. IFC is significantly more expressive for building data exchange. DWG is still appropriate for 2D construction documentation where model intelligence is not required.

What does ‘LOD’ mean in Open BIM?LOD (Level of Development, or Level of Definition in ISO 19650 terminology) describes how much information a BIM element contains at a given project stage. LOD 100 is a basic massing element with approximate size and location. LOD 400 is a fully detailed element with fabrication-level geometry, all material properties, costs, and manufacturer data. For Open BIM exchanges, specifying the required LOD at each project stage ensures that models contain the right data for coordination, estimation, and handover, not more than needed early, not less than needed late.

Is Open BIM required on private sector projects?Only where contractual requirements specify it. Private sector clients can require Open BIM in their employer for information requirements, and some sophisticated clients, particularly those with long-term facility management concerns, do. But for most private projects, the choice between open and closed BIM is a project team decision based on which firms are involved, what their software environments are, and what the handover requirements are.

What is a Common Data Environment (CDE) in Open BIM?A Common Data Environment is the shared digital repository where project information is created, reviewed, approved, and archived throughout the project lifecycle. In ISO 19650 terms, the CDE has defined work-in-progress, shared, published, and archived states that control when information is available to which parties. Open BIM CDEs support IFC, BCF, and other open formats for file exchange. Common CDE platforms include Autodesk Construction Cloud, Trimble Connect, BIMcollab, and Thinkproject, all supporting IFC and BCF alongside native formats.