Open BIM

What is the open BIM definition?

Building information modeling (BIM) is a process involving the generation and management of digital representations of physical and functional characteristics of a facility. The resulting building information models support decision-making about a facility from earliest conceptual stages, through design and construction, and its operational life and eventual demolition. This process is supported by various tools and technologies. Building information models are often files but not always in proprietary formats and contain proprietary data that can be extracted, exchanged, or networked to support decision-making regarding a built asset. This information is shared either through open BIM or closed BIM format. So, what is open BIM and why is it important, let’s understand.

Open BIM is a format that allows each and every project member to access the information model without hampering the native design. It is a universal approach to collaborate with design, realize, and operate buildings based on open standards like IFC, BCF, and others.

To have a better understanding, let’s take a concrete example. When we write a document and want to share it with someone, we usually send it in PDF format. The PDF format allows to see the document, add comment and suggestions but keep the original text or visuals unchanged. However, it is not the same as when we share that document in a word format. It is easy to change the original text in that way. Same is with BIM. Here we create a model and then we send it to all project members. If we share it in native file format chances are that anyone can make changes in the original model. But, when the model is shared in open BIM format then the data of it is viewable, measurable, and usable, and the model content is protected. The original file cannot be altered by any other member. Open BIM supports transparent, open workflow, allowing project members to participate in it regardless of the software tools they use. It is an approach — a philosophy that empowers all industry stakeholders to participate with meaningful, bi-directional workflows, resulting in better buildings.

What are the key open BIM standards?

The foundation of open BIM lies in its reliance on open standards developed and maintained by organizations like buildingSMART. These standards act as common languages, enabling different software applications to communicate and exchange data effectively. The most critical include:

• Industry Foundation Classes (IFC): IFC is the primary open standard for open BIM. It is a vendor-neutral file format for exchanging BIM data, providing a standardized data model for describing building information. This includes geometry, material properties, and relationships between components. When a model is exported to an IFC file, any IFC-certified software can import and interpret it correctly. This ensures interoperability, allowing models created in one software to be used for analysis, quantity takeoff, and coordination in another without data loss. buildingSMART manages IFC’s development, ensuring it evolves with industry needs. The use of IFC files is crucial for maintaining data integrity across diverse software environments.
• BIM Collaboration Format (BCF): While IFC handles model data, BCF is an open standard specifically for communication and workflow management. BCF facilitates communication exchange between different BIM software platforms. For instance, if a team member finds a clash in a model, they can create a BCF file containing a view snapshot, a comment, and a link to the specific element in the IFC model. This file is shared, allowing the recipient to open it in their software, navigate to the issue, and address it. BCF streamlines communication, avoiding back-and-forth emails with screenshots, making coordination faster and more efficient. It is an essential component of a collaborative open BIM workflow, ensuring clear and trackable issue resolution.
• Information Delivery Specification (IDS): IDS is an open standard that formally defines information requirements for BIM projects. An IDS file specifies what information should be included in a model at different project stages. For example, an IDS can mandate that all doors must have specific properties (e.g., fire rating) populated by a certain date. This standard ensures exchanged information is complete and meets project needs. IDS works with IFC and BCF to create a structured, quality-controlled data environment, aligning deliverables with client requirements. IDS files are machine-readable, enabling automated validation of BIM models against specified requirements, significantly improving data quality and reducing manual checks.

These open standards exemplify the open BIM philosophy: they are non-proprietary, publicly available, and developed by a global community. This benefits the entire industry, fostering innovation and collaboration impossible under closed, proprietary systems. They align with ISO 19650 standards, reinforcing their quality and reliability in managing BIM workflows.

The core values of open BIM for construction projects according to buildingSMART

According to buildingSMART, an international organization leading the digital transformation in the construction industry, open BIM is based on 6 core values:

• Interoperability is key to the digital transformation in the built asset industry.
• Open and neutral standards should be developed to facilitate interoperability.
• Reliable data exchanges depend on independent quality benchmarks.
• Collaboration workflows should not be limited by proprietary processes or data formats.
• Flexibility of choice of technology creates more value for all stakeholders.
• Sustainability is safeguarded by long-term interoperable data standards.

What is the difference between openBIM and closed BIM?

Feature	Closed BIM	Open BIM
Definition	A methodology where all project stakeholders use a single, proprietary software platform from one vendor.	A universal approach to collaboration and data exchange based on open, vendor-neutral standards and workflows.
Core Principle	A unified and controlled environment where all data is natively compatible within a single software ecosystem.	Interoperability and data sovereignty, allowing all stakeholders to choose their preferred software while still collaborating effectively.
Data Format	Proprietary formats (e.g., .rvt for Revit, .dgn for Bentley), which can only be read and edited by the originating software or a compatible one.	Open, non-proprietary formats like IFC (Industry Foundation Classes) and BCF (BIM Collaboration Format).
Collaboration	Collaboration is seamless within the single software ecosystem, but is often difficult or impossible with external teams using different software.	Collaboration is flexible and inclusive, allowing project members to work together regardless of the software they use. Facilitates communication across disciplinary barriers.
Interoperability	Low. Data is locked into a single software environment, leading to data loss or conversion issues when trying to exchange information with other tools.	High. Open standards ensure that data can be easily shared and reused across multiple software platforms.
Flexibility	Limited. Teams are restricted to a single software, which can hinder innovation and the use of specialized, “best-of-breed” tools.	High. Stakeholders can use the software that is best suited for their specific task (e.g., structural analysis, energy simulation) and still share data.
Cost	Can have higher upfront costs due to expensive proprietary licenses, but may offer a more streamlined, single point of support.	Can be more cost-effective as it allows teams to choose a mix of software solutions, avoiding vendor lock-in and high license fees.
Data Longevity	Poor. Project data is tied to a specific software version. If the software is no longer supported or a team member lacks the license, the data may become inaccessible.	Excellent. The use of open standards ensures that project data remains accessible and usable over the long term, making it “future-proof.”

What are the benefits of open BIM?

Adopting an open BIM approach offers numerous benefits impacting every project stage and stakeholder, extending beyond technical interoperability to fundamentally improve collaboration, efficiency, and long-term asset management.

• Improved Collaboration and Communication: open BIM supports transparent, open workflows, allowing project members to participate regardless of their software tools. Using IFC and BCF as common languages, all disciplines work with a shared model understanding. This eliminates data silos, reduces miscommunication, and accelerates decision-making. BCF for issue management, for example, enables precise, trackable communication about design conflicts, leading to faster resolution. This fosters a truly collaborative environment vital for complex construction projects.
• Enhanced Interoperability and Flexibility: open BIM creates a common language for widely referenced processes, enabling transparent commercial engagement, comparable service evaluation, and assured data quality. Small and large software vendors can compete with independent systems. This flexibility means project members choose “best of breed” solutions for their specific needs, avoiding vendor lock-in. This leads to more innovative solutions and better project outcomes.
• Data Longevity and Accessibility: open BIM provides access to BIM data throughout the built asset’s lifecycle. Unlike proprietary formats that can become obsolete, open standards like IFC ensure valuable project data remains accessible for decades. This is crucial for facility management, maintenance, and future renovations, providing a robust foundation for a long-term data strategy. It also enables an accessible digital twin, continuously updated and utilized throughout the building’s operational life, contributing to better sustainability.
• Increased Efficiency and Cost Savings: By enabling seamless data exchange and improved coordination, open BIM helps reduce errors and rework, major sources of cost overruns and delays. Clash detection, facilitated by interoperable IFC models and BCF communication, identifies and resolves issues early, preventing costly on-site surprises. This streamlined workflow leads to accurate cost estimations, better resource allocation, and faster project delivery.
• Innovation and Digital Transformation: open BIM energizes the online product supply side with more exact user demand searches, delivering product data directly into the BIM. It facilitates a common data environment, offering opportunities to develop new workflows, software applications, and technology automation. This open ecosystem encourages industry-wide innovation, driving digital transformation and pushing the boundaries of building design and construction.

What are some real-world applications of open BIM?

Open BIM is becoming increasingly important in the Architecture, Engineering, and Construction (AEC) industry, with several real-world applications. When supported by a Common Data Environment (CDE), which provides a centralized platform for managing project information, open BIM becomes an even more powerful tool. The combination allows different stakeholders in a construction project to work together seamlessly, regardless of the software they’re using.

Enhancing Project Collaboration

Open BIM allows different stakeholders in a construction project to work together seamlessly, regardless of the software they’re using.

• In the construction of the Viking Ship Museum in Norway, project partners used Catenda Hub, a collaboration platform built on open BIM principles. This allowed all stakeholders to access and share design models and project data in a standardized format, even though some team members were using older software versions. The models contained both geometry and components, which helped the team manage the project’s complexity.
• Catenda Hub has been used in projects with over 171 IFC files at one time, demonstrating its capacity for handling large amounts of data from various disciplines. This enables teams to check the status of a project in a centralized way, and they can even use Robotic Process Automation (RPA) to update models daily.
• The Schweinfurt State Building Authority in Bavaria used open BIM to help its employees understand the project’s big picture. By using a Common Data Environment (CDE), project managers who don’t work with authoring software could easily view and inspect models, giving them a better idea of what electrical and ventilation planners were doing. This helps reduce errors and ensures all stakeholders are on the same page.

Streamlining Workflows and Data Management

Open BIM streamlines data management and workflows by centralizing information and ensuring its long-term accessibility.

• The nesseler group in Aachen, Germany, created a dedicated digitalization department to handle openBIM, showcasing its commitment to this approach. For them, open BIM was the only option because it guarantees data sovereignty, meaning they can access project information without being tied to a specific proprietary software.
• Open BIM allows for the integration of various tools. For example, a project at the University Hospital Cologne used an open API to connect a CDE with the company’s quality assurance system. This enables access to the rich information embedded in the plans, making the data more usable.
• The Schweinfurt State Building Authority is even developing special dashboards in collaboration with Catenda to help employees quickly find the information they need. They also want to integrate functions like field management for construction sites and GIS adaptation to manage sustainability information throughout a building’s lifecycle.

Improving Decision-Making and Cost Control

By making project data more transparent and accessible, openBIM can help improve decision-making and manage costs.

• When the Viking Ship Museum project faced a budget increase, Statsbygg, was able to use the open BIM model to identify potential cost-saving measures. Since the work had already been done and the data was stored in open formats, the team could easily reintroduce previously removed features, saving time and money.
• Open BIM also helps create As-Built models that contain all the information needed for a building’s operation and maintenance, making it easier to manage the facility after construction is complete.
• Customizable fields within a CDE allow project coordinators to control the type of information included in an issue, which leads to more accurate data. This data can be transferred to business intelligence tools like PowerBI to create detailed visualizations, helping teams prioritize and address issues more effectively.