Open BIM vs. Closed BIM | BIG BIM vs. little BIM

calendar_16x16 09 Jun 2024 • Posted by user_16x16 Smiljan Tukić

Video & Introduction


Video comming soon…

In this blog article, we’ll unravel the differences between Open BIM, Closed BIM, little BIM, and BIG BIM. In closing, as the author, I’d like to share my perspective on the most promising path forward and the future I envision for the AEC industry.

BIM in a Nutshell and Development Stages

BIM stands for Building Information Modeling which is a collaborative process that utilizes a shared digital model to represent the physical and functional aspects of a building or infrastructure project throughout its lifecycle.

When introducing BIM, a distinction is made between little BIM and BIG BIM. These designations are further differentiated by open and closed. This results in the following combinations:

  • little Open BIM,

  • little Closed BIM,

  • BIG Open BIM, and

  • BIG Closed BIM.


Figure: BIM approaches based on the collaborative framework

What is Open BIM and Closed BIM?

Closed BIM

In Closed BIM, all collaboration and data exchange tools are provided by a single software vendor, using proprietary file formats[1]. This can offer the advantage of smoother communication between tools since they’re designed to work together. However, the significant drawback is the potential for vendor lock-in. Relying on one provider makes it difficult and costly to switch to different software, limiting flexibility and potentially increasing expenses.


Figure: In Closed BIM all tools are provided by a single software vendor.

Closed BIM can be a risky strategy, as it lacks a backup plan in case the chosen vendor encounters difficulties or fails to meet expectations.

Open BIM

In Open BIM, collaboration and data exchange rely on open, vendor-neutral file formats. The Industry Foundation Classes (IFC) format is the most widely used, enabling seamless sharing of information between different software applications.


Figure: In Open BIM, collaboration and data exchange occur through open file formats.

Beside IFC, other open formats can also be used, but the absence of standardization presents a hurdle, particularly in “BIG Open BIM” scenarios where large-scale projects involve diverse stakeholders. Establishing standardized processes and protocols for data exchange is essential to ensure smooth collaboration and interoperability in these intricate environments.

What is BIG BIM and little BIM?


This approach represents the most comprehensive BIM implementation, where professionals from diverse disciplines collaborate on a shared digital model. Various software solutions are employed, and data is exchanged seamlessly through neutral interfaces, fostering a truly integrated and holistic project workflow.

BIG BIM can be implemented using either an Open or Closed BIM approach.

At present, IFC stands as the sole file format that fully satisfies the requirements for BIG Open BIM. Its neutral, open, and standardized nature ensures a reliable and consistent data structure, making it the ideal choice for facilitating seamless collaboration and data exchange in large-scale projects. The latest IFC 4.3 is formally approved and published as an ISO Standard (ISO 16739).


Figure: BIG BIM - Diverse disciplines collaborate on a shared digital model.

While it’s technically possible to combine BIG BIM also with closed BIM, it’s unrealistic to expect optimal results unless a single software vendor excels in all disciplines. In reality, most vendors specialize in specific areas of the Architecture, Engineering, and Construction (AEC) industry, making a fully integrated closed BIM approach less feasible. For BIG Closed BIM to be viable, a platform must be provided where other software vendors can offer their services through plugins or apps, however, this approach risks pushing the AEC industry towards monopolization.

little BIM

little BIM limits collaboration and data exchange to within specific disciplines. While this is feasible, it doesn’t align with the fundamental concept of BIM, which emphasizes cross-disciplinary collaboration throughout the entire project lifecycle.

Conclusion and Author’s Perspective

No single company can claim to be the best in every aspect of the AEC industry. Collaboration and data exchange across different fields will often be necessary to achieve the best results. This is the reason why I think that Open BIM is the only right way where the AEC industry should go.

Given the vast scale of the AEC industry, we must prevent a few large companies from monopolizing the market.

Open BIM stands as the preferred path to circumvent the monopolization of the AEC (Architecture, Engineering and Construction) industry by a few software companies, ensuring greater accessibility, interoperability, and a level playing field for all stakeholders. Without the adoption of Open BIM standards, the peril of becoming beholden to a single software vendor grows, including the risk of vendor lock-in.

Opting for the Closed BIM route may lock you into costly subscription fees, leaving you with little choice but to pay up the subscriptions and accept the limitations.

The provision of IFC as a neutral and standardized file format puts us on a promising path. Mandating open formats like IFC and adherence to BIM requirements for all models would compel major software vendors to offer IFC compatibility, or risk becoming obsolete.


Figure: Authors’ illustration comparing Open BIM and Closed BIM

To conclude, reject the limitations of Closed BIM and embrace the freedom and flexibility of Open BIM.

Tags: Open BIM Closed BIM little BIM BIG BIM IFC AEC