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Open and Closed BIM Systems

Matej Svrček

Project Management

The digitalisation of the building industry marked the shift from 2D drawings to intelligent 3D virtual models that brought data to the fore. This provided stakeholders in the construction sector with more information and unlocked a host of new possibilities, but it also brought a new set of challenges.

It is important for the market to have a clear understanding of the opportunities that Building Information Modeling (BIM) process holds, and the advantages and disadvantages between open and closed BIM systems.

Let’s get the facts straight on the divided nature of the BIM landscape

Matej Svrček outlines the benefits of BIM systems and the fragmented landscape that serve as a challenge in a consultant
BIM and eCAT Manager , Systemair
MagiCAD Model

Building Information Modeling (BIM) is an intelligent 3D model-based process that helps participants manage the shared information of a project through the digital representation of the built object. It provides the architecture, engineering and construction (AEC) sector with the ideal insights and tools to more efficiently collaborate, design, construct, and manage buildings, while saving costs and promoting a more sustainable workflow.

A good BIM model with the necessary information helps all participants streamline project development, execution and construction, all the way to handover and facility management.

BIM is the key to greater collaboration and transparency and serves as a glue that holds design and construction together.

However, currently, the BIM landscape remains very fragmented for several reasons:

  • Absence of a universal standard in the information required and how the model should look like

  • Disjointed model and data exchange - Information might get lost or be incompatible due to different softwares, approaches and standards

  • Different levels of BIM development in different countries

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What are the challenges for consultants?

This serves as a challenge to consultants who are wary about accepting new software and deciding on which to use, as it would cause issues related to:

  • Training and flexibility - the shift to new softwares and approaches requires skilled human resources

  • Cost and time - the purchase of new licenses and building new working methods takes considerable investment in capex and opex

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What are the challenges for manufacturers?

From the manufacturers’ side, navigating the fragmented BIM landscape can also be a challenge for the following reasons:

  • Need to supply models for all available platforms, and there are too many players to consider

  • Addressing the requirement for information that may be useful for some markets and designers but unnecessary for others

  • More information leads to a bigger model that may overload the consultant making it even more difficult to choose, but on the other hand, the lack of needed information is similarly harmful

What is the difference between Open and Closed BIM?

At the moment, everyone is free to use any software. This has led to two distinct models, each with its own set of advantages and disadvantages:

Closed BIM system

A closed BIM system means that consultants and stakeholders are working solely on one platform, often even in the same version of the software. The advantage here is avoiding loss of information during data exchange, or incorrect transfer of objects. This approach is usually more suitable for SMEs.

Open BIM system

An open BIM system means project members can have access to the information model through an open format. It offers a more collaborative approach and it is based on open standards, such as IFC. It means that even if an HVAC consultant works with Autocad or Revit, they can export an IFC file which everyone can view in a free viewer and share to other stakeholders. This provides deep interoperability and cooperation based on data exchange. It is mostly used on bigger projects.

Why is it necessary to move towards one standard?

The advantage of open BIM is that we can answer more needs of consultants by providing more formats, but it also makes it challenging to make all those formats. For Systemair, we support both, open and closed, as two pillars of our BIM strategy.

In an ideal world, it would be best to have an international or regional (e.g., European) BIM standard, that could present a shared file on parameters and information, and a common format that can be used by everyone. There are international initiatives aiming for such a standard. This is related to information on what parameters should be in the model that would address the requirements of the consultant, while remaining feasible for the manufacturer. However, these initiatives are not necessarily HVAC-related and are rather general. We do not have, for example, a European classification of which parameters should be included in air handling unit BIM files.

There is progress that has been made by local associations like BIM association Slovakia (BIMaS), which has been successful in sharing knowledge and cooperating on important issues related to European BIM. Local BIM associations play an important role in sharing BIM knowledge and bringing partners together. Mandates are also important to push for rules and cooperation on a national level. This then leads to better coordination of international standards.

At the moment, we are lacking a proper multinational cooperation on HVAC-related BIM standards. The risk of having a complex patchwork of differing national BIM standards and software providers is real and should be avoided by all means. Major global, building-related HVAC associations, such as ASHRAE and REHVA, should step up their game in taking a better ownership here. At the same time, manufacturers‘ associations, such as AHRI and Eurovent, should define unified, product-related attributes.


Although the transition might seem difficult, time-consuming and costly, the advantages of using BIM greatly outweigh the disadvantages. Utilising BIM can drive tremendous growth in productivity, optimise cost, provide transparency and move the needle in meeting sustainability objectives, via precise cooperation in a common data environment. The use of BIM will also lead to better building performance and operation following better decision-making and facility management.

Although the BIM itself is still fragmented, which deserves to be solved on an association level, we can already answer the BIM requests of many customers in cooperation with providers and BIM experts like MagiCAD. We can, step by step, bring them extended and better solutions, which should help all users, from beginners to experienced ones.

In conclusion, BIM will be the future of the building industry, serving the whole life-cycle of the building and because of its great advantages we should support and promote the idea of BIM.

While our recommendations are based on the best available evidence and knowledge (including our own internal knowledge as one of the world’s leading HVAC manufacturers), the Systemair Group excludes any liability for any direct, indirect, incidental damages or any other damages that would result from or relate to the use of the information presented on this page.