BIM QnA with Ralph Montague – Clarifying and Explaining BIM


Is BIM a process or a software? Is BIM all about 3D models or all about information? Can a well-organised folder of PDF documents be considered BIM? There are many other such questions by people new to BIM, so has asked Ralph Montague, Managing Partner of ArcDox, Ireland’s leading BIM consultancy specialists, to help clarify and explain BIM.

Ralph, what does “BIM” mean?

BIM could mean building information modelling – “modelling” is a verb, and action; something we do – so it involves a “process”. BIM could mean building information model – “model” is a noun; a thing; something we produce; a “deliverable” we manage and share. It does involve a process, it does involve software, it does involve 3D models, data and documents. BIM is the acronym that has been used and is now accepted to encompass all those things. It depends on the context in which the acronym is used.

What is a Building Information Model?

BIM is a digital representation of both the physical and functional characteristics of a building, or piece of built infrastructure. It is a shared knowledge resource of information about the building, forming a reliable basis for decisions during its lifecycle; from earliest conception to demolition.

What does that mean?

BIM is a “digital copy” of the physical reality – a “virtual” building. It is constructed in software from objects or components that represent their real-life counterpart. Each object in the BIM is a “container” or placeholder of digital “information” about that element of the building. In other words, everything you need to know about that element of the building is contained or referenced from within the object itself. Information about its physical aspects (such as size, weight etc), to its functional aspects (such as its performance and relationship to other systems etc).

Since all this information is produced, managed and shared from within this “digital copy” of the physical asset, it can easily be kept up-to-date, in one place. And since it is “digital” information, it can easily be searched and queried using computers, in many ways, to provide a reliable source of information for business processes and decision making, including building, operating, maintaining, analysing, responding, transacting, and de-commissioning.

Is a 3D-model a BIM?

Not necessarily. 3D-models can be created in many different ways. They could be created using lines, planes (or faces), meshes, or points in 3 dimensions (length, width and height). When viewed in software, all of these will look like a digital representation of the building. But individual lines, planes, meshes or points don’t necessarily represent a distinct real-life “object”, component or element of the physical building, so we can’t attach “information” or data about that building element or component to the 3D elements. A 3D-model comprising of lines, planes, meshes and points, can represent the “physical” characteristics of a building (like size, shape, position), but cannot represent the “functional” characteristics of the building elements (like their performance, relationships to other systems etc). In order to be a BIM, it has to do both, and therefore “object-based modelling” is a key characteristic of BIM, as you can then attach information or data to the distinct objects. BIM software does all this for you.

In theory, you could spend a lot of time grouping lines, planes, meshes and points from CAD or non-BIM 3D-modelling software, into distinct blocks or objects, and then name and attach information to these, but the time and effort wouldn’t be justified, and at the end of the day, you’d have to make sure these can somehow be exported to an open “object-based” format like IFC (Industry Foundation Classes), for sharing with others.

Can you have BIM without a 3D-model?

Some people have argued that having well-organised information, or data and documents, can be called BIM. This is the opposite situation to the argument above. A well-structured digital data set can give you all the “functional” characteristics of the distinct building components (such as performance, and relationship to systems), as well as a written description of some of the physical characteristics (such as size), but the physical location of components in relationship to each other would be very difficult to describe or visualise in words or text. Of course, it is possible to describe that a piece of equipment is “on the 5th floor, in room 510, in the left-hand corner, if you are facing the external window on the north side, 1 meter above the floor, connected to the supply ventilation system fed by air handling unit 3”, but doing this for every component in the building would be very tedious work, and not feasible. But since, when designing and constructing the building, you have already located or placed that component in a location in the model, why not just reference that model information? So, the relationship between the model (geometry or graphic data) and the information (non-graphical data) is an important characteristic of BIM.

Can Documents be called BIM?

While we are moving away from paper-based processes to digital processes, certain information will continue to be contained in documents or files, for a long time to come. Output drawings, schedules and bills of quantities will remain the “record” documents of contracts and transactions. A legal agreement, a test-certificate, an instruction manual, a detailed text specification – these are examples of “documents” that will not be contained in the 3D BIM but are still very relevant information to the building. Firstly, some of these don’t directly relate to a specific building element or component, and therefore cannot be inserted or attached to a distinct “object” in the model (like the legal agreement for example). Others may relate to specific building elements, but it would not be useful, or feasible, to insert these into the model as “data fields”, because of the amount of data (text and graphics) contained, and the format in which you would prefer to use that information (like the operating instruction manual for example). In this latter case, you can insert a “hyperlink” to the relevant document, into the “object” in the BIM, for ease of reference, but the document itself will be stored elsewhere. The “information model” as described in PAS1192-2, is the combination of the Graphical Data, Non-Graphical Data and Documents. So, documents are a key part of BIM, but documents by themselves do not describe a complete “information model”.

Is BIM a Process or a Software?

As described earlier, BIM is both a process and deliverable. BIM involves software – it is not possible to produce a BIM without software, and since BIM is a collection of “digital” data (graphical, non-graphical and documents or files), BIM has to be managed within software. But BIM isn’t one piece of software – you can’t go and buy “BIM” off the shelf. A lot of different software is involved, depending on what you are doing.

Also, producing and managing a “digital copy” of the physical building is not going to happen by accident. There has to be a clearly defined and carefully managed “process” put in place, that requires everyone participating on a project to make their inputs in a way that can be brought together to form the “digital copy” of the physical building. Without this “process”, BIM is not going to happen. Whose responsibility is it to make sure this “process” is put in place? Some argue that it is up to “clients”, others argue that the professional teams that clients employ or hire, should be making sure this “process” is put in place, on the client’s behalf. Our own experience suggests, that if it is not a clear “client requirement” to build this “digital copy” of the physical building, then it is seen as “optional” by some and at some point, the process breaks down, or the “digital copy” is incomplete.

Why do we need a “digital copy” of the real building?

Buildings, or built infrastructure, are complex things. During the design, construction and operations of buildings, many people need to continually have access to “information” about the building, and its components, to do their job. They need to be sure that information is relevant, accurate and useful (i.e. they don’t need to do a lot of additional work, or re-work, before they can use the information to do their job). When information is stored in “paper” documents, a few things happen. First, you are not sure if the information is accurate or up-to-date (since static or paper-based documents cannot be easily updated) – so you don’t, or can’t necessarily trust the information. Secondly, in its static or “paper” format, it is difficult to query, or extract the relevant information you need to carry out a particular task, without first reading it with your eyes, and then re-typing, or reproducing it in your own tool for carrying out your task. This introduces a duplication or re-work cost, as well as the opportunity to introduce human error in the transcription. Lastly, if your task highlights a need to update the central resource of information, it is unlikely to be recorded, as it would involve too much work to update the static or “paper” document. So, over time, more and more inconsistencies occur, and the central information source gets degraded and depleted, losing its value. This doesn’t have to be like this. We live in the digital information age. We have the tools and processes to manage information in a much better way, in the “digital copy” of the physical asset. This will bring about vast improvements in efficiencies, productivity and business intelligence. In our “digital future” every building will have a BIM, and every built asset will have a “digital copy” of itself as an intelligent information resource for smart business. 

“…in our digital future, every building will have a BIM – a digital copy of itself…” 

Ralph Montague, ArcDox

So, in summary, BIM is a process, it involves software, it comprises digital 3D geometry (graphical data), information (non-graphical data) and documents, all related to “objects”, elements or components of real building and built infrastructure. You can’t separate any of these elements and call it BIM.

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