Building Information Modeling (BIM)

We use BIM as a verb or an adjective phrase to describe tools, processes and technologies that are facilitated by digital, machine - readable documentation about a building, its performance, its planning, its construction and later its operation. Therefore BIM describes an activity, not an object. To describe the result of the modeling activity, we use the term ‘building information model’, or more simply ‘building model’.

Building Model

A digital, machine - readable record of a building, its performance, its planning, its construction and later its operation. A Revit® model or a Digital Project(tm) model of a building are examples of building models. ‘Building model’ can be considered the next-generation replacement for ‘construction drawings’, or ‘architectural drawings’. Downstream in the process, the term ‘fabrication model’ is already in common use as a replacement for ’shop drawings’.

Building Data Model

An object schema suitable for representing a building. A building data model may be used to represent schemas for file exchange, for XML - based web exchange, or to define a database schema for a repository. The main examples of building data models are IFC and CIS/2.

Some of the earlier contributors to this thread discussed certain conditions that should apply in order to qualify a software application as a BIM tool. We prefer to define the qualities of the tools and their ability to support BIM in terms of their parametric modeling and object-oriented functionality. The three conditions that Robert Anderson cites are certainly valid, but there are others, such as support for parametric behavior and team collaboration (see chapter 1, section 1.4 of the BIM Handbook for a detailed discussion and definitions).

It is perhaps easier to define what is not BIM technology, which we do in section 1.5. Among the caveats listed, are these two, which are perhaps problematic for AutoCAD Architecture:

- Models that are composed of multiple 2D CAD reference files that must be combined to define the building. It is impossible to ensure that the resulting 3D model will be feasible, consistent, countable, and display intelligence with respect to the objects contained within it.

- Models with no support for behavior.

Rafael Sacks, Chuck Eastman, Paul Teicholz and Kathleen Liston

But in the same post you stated “Revit, by far, is the best purpose built BIM application.” Then went on to state “And now that Autodesk has opened up the programing interface for this program, it will not be long before 3rd party companies develop even better tools to work with Revit.”

Ummmm, does this not then place Revit in the same position you described for AutoCAD and 3rd party development if it too is having to open up its API for 3rd party development to further enhance its BIM capacity? Sounds a bit contradictory to me.

In short, it is just additional proof that no single platform, in their currently available state, is a true BIM solution. If Revit is indeed “by far, the best purpose built BIM application” then why are the greatest majority of its sales as the AutoCAD / Revit bundle? Surely, the best BIM application would not have to rely or depend on such an archaic tool as AutoCAD just to complete 2D construction documentation?

Technically speaking, this pairing of Revit and AutoCAD then virtually makes Revit just like AutoCAD Architecture (ACA), except you don’t have to dumb down intelligent objects in ACA to get your construction documents as you do when taking a Revit file to a DWG file.

Now as far as the “True BIM” argument goes — the software is only a tool. The design process change along with the correct tools will get you to a BIM deliverable. So the argument is, which is the best tool? Here, of course, there is going to be much debate. So for simplicity I will give you the ones I am familar with.

Revit, by far, is the best purpose built BIM application. It allows one to have the most control over the information put into the model and the most information to be extracted from the model. It is the only one of the three that I list here that give you full bi-directional (Parametric) relationship out of the box leaving less room for error. And now that Autodesk has opened up the programing interface for this program, it will not be long before 3rd party companies develop even better tools to work with Revit. After reaching over 250k users in 2007 (much more now), it is the fastest adopted BIM tool on the market.

AutoCAD Arch (AA) was not a purpose build BIM application. Who knows if it will ever get there. There is limited bi-directional relationships and is mostly uni-directional which mean the user has to update portions of the model manually. This allows two much room for error. With over 500k users in the US alone, a small amount of the users use AA the way it was meant to be used. This program is very hard to learn inside out ,therefore most users never utilize its power.

ArchiCAD claims to be a BIM application as well. Unfortunately this is as true as saying AutoCAD Arch is a BIM application. They have the same technology used in both programs. Technology that is now 25 years old. You have limited bi-directional relationships in ArchiCAD and more uni-relational. Once again, too much room for error. Now with that being said, ArchiCAD is a much easier program to learn than AA and many of the users see the power behind it faster than they do AA. However, ArchiCAD has only a fraction of the users that AA or Revit have in the US I would stick with Revit or AA if you plan on going to these technologies.

One more thing to mention. Neil C. Katz of Skidmore, Owings & Merrill, LLP talks about AutoCAD and BIM in his article. The problem there – in order to do the type of work he is doing with AutoCAD you need to have custom lisp routines and 3rd party programs to do what he describes. Not many firms have the knowledge, time, or money to customize AutoCAD to that extent. So AutoCAD will not cut it when it comes down to it for BIM. Not only that, he did not mention that his firm was one of the first to quickly adopt Revit and designed the Freedom Tower in NY city using Revit Technology. ArchiCAD was also used on this project and was dumped during the design phase with too many problems.

Hope this helps.

I agree with many points made here and in the original article. However, I agree most with Lachmi’s point about BIM’s being a process rather than a product. After all, Mervyn’s firm was doing BIM with R14 and a variety of other supplemental applications years ago. So it is not so much if AutoCAD Architecture is BIM or not but rather if the folks using it aspire to BIM and are comfortable implementing BIM with an “AutoCAD based tool.” Revit is often referred to as being “purpose-built” for BIM. This is true. Revit is designed with BIM in mind but more importantly, much of what BIM requires (like the items Robert points out) is built into Revit and much of its content out-of-the box. However, despite this, one could still quite easily use Revit in a “non-BIM” way. Just because it is “purpose-built” does not mean that one is required to use it for its intended purpose. Knowledge of what it takes to achieve BIM comes first followed by the intent to achieve it. Both are required.

This brings us back to AutoCAD and AutoCAD Architecture. While neither product is “purpose-built” for BIM, nothing prevents them from being utilized to facilitate a BIM process. However, as Richard pointed out, the definition of BIM is often a “controversial and debatable topic” and as Lachmi pointed out, it is still a “work in progress.” This is precisely the value of AutoCAD Architecture. Whether or not it is or should be a BIM product is really beside the point. While folks like me have very strong opinions on the “correct” way to use AutoCAD Architecture, the fact is that one of its biggest strengths is that it can be easily adapted to way that you and your firm prefer to work. This is largely inherited from its AutoCAD core. In fact, I have often joked in my classes that both the best and worst feature of ADT/ACA was that it was built on AutoCAD (as Scott pointed out in his review); I offered the observation more as an anecdote. I think that for most users, the value of the AutoCAD platform within AutoCAD Architecture cannot be overstated.

Anyhow, ruminations aside, I think if we look to the meat of Mr. OnStott’s review, we will find a very clear and concise outline of the many new features found in AutoCAD Architecture 2009. When so focused, there is much to be excited about. I think that the most valuable benefit of AutoCAD Architecture continues to be its ability to allow a firm to evolve its process beyond the creation of several disconnected and static drawings created primarily from primitive geometry to a process of more interconnected parts built from purpose-built AEC objects. With this in mind, the fact that this release focuses so heavily on making staple objects like Walls function the way that users expect is a huge boon for productivity.

AutoCAD Architecture is about choice. Choose to work as you always have using mostly AutoCAD methods and tools; choose to implement AEC objects to enhance drawing quality, accuracy and speed; or choose to use the product like BIM. In any case, the advantages over ordinary AutoCAD are tangible and worthwhile.

- BIM is more about a process than a product. That is why some firms have been able to achieve it even without the use of what we commonly refer to as “BIM” solutions. A great example of this is Neil Katz’s work with AutoCAD at SOM which he described in his Viewpoint article last year: see
http://www.aecbytes.com/viewpoint/2007/issue_32.html.

- At the same time, solutions that have been built from the ground up with the BIM concept definitely have the advantage of making it easier to do BIM than solutions which do not. This is an important aspect to consider for firms who have been doing 2D CAD all this time and are now looking to move to BIM.

- BIM is still a work in progress, and I foresee that it will continue to be for quite a while, simply because there is still much we can do to make our tools smarter, faster, and more efficient. This is true for all the solutions, including Revit, ArchiCAD, and others.

At a previous company I would say that we were close to true BIM and used a mix of tools like AutoCAD (yes even 2D P&ID, etc. is a part of BIM or in our case, maybe it should be called PIM, with P as in Plant), AutoCAD Architecture, 3rd party applications for AutoCAD, PDMS, NavisWorks, and engineering database applications to tie things together and communicate object data to purchase systems, etc.

True BIM is a methodology that enables the user to put in as much information as they see necessary or reasonable, then pulling that information out and applying it to a costing database or quantity comparision. Architecture Integrated has developed a methology that works great with 2008 and will be ported to 2009 that will do just this.