F the Ds!

Enough! No more using the Ds to describe what you are doing with BIM! Please just tell me what it is that you are trying to use BIM to accomplish, and more importantly WHY. It is the why, the reason or the purpose that is the most important. You are either using BIM to gather, to generate, to analyze, to communicate, or to realize information about the facility. From there, you can add a more detailed purpose or you can begin to add the who, what, and when into the equation. Please, just no more Ds!

Currently, I think the Ds go something like this: 3D – Geometry, 4D – Time, 5D – Money / Estimating, 6D Energy or maybe Facility Management depending upon. Once you get past 3D or 4D, you've lost me. So you might ask, what is my issue with the Ds? Primarily, it's their lack of descriptiveness. Adding a D behind a number does not create a BIM Use. A question I have is where does coordination fall? Is it assumed that this just falls into 3D? What about the modeling itself? These are the two most common uses of BIM, and they don’t fall anywhere within the Ds. If you look at the BIM Project Execution Planning Guide and their BIM Uses, would there then be 25 different Ds? Do we have a D for digital fabrication, digital layout. Or how about code validation, or design review. What D are they?

And don’t even get me started on the sixth D (or seventh depending upon who you are talking to): Facility Management. What narrow minded designer or contractor had the gall to classify an entire phase of the facility lifecycle into one D. Not to mention that it is typically the longest and most costly phase of the facility. If that were the case, maybe we should call BIM for design the seventh D and BIM for Construction the eighth D. Can you see what happens when we start arbitrarily mixing different types of items?

Everyone says BIM changes everything. It does not. It is just another evolution in the process. We are still planning, designing, constructing, and operating facilities. That has not changed. It is, however, a different way of thinking about a facility and it allows us to finally put the facility (the product itself) at the center of our conversation where it belongs. Rather than all the other wasted efforts within our industry.

So therefore, the purpose for each of us does not change. BIM does not change the purpose for the activity only the means by which we achieve it. BIM is simply a means to an end. While I would argue it's the most effective means, the bottom line is that BIM is still just a means to do what we do better.

So what we really need to start talking about, instead of the Ds, is the purpose. What is your purpose for implementing BIM? What are the specific objectives that you are trying to accomplish using BIM? I would bet your response could be classified into one of five categories. We use BIM to do any one or combination of the following: GATHER, to GENERATE, to ANALYZE, to COMMUNICATE, and to REALIZE information about the facility.

It’s as simple as that. These are the basic reasons or purposes for implementing BIM. Remember: The most important thing is to ensure that your purpose has been communicated. Nothing more, nothing less.

Look for follow up posts as I get into the details about what are the purposes of BIM. And if you're wondering, Yes - we've posted about this before. Fellow Epic-BIM contributor, John Grady posted his perspective in What's up with all the damn D's? We obviously have opinions on the matter, and we bet you do to... what are your thoughts, do you think the use of the D's adds value? Or are you on the party bus with us... F the D's!


  1. These insights make sense.  I still believe that BIM is indeed an incredible tool which helps so much in the construction of buildings and even infrastructures.  Contractors, engineers as well as architects really find this so useful since this promotes great precision on outputs.


  2. Way to go way off track John. Could you be more esoteric in your response?

    I can see Dennis's argument from the sales side. That's why the D's were invented in the first place. The problem (as illustrated in the post above) is that although the D's might have helped sell BIM when it was in its infancy, now they just confuse the matter since the discussion requires a little more sophistication. The D's served their purpose but are now just making it harder to actually perform the work. Like Erik said above we need to be understood. The D's are getting in the way of that.

  3. Sometimes our need to clarify things and simplify things gets in the way. Often, explaining something simply can be mistaken for understanding which is not always the case. Over simplification is dangerous, it waters down what we really mean. We should say what we mean rather than trying to make sure we sound intelligent by using the current buzzwords.

    Whether that's the Ds or LOD or BIM, when generalized and used so freely they create more confusion than they erase.

  4. Dennis I ask you this what if the group of people back in 1958-1968 decided to just go along with it. Where would we be? For all of our international friends I am sure you have similar instances in your history I just point to one example I am very familiar with.

    • Right, but often times many get stuck on the small battles that mean very little in the grand scheme of winning the war. All I am saying is pick and choose. I agree the "D's" are a waste of time and at the end of the day there is only one "D" that truly matters… DATA!

  5. Ralph,

    Great post…! I do understand the marketing side of this and for those that specialize in a particular area, it makes sense. Even though I am advocate for removing the "D's", sometimes it is just easier to go along during conversation. Having to pick and choose your battles.

  6. Amen! YES! Right ON! and You Betcha! I have hated the D's since 5D, for all of the reasons mentioned.

    Just say what the model is to be used for. What can I rely on particular system in the model to accurately portray and what are you OK with me using it for.

    What is my "right of reliance?"

    No MORE Ds. Don't be cute. Be understood.

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