Quantifying Revit MEP Efficiency

December 20th, 2013

Autodesk® Revit® MEP has reached the point in software development where designing a project in BIM is more efficient than drafting in 2D.  Some of you are nodding your head…but which way?  Some readers agreed with this point years ago, while others still don’t believe the hype.  The main component to this statement is user efficiency.

Let’s start off with a simple analogy: A teenager is learning how to drive a car and the instructor is trying to figure out why they’re moving so slow.  Some of us might jump to a few quick conclusions such as the car is in the wrong gear.  Jumping to conclusions is natural, but it’s important we don’t get hung up on that one answer which to us seems obvious.

This same reasoning can be applied when we ask, “How can we increase our Revit MEP user efficiency?”  My job description is mechanical engineer, but I also take on the Revit MEP SME (subject manner expert) duties.  This has allowed me to see the BIM management, the graphical standards, and the engineering design point of view.  These different positions have made me realize there are three main ingredients that can make or break a Revit user’s efficiency: Knowledge, Level of Detail (LOD), and Standards.

Knowledge

Back to our analogy. If the student driver doesn’t know how to shift gears or unlock the emergency brake, I would categorize this as knowledge of how the car operates and what its capabilities are.   In the Revit MEP world, this might be the most important ingredient to boost one’s efficiency.  Let’s break knowledge into two subcategories. 

The first subcategory is simply how much a user already knows about Revit MEP.  Understanding this software is first being familiar with its commands.  An example is modeling ductwork three different ways: 1) Right-clicking on an airflow connection; 2) Clicking the ductwork icon under the System tab; or 3) Using the keyboard hot keys.  Once the commands are mastered, knowing better processes and workflows is the next level of being more knowledgeable. 

The second subcategory of knowledge involves comprehending Revit MEP’s capabilities. Even if you’re an avid Revit user and seem to be efficient, it’s great to know what this software can do.  This is slightly different from the first subcategory, which includes what you already know.  You may not know how to do energy analysis, clash detection, pressure drop calculations, lighting analysis, or shared parameters for schedules, but after reading several AUGIWorld issues or attending a user conference, you at least know that Revit can do this.  Later on you can decide if you want to pursue training in these advanced areas.  But be careful: Just because you can do it doesn’t mean that you should do it for every project.

So if you were asked how well you know Revit MEP, what would you say?  The answer to this question is relative.  If you are your firm’s Revit “go to” person, you probably know all there is to know about Revit MEP, or at least you think you might because no one else there knows more than you.  However, if you have gone to a regional BIM conference or better yet, a national conference (i.e., RTC or AU), you quickly become humbled because you probably learned a faster workflow or a new modeling command.

Model LOD

Again back to our slow teenage driver analogy. The teen could be driving slowly not due to a lack of knowledge about the vehicle, but because of over-analyzing. Checking the blind spot eight times is really safe, but it is also causing the driver to slow down.  Just checking it once or twice will accomplish the same task, right?  In the Revit world, MEP engineers or technicians can very easily get sucked into applying too much level of detail, or over-modeling. 

On one hand, we don’t want to provide too little detail in our model so that physical attributes are misrepresented and result in problems during construction.  On the other hand, the engineers shouldn’t put too much detail into a model, especially if the model is not part of the final construction documents. 

There are many levels of detail charts and tables defined by professional organizations (i.e., AIA), large clients (universities), or design firms.  Often these charts are too vague, so specific LOD charts were developed that go one step deeper to describe what should be modeled at what level.  Below is an example of a specific LOD chart for the mechanical and pluming trades.  This goes one step deeper than most LOD charts, which often don’t help the MEP production-level users.  The chart below still gives users freedom to model how they like, but also ensures they meet a certain baseline that other disciplines depend on for coordination.

Standards

Let’s say our young driver has full knowledge of the car, doesn’t over-analyze, but he or she is still driving slowly. Why? The final reason is because the driver didn’t see the speed limit sign or chose to ignore it.  This is the last ingredient that optimizes efficiency: BIM standards.  Of the three efficiency factors, Standards fall short the most often.  This is usually the case for a few reasons.

  1. Users like the freedom to model however they choose, not caring about standards.
  2. Workload is so high that there hasn’t been any time to spend on the overhead needed to create standards.
  3. Modifying standards is boring and not part of many users’ job descriptions.

Overlooking Standards will result in an inefficient Revit user.  Ironically, the same users who lack standards are the ones who criticize that the use of Revit MEP slows them down, when in fact, if correct standards are in place, users won’t believe how much time they can save over the entire project. 

There are two subcategories of standards. The first has to deal with the traditional 2D symbology.  Examples of this are text, line weights, equipment tags, abbreviations, etc.  Most likely before Revit came on the scene, you had well-developed line styles and equipment templates.  

Even if your company had great 2D standards from your previous 2D platform, it still takes some effort recreating these standards in Revit MEP.  Just for the simple exercise of creating a mechanical equipment tag, one has to make sure the correct parameters are in place in addition to recreating how the symbol looks (correct line weights and text size).  Now it needs to be in the project and one must take care that the tag is assigned to the correct model category.  All of these steps are simple, but it takes time to be built into the Revit MEP template.

The second part of standards focuses on the 3D modeling content within Revit MEP.  This includes having a well-defined library for MEP families and having custom view templates.  Having a library of your “cookie-cutter” families is necessary.  Downloading different manufacturers’ basic equipment on every new project wastes time.  A great example is a standard lay-in air device, which is very common on every project and doesn’t vary (physically) from one manufacturer to the next.  Major equipment such as chillers and air handling units are examples of equipment you should still choose to model custom for that project.  Having a good BIM support team can be a great aid in helping this last key ingredient.  This way engineers are more focused on engineering instead of learning how to make Revit families or creating complex filters for piping systems.

Grading Your Efficiency

Now that we have the three key ingredients for a strong Revit MEP user, does this confirm how you judge your own competence?  Or maybe you just realized how to help a fellow MEP engineer become less frustrated. Here are six different examples of Revit MEP users.  Use these examples to help measure your own efficiency.  Here, I measured efficiency in two different ways: percent under or over budget, and the amount of LOD the user puts into the model.  The most efficient users could reach a LOD 300, while using less than 100 percent of their allotted budget.

User A (The Naive): First-year Revit user. Wants the same level of detail as the “old” AutoCAD ways because it’s “faster.”  Has good 2D standards, but lacks 3D content and no view templates because there is no BIM support team.

User B (The Apprentice): First-year Revit user.  Understands there needs to be some thought of how ducts and pipes should be installed in a plenum.  Has good 2D standards and the company has a good BIM support group.

User C (The Daring): Two years of Revit experience.  The user now knows the basic potential of Revit MEP, so he/she wants to model every single pipe elbow and download the exact floor drain by manufacturer.  Has good 2D standards and the company has a good BIM support group.

User D (The Over-Modeler): Four years of Revit experience.  The user now knows the full potential of Revit MEP, so he/she wants to calculate velocity through ductwork and also calculate air pressure drop, which requires complex duct/pipe connections to all equipment and requires many workarounds.  Has good 2D standards and the company has a good BIM support group.

User E (The Realist): Two to five years of Revit experience.  The user now knows the full potential of Revit MEP, but is also realistic that he/she doesn’t need to model every single pipe elbow or use a 5mb floor drain family, but still models enough to avoid field coordination problems.  Has good 2D standards and the company has a good BIM support group.

User F (The Unequipped): Two to five years of Revit experience.  The user now knows the full potential of Revit MEP, but is also realistic that he/she doesn’t need to model every single pipe elbow or use a 5mb floor drain family, but still models enough to avoid field coordination problems.  There is no MEP content creation, along with no company standard template.

How Can We Be More Efficient?

It doesn’t matter if you’re still transitioning into Revit MEP, you’re already a veteran if you’re a contractor or a design engineer. The question has been asked, “How can we be more efficient while still using Revit?”  There are several major upsides to using BIM, but now we need to achieve those upsides faster than how we used to draft in 2D.  The prerequisite to user efficiency is to clean up any hardware or networking issues, which can very quickly drag down your productivity.  Now you realize that just increasing your Revit MEP knowledge doesn’t solve the entire question.  Knowledge, LOD, and Standards are the three key ingredients that will take your efficiency to new heights.

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About the Authors

Ben P

Ben Pielhop is a mechanical engineer for Dewberry, a national firm that provides engineering and architectural services.  His role also includes being the Revit subject matter expert for mechanical and plumbing.  Ben started using Revit in 2009, and graduated from Milwaukee School of Engineering in 2010 with a B.S. in Architectural Engineering.

 

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