Revit MEP: What MEP Needs from Your Architectural Model

Collaborating with various disciplines, both internally and externally, is an essential aspect of project success. As an architect, it is imperative to ensure that your actions are supporting the efforts of other teams, particularly MEP, to minimize the need for rework. In this article, we will explore how the architectural and structural aspects of a project impact critical workflow processes and provide insights on how to optimize collaboration with these teams for greater project efficiency.

Our Basic Design Workflow

After the contract is awarded, we initiate our basic design workflow, which consists of four main phases: schematic design, design development, construction documentation, and construction administration. In each phase, we work closely with our client and other disciplines to ensure that the design meets the project requirements, budget, and schedule. We also use various tools and techniques, such as BIM, clash detection, and energy analysis, to enhance the quality and efficiency of our design process. If I were to list out our basic process which can vary from firm to firm, it would look like below.

  • Proposal Acceptance/Contract Awarded
  • Project Kick-off Meeting
    • Our project kick-off meeting consists of our project team and our client, whether they are internal or external.
  • Project Setup
    • When I set up a project, I typically will use the Architect’s model using their title block, matching their view naming, view placement on sheets, sheet numbering and naming.
  • Internal BIM Kick-off Meeting
    • The internal BIM project kickoff is where we discuss project needs and how the project was set up.
  • Our Design Process Starts
    • During the life of the project, our design will probably change 3-4 times or more.

The Importance of Kick-off Meetings

Kick-off meetings are when the project collaboration really begins, and you may be meeting the rest of the team for the very first time at this meeting. There are plenty of important project related topics that should be discussed during the project kick-off meeting.

BIM Execution Plan (BEP/BXP)

Even after all these years, companies and subsequently a lot of projects are still not issuing a BIM Execution Plan. Why is that? Is it because they don’t have time to develop one? Do they think they are not necessary? I am sure if you ask someone from any firm, you will get a myriad of different reasons as to why or why not for their use. If you are not using one for projects, what are your reasons? Without getting into specifics, because I assume those that are attending, already know what a BEP/BXP is already. If there is no BXP, when there is no BXP present for the project, here are some of our more crucial topics to discuss.

Level of Detail

In my experience working at various companies the past 17 years that utilized Revit, most families developed were in the LOD 200-300 range. While they may visually resemble LOD 200 pumps, the model and family information included corresponded to LOD 300-350.

In the context of an MEP (Mechanical, Electrical, and Plumbing) Revit model, design intent refers to the underlying concept or idea that guides the creation and development of the model. It is the intention of the designer, engineer, or architect to convey their vision and objectives for the system that will be built, installed or modified in a building.

While we could accurately model the spatial location of our piping, it would be challenging for anyone, particularly the contractor, to discern what was depicted on the sheet. Electrical drawings, on the other hand, are largely diagrammatic in nature. Due to this, most electrical families contain nested annotations as it is difficult to determine the modelled elements in a plan view. Despite providing a 3D model, our deliverables still consist predominantly of 2D representations of the design. Ultimately, our design approach prioritizes simplicity, clarity, and ease of interpretation for contractors, municipalities, and owners, while taking into consideration time and budget constraints.

In summary, design intent is an important concept in MEP Revit modelling that helps to ensure that the resulting system is efficient, effective and meets the needs of the client and building occupants.

Model Coordination

Is Model Coordination required for the project either using BIM 360/ACC, Navisworks, or some other third party coordination software? Autodesk Construction Cloud Model Coordination is great for Design Coordination whereas Navisworks is great for Constructability Coordination. Even if some level of model coordination is not required for the project, I firmly believe it is important for all parties involved to do their due diligence to ensure their design is spatially coordinated. More on that later. For MEP, this should be the norm. Lighting Fixtures should not sit in the same ceiling tile as an Air Terminal, pipe shouldn’t be running through Duct, etc, etc.

End Use of Model Considerations

  • Visualization/VR/AR
    • Enscape
    • Twinmotion
    • Workshop XR (formerly The Wild)

  • Does the owner want the models?
    • If so, what will they be doing with it?
  • Digital Twin?
  • Is the General Contractor getting the models?

While owners may get the model as a deliverable, most of them do not have the capability to open them. Contractors, as I will discuss a little later, will probably redo the MEP model in their go to fabrication software. In the past I have done full 3D coordination in Revit that was quite the headache.

About 12 years ago there was a company in Denver called BIMShift that had a program called DataGate that would let you upload a Revit model to their website for model coordination and facilities asset management. It was very short lived, and they have since gone defunct. Interesting concept at the time when digital twin wasn’t even a thing yet.

Digital Twin is a fairly new industry trend that I have not found a good for it yet. Autodesk has Tandem now but I unfortunately have not been keeping up with it. When I first saw Tandem, I immediately thought of that DataGate tool I mentioned above.

Challenges with Revit and Fab Programs

Fabrication software is few and far between. There are some that are Revit add-ins and some that are independent programs. The two main programs are Revit and Fabrication CADmep and neither of these tools do not have very good interoperability without extensive and problematic parts mapping.

Other programs or tools include:

  • Trimble Sysque
  • AutoPipe
  • AutoCAD MEP

The Fabrication Parts in Revit, have little to be desired. Both programs need to be installed for that interoperability to happen. Configurations need to be created in CADmep and loaded into Revit and those configurations mapped to Revit Fab parts.

I have a concern regarding Revit Fabrication, as I am unaware of anyone currently using it. However, given the considerable amount of time and effort that Autodesk has spent, it is probable that there are users. Nevertheless, it is worth mentioning that Revit does not seamlessly integrate with the spooling software commonly utilized by contractors for duct and pipe fabrication.

Typically, before commencing construction, general contractors and their subcontractors tend to recreate our MEP (mechanical, electrical, and plumbing) models using software compatible with their specific cutting machinery.

Furthermore, the intricate level of detail required for fabrication is often impractical within project budgets.

So, What Does MEP Need Afterall?

I have already talked a lot about the importance of Kick-off meetings but what about the modelling needs of MEP, the name of this session you ask? The reason I started with importance of Kick-off meetings is that the needs I am going to discuss could be outlined in a BIM Execution Plan or at the very least discussed during the Project Kick-off meeting so that expectations are at the forefront of the communication and collaboration. These needs could be construed as wants by some, but either way they help ensure our design intent and really go hand in hand with each other.

Building Envelope

The building envelope is crucial to MEP (Mechanical, Electrical, and Plumbing) engineers for several reasons. The building envelope refers to the physical separation between the interior and exterior environments of a building, including its walls, roof, windows, doors, insulation, and other components. Here's why it's important to MEP engineers:

1.    Thermal Performance: The building envelope plays a significant role in the energy efficiency and thermal performance of a building. MEP engineers need to consider heat gain, heat loss, and insulation properties of the envelope to design appropriate heating, ventilation, and air conditioning (HVAC) systems. By understanding the envelope's thermal characteristics, they can optimize HVAC system sizing, select appropriate insulation materials, and minimize energy consumption.

2.    Indoor Air Quality: The building envelope influences the ventilation and air quality within a building. MEP engineers must ensure that the envelope allows for proper air exchange while preventing the infiltration of outdoor pollutants. They consider factors such as air sealing, air barrier systems, and ventilation strategies to maintain a healthy and comfortable indoor environment.

3.    Moisture Control: Managing moisture is crucial to prevent issues like mold growth, degradation of building materials, and compromised indoor air quality. The building envelope must effectively manage moisture infiltration and condensation. MEP engineers work closely with architects and building envelope specialists to design moisture control systems, such as vapor barriers, waterproofing, and drainage systems.

4.    Structural Integrity: The building envelope provides structural support and protection against environmental forces such as wind, snow, and seismic activity. MEP engineers need to understand the envelope's structural characteristics to properly integrate MEP systems into the building's design. They coordinate with structural engineers to ensure that MEP system installations do not compromise the integrity of the building envelope.

5.    Integration of MEP Systems: MEP engineers must coordinate the installation and integration of various mechanical, electrical, and plumbing systems within the building envelope. The envelope affects the routing and distribution of MEP systems, including ductwork, piping, conduits, and electrical wiring. By understanding the envelope's layout and constraints, MEP engineers can optimize system designs, minimize spatial conflicts, and ensure efficient operation.

Overall, the building envelope is a critical consideration for MEP engineers as it directly influences energy efficiency, indoor air quality, moisture control, structural integrity, and integration of MEP systems within a building. By accounting for these factors, MEP engineers can design sustainable, comfortable, and efficient buildings.

Accurate Geometry

When it comes to Heating/Cooling Loads, Energy Modelling or Lighting Analysis, complex geometry from a detailed messy architectural model can be a huge pain point.

Simple accurate geometry is best with the correct U values so that when things are exported to GBXML, the engineer won't have to manually re-enter most of the necessary info in the Loads program.

While MEP can be diagrammatic or design intent, Architectural and even Structural models need to be dimensionally accurate. While fractional dimensions are used, tolerances of less than a 1/8th or maybe even a 1/16th is about what can be measured, however, in Revit, tolerances should be set to 1/256” so that those smaller dimensions can be caught and addressed, especially if someone nudges something. You don’t want your building to be say a foot longer than it should be because the dimensions said one thing but actually measured something else.

Spatial Coordination

MEP engineers need to ensure that their systems fit within the building. This means is there enough ceiling space to run the necessary duct mains and as well as sloped sanitary piping? An Engineer should review the Architectural plans and sections to see what space they have to work with and if there is not enough room, coordinate with you as the architect to figure out a solution. This can be an issue when an Architect wants ceilings as high as possible but does not leave enough room below any structure and above the ceiling. The more turns or transitions up/down a duct has increases the amount of pressure drop, thus decreasing the amount CFM being pushed. This could in turn cause equipment to overwork themselves to compensate for another equipment's inefficiencies.


Room information is used to create our MEP spaces. Rooms and Spaces are independent components used for different purposes. Spaces are exclusively used for the MEP disciplines for analysis of MEP Systems and can be grouped together to create HVAC Zones.

I am sure most, if not all, know that rooms are phase specific, so when it comes to Renovation projects, those existing rooms need to be defined in the existing phase as well. If the project has Units in say a multi-family or hospitality type project, we really do not need to know where the kitchen or bathroom is, we just need to know the name of the unit.

I recently started using the Room Name/Number in my space tags, so they automatically update instead of manually using the space naming utility.

Structural Information

If there are no structural models, the architectural model should include information on the structural components of the building, including any structural beams or columns that may impact the design of MEP systems. You know, typical things we cannot run our duct, pipe, conduit or cable tray through.

We cannot stress enough for the need of better on-going communication. Any changes to your model that will affect our design should be communicated. Please do not assume we will see those changes if we are not looking for them.

Decisions That Affect Us!

Changes can, especially those without proper communication, can have a huge ripple effect to what we do or have done.


I am not here to debate hosted vs non-hosted. They each have their pros and cons, but I am firmly in the Hosted camp. Most of our MEPF families are face hosted and we need a host to exist in the Architectural model. If ceilings are present, we need those before placing our ceiling mounted families Lighting Fixtures or Air Terminals. Sure, we can use Ref Planes, but moving them from the Ref plane to the ceiling when they are modelled is quite the chore. Because of that, we typically wait until they are modelled, which could be quite late in the design process.

As a BIM Manager, I want to know when something needs my attention, whether that is an orphaned family, or something needs coordination review.

Orphaned elements are way better than deleted elements like from the pre 2012 versions of Revit MEP. We ask that you minimize the deletion of your walls or ceilings so you can redo them using a different type. We would prefer that you modify them or change their type so that their GUID does not change which is what causes our families to be orphaned.

Something that can affect our hosted elements is when the position/orientation of your model changes. I am dealing with a project now that is halfway through design and the Civil team, and the client decided to change the rotation of the building on the site as well as move several of the outbuildings. The architect wants to continue as if nothing has changed but our MEP Site plan will be completely incorrect and will need some major workarounds to “look” correct. On the flip side of that, if a model changes its orientation, elevation or position on the site and that is not communicated, it can have adverse effects on our models. A change in the PBP or SP can be an easy change before their model is updated bit not so much with live linking though.

Copy/Monitored Elements

  • When grids change, sometimes it can be easy and other times it is so painfully time consuming that it is better to just delete them all and copy them again when it comes to renumbering them. In doing so could affect other things like any offset grid heads that are no longer offset when recopied.

  • Hopefully levels are set when MEP starts their design. Changing a few inches or feet here and there, while can cause ducts or pipes to move up into each other is not that detrimental. However, moving levels several hundred or thousand feet without prior knowledge can break MEP systems.

  • While we can copy/monitor things like Lighting Fixtures and Plumbing Fixtures into our models, they more than likely do not have the necessary parameters for our schedules, tags or match our company standards. We can copy and replace with our own families but that only works if your families and our families have the same origin point.

Phases and Phase Filters

How many of you deviate from the Phases and Phase Filters that Revit provides?

Going back to a BIM Execution Plan or at least the Project Kick-off meeting, a simple list of what you are using would go a long way with consultants to be able to know that up front. When a model is loaded into a project and these do not match, the views will not display things correctly. Each one of those view templates, which at my last firm was about 140, would have had to be edited one at a time to correct that information. Early in my path to BIM Management, I was burned bad when I was creating a few projects where those did not match. I spent so much time changing those in each view template that I now look for that information in my review of the Architect’s model before my Project Setup begins.


It really does not matter to us whether the furniture is in 3D or 2D, what matters to us is whether we can see it. When it comes to showing furniture on the Lighting RCPs, if furniture is 2D, it stills needs to be elevated so that it fits within our view range. Our RCP view range is set to have a 1’-6” cut plane so that we can see modelled furniture in our RCP views for fixture placement and would need 2D furniture at the same elevation.

Linked Files vs Groups

Aaron Maller is a huge proponent of Groups regardless of project size. He was on an episode of BIM After Dark with The Revit Kid about two years ago discussing the pros and cons of Links and Groups. Go watch it if you have not already.

While I also would prefer the Architect to use Groups. However, if the project is small with just a few links, it is quite manageable but when you get 40+ linked models with 400+ instances of those links, that is not manageable. I worked on a project in Denver several years back where this was the case. It took 20+ minutes to just open the project and doing anything was a waiting game. We asked the Architect to utilize groups, but they refused. We drastically limited our updates to once every 3 months instead of every 2 weeks. When we got a model, I would spend 8-12 hours converting every one of those links to groups, even if they broke. I would get casework at the wrong elevation, duplicates of things, et cetera, et cetera, but the result allowed us to finish the project within our deadlines. With that said the sheer quantity of links and their instances matter for MEP models when those models need to be attached so we are not manually linking all those models and their instances.

Last Minute Architectural Changes

We all know changes will happen and projects will most likely get Value Engineered. With the Autodesk Construction Cloud platform, a lot of projects use the “Live” linking method and MEP loses all control when it comes to getting Architectural Model changes. Now they just happen.

Architects will continue to work up until a deadline we all have. When changes happen at the last minute, there is no time react, things could be broken, out of place or files could get corrupted because one person does not have those changes.

Bottom line, our MEP engineers, designers or even I as the BIM Manager need to be given ample time to react to any changes that occur during the design process. At a previous firm, our contract stated 7 business from last update but often we were able to accommodate 3 business days. Everyone can easily get burnt out chasing those changes and tight deadlines.

Final Thoughts

Ultimately, we are all just pieces of a puzzle and if we have all the right pieces, we will create a beautiful and functional building.

Our Buildings Group at Garver just recently attended a group Summit and the last activity of our first day was a team building exercise. Each table received a box with a picture of a project we designed that had puzzle pieces inside. While putting the puzzle together several of the groups found themselves, my table included, forcing the pieces together because they looked almost identical, but a few areas were off. Eventually we got it worked out but if you try to force something, most of the time, it just does not work.

When everything is all said and done, at the end of the day, we truly do this to build relationships with our clients and the satisfaction of designing something meaningful and getting paid is a nice bonus. I work with numerous engineers who are good friends with Architects that they met working on a project together. My kid's godfather is an old co-worker of mine. Don’t sit at desk behind computer screens, get out there, have face to face meetings during and after work hours to help build those relationships and friendships while strengthening them as well.

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