fine-tune your model performance in autodesk revit...

Fine-Tune Your Model Performance in Autodesk® Revit® MEP

Speakers: Teri Wagner and Darryl McClelland

MP4582 Models running slow? In this class, we will take a look at some performance enhancing tips to make your models open, save, and perform faster. We will also talk about what can be discussed with your architectural partners before anything gets modeled in Revit.

Learning Objectives At the end of this class, you will be able to:

• Explain what is involved with managing models in Revit® MEP

• List topics that can be discussed with your architectural partners before starting a project in Revit®

• Create “lite” versions of architectural models for linking

• Effectively use worksets and review, find, and resolve review warnings

About the Speakers

Teri Wagner, BIM Coordinator, Heapy Engineering Teri has 17 years of experience in the

architectural, mechanical, electrical, and plumbing industry. Armed with her knowledge base of various

Autodesk® products she transitioned to the world of Building Information Modeling (BIM) five years ago.

Teri has been instrumental with standard and workflow process creation and documentation and the

overall enforcement of the same. She manages some of the most complicated and complex project

models at Heapy Engineering.

[email protected]

Darryl McClelland, LEED AP BD + C, BIM and Virtual Design Manager / Project

Coordinator, Heapy Engineering Darryl is a graduate of Purdue University and has over 26 years of

practical design experience in the mechanical, electrical, and plumbing industry. Although his primary

focus is the design of mechanical systems, he has designed electrical and plumbing systems as well. He

also owned his own engineering business for eight years. His design experience ranges from complex

research laboratories and institutional facilities to medical and professional office buildings, and

everything in between. He is an active member of ASHRAE and ASPE. He currently oversees and helps

integrate the BIM process into all Heapy Engineering projects.

Fine-Tune your Model Performance in Autodesk Revit MEP

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What is involved with managing models in Revit® MEP Managing models and keeping them running smoothly is one of the most important aspects of a

project from the project profitability standpoint. Inefficient or underperforming models can drag

down the entire project team and quickly eat into your project profit.

Model management is a workflow process and is critical to your overall success. The exact

workflow process will vary from firm to firm and will be based on your firm’s size, projects,

company standards, etc. The model management workflow process evolves with every project

as each project has different constraints (i.e. team, external requirements, etc.).

Each new release of the Revit product will demand that you perform a thorough review of your

current workflow and model management processes and adjust those accordingly based on any

changes made to the product.

For example, prior to Revit 2010, if a user wanted to specify Worksets when they opened a

Revit project, they had to manually select the option in the Open dialog.

Based on changes in recent product releases, you might incorporate this functionality as part of

your Project Setup process to make this the default option for opening Revit projects. This will

force users to choose which Worksets to open/close before they open a project. This can have

a positive impact on the opening times of your Revit project models.

Project Setup

Determining how a Revit project should be setup can be based on the type of project and the

overall square footage of the project. Here is a rough guideline that helps us better understand

when we might need to split disciplines into separate models.

Based on data gathered from various different types and sizes of projects, we have developed a

rule of thumb calculation to help us determine the final size of the Revit file which in turn helps

us determine if we should begin breaking the model down even further. Our rule of thumb

calculator takes the overall square footage of a project and multiplies that by 2 to give us an

approximate file size. 87,000 square feet equals approximately 174 MB. This will give a rough

idea of what to expect at the completion of our Construction Documents. There are many

factors that can affect this number. A warehouse that is 100,000 square feet will result in

smaller file sizes than a hospital with the same square footage.

200MB is the magical number when it comes to file sizes in Revit. When your file exceeds 200

MB you will begin experiencing performance issues and delays.

Armed with this knowledge, we can interpolate when it will be beneficial for us to split our project

into separate discipline models. We have determined that it is best for us to use separate

discipline models when the project is 100,000 square feet. Your mileage may vary depending

on your hardware configuration, standards, etc.


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Space Naming Utility/Monitoring Room Changes

The Space Naming Utility should be run to address any errors between the architects room

names and numbers and the engineers Spaces. A visual inspection should occur to ensure all

areas have Spaces associated to them.

Matchlines

Unfortunately, you cannot Copy/Monitor matchlines. Therefore, you should include a view to

facilitate visual monitoring of changes made to matchlines.

Managing Links

It is recommended that Relative paths be used for all linked files. It is also recommended that

Reference Type for Revit links be set to Overlay. A cursory review of the model should be

made to ensure no imported links have been used.

Monitor Correct Workset Use

The larger the project, the more important this becomes. Just like layers in AutoCAD, if you are

modeling elements on the wrong workset, you can cause visibility and performance issues. In

addition, this can affect exporting to NavisWorks. Correct workset usage is important as

elements placed on the wrong workset can show up as associated with the wrong discipline

during specific clash batches.

Monitoring View Use

Delete un-used extraneous views. Workflow processes can include any uncategorized and

unnamed views will be deleted during a project update. This helps to keep the Project Browser

clean and easier to navigate for anyone new coming into the project.

Project Updates

What has changed with the architect’s file? Copy/Monitor shows items that have been changed

that were monitored. It does not show when something new has been added to the project.

Therefore, it is necessary to visually verify if any new columns, levels, etc., have been added to

the project model. This is easy to do for a small project but the bigger the project the more

difficult it becomes to find new items that need monitoring. It’s important to stress to the project

team to document changes and additions that may affect project workflows.

Can you find the new levels in this view?


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Coordination Review

When you receive an updated model, Copy/Monitor items that have been changed in the source

file will require a coordination review. It’s important for the model manager to take care of all

coordination reviews. It would be unwise to arbitrarily accept level changes the day before a

submittal. It might be best to make notes regarding level changes and then issue that

information to the project team. From there, all warnings that occur with the level changes can

be documented and forward to the project team.

Who should be taking care of all of this?

Revit and the BIM process are still fairly new to some as compared to AutoCAD. Some might

recall the days of working for firms with little to no CAD standards and the chaos that ensued

from everyone doing what they thought was right. The same happens for Revit and the BIM

process. There are a lot of variations to product usage. It’s important to establish BIM

standards and select a few key individuals that can be counted on to follow/enforce these

standards.

Project teams should consider establishing a model manager role to handle any and all model

management tasks for the team. This role can help standardize a large portion of the Revit and

BIM process and help the end users feel more comfortable going from team to team and project

to project no to mention a more standardized and uniform way that your company’s projects are

set-up.


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Topics That Can be Discussed with Your Architectural Partners Before

Starting a Project in Revit® There is no doubt about it, BIM requires communication. Models created today are more

complex than the simple 2D AutoCAD drawings. What one person on the project team does, or

does not do, can have significant impact on others. The question is do they fully understand

that? It is better to err on the side of over-communicating rather than not communicating at all.

In the ongoing effort to educate and help others understand your needs the development of a

simple discussion checklist is beneficial to all project team members. This will help facilitate

communication amongst the team. Depending on the size of the project, project managers

should be encouraged to arrange a kick-off meeting not to review the project but to review the

technology for the project and approach behind that.

The earlier this discussion takes place the better off the project team will be. The checklist that

is developed should never be considered finished and should always be viewed as a living

document.

Project Expectations

Before you begin any project, the entire project team needs to meet as a group to establish the

overall expectations for your project. As a group you should identify anything that will help

define those expectations as well. For example, are you working with a client who has created

or established BIM Standards to be met for their projects or perhaps you are simply using the

BIM process to better coordinate your project. Whatever the reason, it is important to establish

those expectations at the very beginning of the project and it is even more critical to the overall

success to the entire project team that everyone is held accountable to meet those

expectations.

Product Version

This can appear to be a given. However, looks can sometimes be deceiving.

For example, the project team starts a project today. Revit 2012 is the latest product currently

available to users today. However, Revit 2013 is only a few months away from being released.

Does the project team start in 2012 and upgrade to 2013 or does the project team decide to go

a different route to create project documents before the 2013 product is available?

Now, factor in project duration and this becomes an increasingly challenging question. The

same project under discussion will not have Construction Documents completed for two years

and it will take three years to build the project. That is a total of 5 years and a lot can change in

products in the course of 5 years. The project team needs to decide as a group if the project

will be upgraded to a newer product version and if so when and how many times?


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Please keep in mind that upgrading to a newer product release can be very detrimental to a

project.

For example, based on the functionality changes from 2010 to 2011 upgrading your project

could cause issues that relate to your panel schedules. For example, when upgrading a default

panel schedule template will be applied to your panel schedules. That might cause circuits to

be dropped if a 42 slot template is set to default and you have a 60 slot panel in your project.

This will cause 18 circuits to be dropped thus requiring you to re-circuit a portion of your project.

Other issues include distribution/circuit breaker schedules that might have 2 spaces between

each circuit. This will cause you to go through and move each circuit up to remove the

"spaces".

This is only one aspect of upgrading a project and this comes at a high cost to project

profitability since you are redoing work that you would not have had to otherwise do.

If it absolutely critical for your projects success to upgrade to a newer product release you will

need to choose a logical time to do so and fully understand what items will need to be

addressed after the upgrade and the cost impacts of the upgrade.

The Golden Rule to live by in regards to product upgrades is that things will break. You may not

see what breaks but it will happen and it will become the silent killer in your model.

The Pros and Cons of a Single Model vs. Multiple Models

To split the model or not to split the model… that is the question. This is a challenging question

if your project falls within that grey area of performance.

For example, a true BIM process would have everything residing in one model. That might be

practical for small projects that are completed under one roof but that might not be practical for

project teams separated by distance and different fire walls. Even if certain aspects of a project

can be done in one model under one roof it is always best to review this based on work sharing

issues that might occur. Regardless of the direction you choose to go, thought must always be

given to this topic for every project.

What sheet size will be used for the project, 24x36, 30x42, or 36x48? Believe it or not this can

impact the model break point locations on large projects.

Ceilings

Ceilings can be an important component to every project. Depending on the engineers

workflow process ceilings may take on a completely different persona to the engineer.

For example, when a Space in placed in a model and the ceiling has been set to room bounding

the Space will stop at the ceiling. This means that the plenum space is not accounted for. To

include the plenum space in the engineer’s calculation the engineer will need to place a Space


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for each plenum space. Although this can be done, there might be an easier solution that does

not cut into the projects profitability as much.

Open dialog with the architect to determine if the architect can set there ceilings to be non-room

bounding. This will allow the Spaces to go from top of floor slab to underside of floor slab. This

might be more beneficial to the engineer depending on their overall workflow and calculation

processes.

Model Groups

Model Groups can be used to represent repeating layouts or layouts that are common to many

building projects. Floors in Model Groups should not be Room Bounding.

Phasing

If phases are going to be used during the project it is important that the entire project team be

made aware of this.

Shared Coordinates

Project coordinates can wreak havoc with a project especially if the coordinates are changed

after initial setup has completed. If this occurs, the entire project team should be notified

immediately. This is especially critical for project rotation. If the project team utilizes multiple

site models, it is important to know which model to acquire the shared coordinates from. There

should only be defined site for each project.

Copy/Monitor

What gets monitored? This is another great question to ask as part of your model management

process. Typically, as part of our standard, we only monitor levels and grids. This is primarily

due in part to the issues that arise with monitoring other elements. The more items you monitor

the more data points Revit tracks and the more data points that Revit tracks the more your

model performance is affected.

Let’s say that a project decision has been made to monitor the light fixtures contained within the

architect’s model. If the architect decides to delete light fixtures rather than change the fixture

type, this will cause disconnect issues and loss of work for the electrical team.

It is important to discuss an item like Copy/Monitor with the project team so you can avoid

issues like the one described above. Communication is extremely important in the BIM process.

Hosted vs. Non-Hosted

In some aspects, this is a similar conversation to the Copy/Monitor dialog.

If the entire project team is working in a single model hosted items can be an effective solution

to addressing changes. However, to be an effective solution, ground rules must be set up front

and strictly adhered to or there will be failure.


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Let’s say that a project decision has been made to use hosted items. An electrical designer

places a hosted panelboard on a wall that the architect has placed. If the architect decides to

move the wall the hosted item will move with the wall. However, if the architect decides to

completely change the configuration of the wall that has the hosted object on it and deletes the

wall all together and draws a new wall the hosted item has a 50/50 chance of automatically

getting deleted because the object that it was hosted to no longer exists. In the case of a

panelboard getting deleted, all circuits will need to be re-created.

Unfortunately, the majority of the OOB families are hosted. If you want to use primarily non-

hosted families, a lot of new families will need to be created since there isn’t a toggle to flip

between hosted or non-hosted. Also, some families require hosting in order to display properly,

i.e. floor drains in a sloped floor or lights in a sloped ceiling. It is important to determine if the

project team will use hosted or non-hosted items in the project. Communication is extremely

important in the BIM process.

Review Warnings

If your Check Oil warning light comes on in your car do you drive another 5,000 miles before

you address it? Typically, one would address this issue as quickly as possible in order to avoid

long term damages to your engine. Warnings in Revit should be handled in the same manner in

an effort to help you avoid long term performance issues with your model.

It is recommended that you monitor and report Warnings to project team when those Warnings

exceed an acceptable amount in relation to severity of warnings present in the model. Every

effort should be given to assist the project team to help find and resolve Warnings.

Remember, the more Warnings that you have the more Warnings that Revit has to track and the

more Warnings that Revit has to track the more your model performance is affected.

Design Options

Design Options should be eliminated once the project team enters the Construction Document

phase. It should be noted that Spaces and MEP Systems do not work as designed with Design

Options. If Design Options are used, the project team will need to be given detailed information

about the nature of the options and when they will be accepted or rejected.


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Create “lite” Versions of Architectural Models for Linking After receiving and updated or new project model a typical workflow could be:

Detach File and Open Purge Save the file into the project directory with the correct name,

overwriting the previous version as necessary Re-establish necessary links Synchronize

& Relinquish worksets.

This works fine for small and medium-sized projects. However, what happens when the

architect sends a 625MB interiors model? Purging might take that file size down a considerable

amount but what if it still exceeds that 200MB threshold as previously discussed?

Creating a ‘lite’ version of the architectural model(s) isn’t necessary for every project. Typically,

it’s best suited for files that exceed the 200MB threshold after purging. Depending on the size

of the project, creating a ‘lite’ version of the architect’s model has the potential to make the file

smaller thus taking less time to load and less memory used.

In one particular case, there were only two architectural files for a 14 story hotel and convention

center. A core and shell model and an interiors model. The interiors model was 281MB after

purging. Creating a ‘lite’ version of this particular file reduced the overall file size to 183 MB.

Which would you rather link into your project?

Everything Must Go!

What does it take to make a ‘lite’ file? This depends on the type of project and the needs of the

project team. If the team is using Linked Views then it will be imperative to retain those views.

Otherwise, it is open season! If you wanted to you could delete every sheet, legend, schedule

and view in the project browser. Remember that aforementioned items are simply data points in

the model, sometimes a duplication of data points. Deleting those items can have a streamlined

effect on your models performance. It is recommended that you leave the default 3D View in

case you need to export your model to NavisWorks. It is also recommended that you leave a

simple Drafting View as your “Starting View”.

Occasionally, you might run into the following error: This action has caused the deletion of non-

editable Workset ‘View “ xxxx “’.


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Although there is the option to select Make Elements Editable that functionality does not

necessarily perform when you want it too. If you do receive this dialog, you should note of the

name of the view(s) and exclude them from your selection. This type of warning can also

happen when you purge your file. Make sure to note the items that are causing the error and

forward the information to the project team. These items could possibly contain corrupt

elements that could impact your models performance.


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Effectively Use Worksets and Review, Find, and Resolve Review

Warnings Up to this point we have covered a lot of items that can affect your model’s performance. Can

we stop here? We could but we would still be leaving a lot on the table. There are even more

items that can affect your models performance outside of the ones mentioned above.

Worksets

As mentioned earlier, the larger the project, the more important proper use of worksets

becomes. Guidelines need to be established on typical workset naming and use for large and

small projects.

Start with a basic set of worksets that will work well for small projects and then expand on the

naming and use for larger, more complex projects.

• *Shared Levels and Grids – I like to include an asterix preceding the name for this so that it will be ordered to the top of the workset list.

• E – Lighting

• E – Power

• E – Technology

• M – HVAC

• M – Plumbing

• xCAD - Links

• xRVT – Arch-Link

• xRVT – Struct-Link

From this basic list it is possible to then add designators for different levels, discipline specific

items, etc. Even with the additional designators added to the list, the uniform naming is familiar

and easy for users to adjust to. In the list below, XX can designate level or area. Optional text

can be added to the end to further identify specific use as in the case of splitting HVAC into

Ductwork and Piping.

• *Shared Levels and Grids – I like to include an asterix preceding the name for this so that it will be ordered to the top of the workset list.

• E – XX – Lighting

• E – XX – Power


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• E – XX – Technology

• M – XX – Fire Protection

• M – XX – HVAC – Ductwork

• M – XX – HVAC – Piping

• M – XX – Plumbing

• xCAD - Links

• xRVT – Arch-Link-COSH

• xRVT – Arch-Link-Interior

• xRVT – Struct-Link

Here’s a rule of thumb to keep in mind for worksets that get created based on levels or areas.

Encourage users to place duct or pipe that spans multiple levels and areas on the workset

associated with the level or area from which it originates. For example; ducts originating from an

air handling unit on the roof belong on the workset associated with the roof.

This can take some getting used to, but can become extremely helpful when maintaining

multiple disciplines in one file. I prefer to add the worksets dropdown to my QAT in addition to

the one shown in the status bar. This makes it twice as hard to miss what is the currently active

workset while performing modeling tasks.

Once a DWG file always a DWG file

For years DWG files have been a way of life so why reinvent the wheel if you don’t have to?

When you are using Revit it will be better for you to reinvent the wheel in regards to those DWG

files.

Regardless of how “clean” you think your DWG files are Revit will always view them as a “dirty”

intruder.

To optimize your model performance it is highly recommended that you minimize the total

number of DWG files in your Revit file. The more DWG files that you have the higher the

probability will be that you will have performance issues with Revit.

Certainly there are steps that can be taken to minimize the impacts of the DWG file. One way is

to Link DWG files into Revit; do not import them. Another way is to create a Workset for your

DWG files and not load them when you open your project unless you need them loaded.

Finally, if you are using legacy DWG details you will just need to “bite the bullet” and realize that

you need to create Revit details because the performance gains that you receive over your


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duration of use of the Revit product will far surpass your investment cost to recreate those

details.

Placing CAD Links into a Separate RVT File for Linking

One problem with linking an AutoCAD detail into a Drafting view is that Revit will place the detail

on an internal non-editable workset associated with that drafting view. This will cause Revit to

load that link every time the project is opened. You can manually unload the detail, but that

become a time hassle especially when you print and you forgot to reload the 52 CAD details

that you unloaded.

If your company is against maintaining two separate detail libraries don’t despair as there is

another alternative available to you. You can create a separate Revit file that will contain all the

AutoCAD links for drafting views. This file can then be linked into its own workset and controlled

in regards to how it loads as with other Revit links. Drafting views can be created and shown

via the By Linked View option of Visibility Graphics.

The only issue to this is the duplication of drafting views. However, the Revit file that contains

the CAD details can have view names that represent the detail name. This means you can

create a Revit template file with these details already linked in and named appropriately. Users

can simply copy the AutoCAD details and Revit template file from the library and place them into

the appropriate Project Directory. It will be necessary to re-establish links to the new location,

but that’s a simple Reload From…in the manage links dialog.

Review Warnings

There are two types of warnings that occur within Revit, Error Messages and Warning

Messages. Error Messages are defined as preventing the current action from happening.

However, on occasion Revit will allow you to ignore them. Warning messages are defined as

requiring no action and can be ignored. For the purpose of this discussion, all Error Messages

and Warning Messages will be referred to as Warnings.

Just because the Warning says it can be ignored does not mean it should be ignored.

It is critical to review and address every Warning that occurs. Some Warnings are more critical

than others. However there is no definitive list that describes which Warnings are the most

critical. The best rule of thumb is to fix all warnings. It is always better to be safe than sorry.

Warnings can account for as much as 20% of the Revit project slowdowns. Every time a

command is completed, Revit goes through the entire Review Warning list to check if the

command that was just completed, fixed any of the warnings. The longer the list the longer it

takes Revit to go through the list.

To help illustrate the importance, below is a quote from Steve Stafford, the Revit Forum

Manager on AUGI and owner of http://revitoped.blogspot.com/.


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First a silly message from the Management

• Procedure Item: Review Warnings

• Steps: Review and FIX them!!

• Thank you, the mgmt!

More seriously, do focus on warnings that:

• Affect calculations, rooms/areas & wall/boundary errors

• Duplication (multiple elements in the same place)

• Affect documentation - Type Marks/Marks/tagging accuracy

A team needs to know they exist and why they are there. The quantity of them varies

wildly as a design evolves. If the team is aware and tracking them then they don't turn

into thousands of errors that negatively affect the project.

From: http://revitoped.blogspot.com/2011/01/review-warnings.html

How do I Find the Elements Involved in a Warning?

You can show the current list of Review Warnings associated with a project by:

Manage Tab Inquiry Panel Warnings button (tooltip says Review Warnings).

Revit will display a list of Review Warnings listed by heading. Expanding a heading will display

all Warnings associated with that type of Warning. Clicking the Warning will highlight the

affected items in the display area. If the element is not immediately visible in the display area,

click an element in a Warning and then click the Show button. Revit will search all views in the

project for that element.

If Revit is unable to find a good view, you can also manually select the item by its Element ID.

This is shown in the Review Warnings dialog with each element. To select an element by ID:

Manage Tab Inquiry Panel Element ID drop-down Select by ID and type in the Element

ID.

Who’s responsible for fixing review warnings?

The entire project team should be solely responsible for fixing the warnings associated with their

discipline. It becomes the model manager’s responsibility to keep an eye on the number and

severity of Review Warnings in a project and direct the project team as needed to get them

fixed.


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How many warnings is it ok to safely have?

There is no magical answer for this. This is entirely dependent on the size of the project and on

the severity of the warnings. 1,000 Type Mark warnings are less detrimental than 1,000 Not

Well Connected warnings. Even then, if it’s a small project, those 1,000 warnings may not even

register when it comes to model performance. The only hit the project is taking at that point is

inefficient modeling and poor representation of your company especially if you have to hand this

model over to a third party based on contractual obligations.

Can you tell what is wrong with this picture?