Lean Design with REVIT

Lean Design with Revit

A major issue that we constantly struggle with while working on projects is the file size of our models.  While this is mainly an issue on our larger projects, we can also benefit from a leaner file on small tenant projects.  The leaner the file, the less Revit has to process in the background, the faster the program responds to our commands.

Below are some tips on keeping your Revit file lean (note:  some of these tips can be found in our Quality of Documents Manual section 1.7)

• Warnings:  Revit provides us with warnings to let us know that we are doing something incorrectly.  While these are commonly ignored due to time constraints or lack of knowledge on how to resolve, these warnings should not be ignored.  If left unchecked for too long, the Revit model can amass upwards of 700, 800, or even 1000 warnings. These warnings can make the Revit model slow and cumbersome, because it keeps looking to see if the warnings have been fixed. The most common and easiest to fix warnings are related to room separation lines overlapping each other or walls and warnings saying that two items have the same type mark which should be able to be corrected by any Revit team member.  More complicated warnings like ramp slope, stair riser warnings, unenclosed rooms, etc. may require the assistance of your project BIM Coordinator or a member of the BIM Team.  Reach out for assistance if you are unsure how to correct your warnings, but DO NOT IGNORE them.
• Over complicated Elements:  While Revit is capable of modeling many complicated things and making them parametric, you most likely do not need to.  When in doubt, follow the famous KISS mantra, Keep It Simple Stupid.  In Revit, this would mean only model what you need, when you need it.  Also, be conscious of items that you download from Revit City or manufacturers, as these tend to be over complicated.  Remember the saying, you get what you pay for.  Since these elements are free, they are often not the ideal elements to bring into your project.  No elements downloaded from an outside source (Revit City, Autodesk Seek, etc.) should EVER be placed into your Revit model without review by the project's BIM coordinator.
• Unused Views:  Revit is very powerful when it comes to creating different types of views. This is great, however, an excessive amount of views—especially 3D perspective or isometric views—can weigh a model down. Once you're done using the section you cut to quickly check something, make sure to delete it. Try keeping the philosophy of "name it or delete it" when it comes to views to keep your model in check as you go. 
• Large or Complicated Sketch-Based Items:  This means roofs, floors, ceilings, filled regions, ramps, stairs and any other item that put you into pink lined sketch mode. Complicated sketches using a lot of splines require Revit to process more information. This doesn't mean we shouldn't design wild curvy ceilings, it just means we should keep an eye on how that ceiling is impacting the file. Consider modeling these items as families outside of the project.  Review with the BIM coordinator for advice / direction.
• Unused Families:  Don't be a hoarder when it comes to Revit families in your model. Keeping a small collection of items you are sure you'll need in the future is ok, but keeping every piece of casework you loaded just in case you need it someday is not. If a component you need accidentally gets purged, it can always be loaded back in. 
• Groups:  Groups always seem like a great idea at first, but they wind up functioning differently than you expect them to. Use groups sparingly and with good reason. If it seems like your group could be made into a static family, it probably should be. Also, be wary of the types of components you're grouping together. Wall hosted items like sinks or doors can have issues when they're grouped away from their host (the wall), or in with non-wall hosted items like sinks or casework. 
• Embedded CAD Files or Images:  This is a huge source of file size and model performance problems in Revit. If you absolutely must bring CAD into a Revit model, always save a copy of the file first and clean out the riff raff. Delete any elements that somehow snuck off into no man's land, purge the file, run the "overkill" command and audit it. Make sure when you type in "Z E" for zoom extents that your drawing is centered on the screen.  
• When you bring the CAD in, always link it instead of embedding it. That way, you can find the file when you need to modify it, reload it or remove it. Embedded CAD has the knack of getting lost in your views. Sometimes it can get hidden and become difficult to find. CAD files found to be embedded and not linked are subject to deletion by the BIM coordinator at any time.
• In-Place Families and Overloaded Hosts:  These should be used very sparingly, if at all. Modeling in an outside family is actually easier than using the family editor. Also, when you copy an in-place family, it makes another family. Before you know it you could have Special Casework 1 ,2, 3, ... 25.... Only use an in-place family if it's something you can't model outside of the project in the family editor. 
• Lengthy List of Design Options:  Once you are done using a design option, delete it. When there are a large amount of design options in the model, Revit has to think about how each option influences the objects around it. The more you have, the more thinking that occurs and the slower your model. 
• View Detail:  Do you have a lot of views that are using fine or medium detail level but have scales like 1/16", 1/8"=1'-0"? These views won't really show this level of detail for all elements effectively and you are asking the computer to show it anyway. 
• Saving to Central Using the Project Information Screen:  This is a simple legend view (previously presented) that will help your model open faster. Synchronizing with a 3D view open, especially one that has shadows on, will take a long time to open next time you want to access the file. Revit has a tool under the manage tab that allows you to designate which view you want Revit to open the file with. Your Open Save Page or another small view should be selected for this task).
• Auditing (Once or Twice a Week):  Checking this box will give you a warning that it will take a long time. However, I've never seen it take much longer than the usual load time. If you are ever having issues with your file crashing or behaving strangely, try auditing it and see if that helps. Often times it will. 
• Compacting the file at the end of the day:  It really isn't much slower than your normal save to central and can help keep your file trim and efficient. Confirm that you are the last person working in the file prior to compacting. 
• Over writing the model with a fresh copy:  This should be done by an experienced Revit user, preferably the Project BIM Coordinator, on an as needed basis. It will help clean up older back up and temp files, which will make the file size smaller. Review with BIM coordinator if you feel this should be done.

• Expedite Early Coordination by Inquiry within BIM:  As we have all experienced using REVIT, as the project progresses from Schematic Design through Construction Documents and Construction, the project file size grows exponentially.  Also, as you progress through the project, items begin to become attached to other objects, whether dimensionally or physically.  Based on these two issues, the process of coordination becomes imperative in helping to maintain and smaller and faster Revit file.  
• From early on in the project (starting in the early Design Development phase), we should be using Revit (and potentially Navisworks) to identify design elements that are either absent, poorly defined, inconsistently presented or uncoordinated with other elements.  Identifying these errors early on allows for errors to be more efficiently corrected, as the more complete a model becomes, the more complex relationships between elements become.  Addressing potential issues before these complex relationships are created, saves the user time in trying to correct the issue.  Also, it is common that more Revit warnings will be created during later phases of the project.  Adressing these coordination issues early on, can help in limiting the number of warnings created later on in the project, when file size severly begins to hamper production and speed.
• By querying these discrepancies or omissions with the relevant team member(s), the BIM Coordinator (or assigned team member) can prompt their resolution.  Some examples of questions that can come up early on are:
• Why is that revolving door in the middle of the walkway?
• How is that cantilever supported?
• Why do those walls extend through the roof?
• Where is the access to the maintenance space above the elevator?
• With  Revit, we have the ability to see these issues early on.  It is the teams job to keep asking the questions, until we get the answers, whether from a member of our team or a consultant.
• Propagate Design Fixity:  Once you have answers, commit them to the model.  Design fixity is a consensus on a design issue that enables the project to progress.  It is not "design freeze", but it does provide an agree basis for making and communicating decisions.  This decision making should be attained by phase review decision, which essentially means the cost of delay outweighs the benefit of delay.  While this exact moment should be the Project Manager's judgement call, the decision is informed by several factors, including the lead-time for the documentation phase.  We can design all we want, but at some point, the design team must commit to a decision or begin to lose money.
• The lack of design decision making and a delay in getting this decision into the model is probably the most significant hindrance to the economical success of a project.
• Prepare and Provide Early for Drawing Production:  The BIM Coordinator (or a designated team member) should set up the bulk of numbered sheets and implement consistent view templates in accordance with agreed drawing presentation standards long before a deadline looms.  This will ensure that, once the design is complete and coordinated, production information is delivered as quickly as possible.  The last-minute implementation of project-wide BIM standards and templates is to be avoided.