Revit likes RAM, and the more physical RAM it can use, the more model you can cache into active memory. Windows now offers several versions of a 64-bit OS. Windows XP, Windows Vista, and Windows 7 all have 64-bit capability. This allows you to bridge the 32-bit limit of Windows XP and earlier. The older operating systems were limited to only 2GB of RAM per application. A 64-bit OS allows you to use as much as you can pack into your machine.

If you have a 32-bit OS such as Windows XP, need to get your project done, and don't want to deal with the upgrade, use the 3GB switch. This setting allows you to grab an extra gigabyte of RAM from your computer for a maximum of 3GB. To take advantage of this switch, you'll need to load Windows XP Service Pack 2 and follow the instructions found on the Autodesk support site at www.autodesk.com/support; choose Revit Building from the menu, and read the support article on enabling the 3GB switch. Of course, you need more than 2GB of RAM in your workstation.

Before you email your IT department requesting 12GB of RAM, figure out how much you're actually going to use on your project. Your OS and other applications like Outlook will use some of your RAM, but you can calculate how much RAM Revit will need to work effectively. The formula is as follows:

There are two things you can do using views to help improve performance. First of all, the more views you open, the more information you will load into active RAM. Close windows you're not using to help minimize the drain on your resources. You can always close all the windows but your active one using the Close Hidden Windows tool. Choose the View tab and click the Close Hidden button (Figure B.1). It's easy to have many views open at once, even if you're concentrating on only a few views.

Figure B.1. Closing hidden windows

The other way to manage your views is to get rid of the ones you don't need. Revit allows you to make different views within your model quickly and easily. This can sometimes lead to having a lot of views (sometimes hundreds) that you aren't using in your document set and don't plan to use. Adding too many views can raise your overall file size even if you haven't added any geometry. Get rid of those unused views—typically views that are not on sheets—to help keep your file running smooth. We discuss how to create a schedule to help identify the unused views in Chapter 5, "Managing a Revit Project."

There are many times in a project process when you'll want to load content from another source as a background. This could be a client's CAD as-built drawings or a consultant's MEP design. You might link or import these files into your drawing and, during the busy course of the project, forget about them. As you've seen from the earlier tips on RAM use, all these small files add up. Getting rid of them can speed your file up and is simply just good housekeeping. If the file is linked, you can unlink it using the Link CAD button on the Insert tab. If they are inserted, right-click an instance of the file and choose Select All Instances from the context menu. Clicking Delete now will delete all the instances in the entire model as opposed to only the active view.

A CAD file, when imported into Revit, is a collection of objects that is managed as single entity. If you explode a CAD file, the single object immediately becomes many objects—and these all take up space in the file requiring more resources from Revit to track and coordinate.

If you're importing DWG files, leave them unexploded as much as possible. If you need to hide lines, use the Visibility/Graphic Overrides dialog box to turn layers on and off. Explode only when you need to change the imported geometry, and start with a partial explode to minimize the number of new entities. Figure B.2 shows the tools available in the Options Bar when you select an imported or linked DWG file. Also note that lines smaller than 132" are not retained with CAD files are exploded. This can result in unusable imports.

Figure B.2. Explode options

A better workflow than importing your CAD files directly into the project is to import them into a Revit family and then load that family into the project. This will also aid in keeping accidents from happening, like a novice user exploding Qathe files. This workflow is covered in more detail in Chapter 5.

Calculating the volumes on a large file can slow your model speed down immensely. These are typically turned on when exporting to gbXML, but sometimes teams forget to turn them back off again. Volumes will recalculate each time you edit a room, move a wall, or change any of the building geometry. Turn these off using the Area & Volume Computations dialog box found on the Room & Area panel on the Home tab (Figure B.3).

Figure B.3. Choose the area calculations to minimize unneeded computations.

Learn to manage the amount of information needed in a given view. Don't show more than you need to show in a view by working to minimize your view depth and level of detail. Here are some simple tips to keep your individual views working smoothly:

While it is possible to model to a very small level of detail, don't fall into the trap of overmodeling. Be smart about what you choose to model and how much detail you plan to show. If it's not conveying information about the project, maybe it's not really needed. The amount of information you do or do not model should be based on your project size and complexity, your timeframe, and your comfort level with the software.

When trying to decide how much detail to put into a model or even a family, there are three very good rules of thumb to help you make the right decision for the particular element you're looking to create.

Embedding user-defined constraints into families and the model help keep important information constant. However, if you don't need to lock a relationship, don't do it. Overconstraining the model can cause problems later in the project process when you want to move or modify locked elements. Constrain only when necessary. Otherwise, let the model be free.

While Revit has the ability to use geometry from several other file sources, use caution when doing so. Remember that everything you link into Revit takes up around 20 times the file size in your system's RAM. So, linking a 60MB NURBS-based ceiling design will equal 2GB of RAM and more than likely slow down your model. Deleting unused CAD files, using linking rather than importing, and cleaning up the CAD geometry before insertion will help keep the problems to a minimum.

You will find that you won't use every family or every group you create in your model. Revit has a tool that will allow you to get rid of those unused elements to help keep your file sizes down to a reasonable level. This tool, Purge Unused, can be found on the Manage tab on the Setting panel. If your file is very large, it can take several minutes to run, but eventually you'll be presented with a list (Figure B.5) of all the unused elements within your file.

Figure B.5. Use the Purge Unused dialog box to reduce file size.

Using this tool is typically not recommended at the beginning of a project while you are still trying many design solutions and file sizes tend to be fairly small.

As you refine your design, it's critical to model correctly right from the beginning, not taking shortcuts, so you don't have to fix things later. If you can begin by thinking about how your project will be assembled, it will save you a lot of time later in the process. It's good practice to plan ahead, but remember that Revit will allow you to make major changes at any stage in the process and still maintain coordination. If you are still in early phase of design and do not know the exact wall type, use generic walls to capture your design intent; changing them later will be simple.

When employing worksharing on a project, there are additional tools and tips you'll want to follow. Check out Chapter 6 for more details.

In a workshared environment, your local copy can begin to perform poorly or grow in file size while the central file remains small and nimble. If this is the case, it might be time to throw out the old local copy for a new one. As a general practice, if you're accessing a project on a daily basis, it's a good idea to make a new local copy once a week.

For larger projects or campus-style projects, you can break up your model into smaller submodels that are linked together. You can also do this on a single, large building. Dividing a model up helps to limit the amount of information you are loading into a project at one time.

If you decide to divide your project, make your cuts along lines that make sense from a holistic-building standpoint. Don't think of the cuts as you would in CAD, but think about how the actual assemblies will interact in the building. As an example, don't cut between floors 2 and 3 on a multistory building unless you have a significant change in building form or program. Here's a list of some good places to split a model:

Each time you create something that Revit considers a problem, a warning is issued. Warnings will accumulate if left unresolved. Think of all these errors as unresolved math calculations. The more there are, the more your computer will have to struggle to resolve them, and eventually you will have performance issues or file instability. To review the warnings, click the Warning button on the Manage tab. You'll get a dialog box like Figure B.6, which will allow you to search for and resolve the problem objects.

Figure B.6. Resolving errors

Sometimes when file corruption occurs it's due to a file that has grown beyond capacity of the machines using it. Reduce your file size using the tips above to make the model more manageable and resolve some of the errors.

Another way to deal with file corruption is to perform an audit on your file. You can find this tool in the lower-left corner of the File Open dialog box (Figure B.7). Auditing a file will review the data structures and try to correct any problems that have occurred. When it is completed, it will ideally be a fully functioning file again.

You can audit either a local file or the central file itself. Whenever you audit a file, you'll want to make a new central copy and have all of your project team create new local copies. The last thing you'll want to do is have someone with file corruption in a local copy synchronize those problems back to your newly fixed central file.

Figure B.7. Auditing a file

Revit is like a big calculator and it's very good at doing math correctly. Don't want to spend the time trying to figure out what your room size is after you subtract a 3⅝" and ⅝" piece of gypsum board from an 11"–2" room? Don't. If you need to modify a dimension, simply add an equal sign and a formula (Figure B.8) and Revit will calculate the value for you.

Figure B.8. Performing calculations in Revit

You want to add a gypsum soffit to the bottom of a stair or you want a sloped ceiling? Well, you can't do that with the ceiling tool. But you can with a ramp. Make a gypsum board ramp and align it to the bottom of your stair or angle it to create your sloped ceiling plane.

You want to create a shaft that will penetrate all the floors of your building and put an elevator in it that will show in all your plans. You could do this with an elevator family and cut a series of holes in the floors by editing floor profiles, but sometimes those holes stop aligning on their own recognizance. Fortunately, you can do both things at once using the Shaft tool found on the Opening panel of the Home tab. Here, you can not only cut a vertical hole through multiple floors as a single object, but you can also insert 2D linework to represent your elevator in plan (Figure B.9). Every time the shaft is cut, you're certain to see the elevator linework.

Figure B.9. Adding elevators to a shaft

Creating perspective views of isolated design elements can be quick and easy in plan or section, but let's say you want to see that same element in 3D to be able to work out the details.

— Submitted by Mark

Revit now allows you to edit your keyboard shortcuts without the hassle of rooting through your hard drive looking for a TXT file. To edit your shortcuts, click the Application button and select Options. Choose the User Interface tab and then the Customize button. The Keyboard Shortcuts dialog box (Figure B.10) will allow you to edit those shortcuts. Consider making common shortcuts the same letter. So, instead of pressing VG to get to your Visibility/Graphic Overrides dialog box, make the shortcut VV for quicker access.

Figure B.10. Editing your keyboard shortcuts

— Submitted by John S. from St. Paul, Minnesota

You need to load a family into Revit, you have the Explorer window open, and you know where the family is, but you don't want to go through the laborious effort of navigating across your office's server environment to get there. No problem. You can drag and drop Revit families from Explorer directly into the project file.

— Submitted by Tony D. from Kansas City, Missouri

You made the perfect 3D view in your last project, and you can't figure out how to get it into your current project. Fortunately, there's a way to copy views from one project to another. Open both files in the same instance of Revit.

Want to change everything that's cut in a view without having to select every family and change its properties? A quick cut poche is, well, quick:

Figure B.11. Using Override Graphics for a quick poche

— Submitted by Tobias H. from Boston, Massachusetts

Did you know that you can reorganize the tabs on the ribbon and place them in any order you'd like? Hold down the Ctrl key and select a tab (like Home). You can drag it left or right to change the order they appear in.

— Submitted by Tobias H. from Boston, Massachusetts

Open the Revit Help menu by clicking the question mark icon in the upper-right corner of the application. This tool will give you a basic synopsis of all the tools, buttons, and commands available in the application.

If you have purchased Revit on subscription, Revit Subscription Support offers web-based support. Their responses are speedy, their advice top-notch, and chances are they've seen your problem before. Subscription Support can be accessed online at subscription.autodesk.com.

Autodesk User Group International (AUGI) is a source for tips and tricks as well as excellent user forums. The forums are free to participate in, and it's a great place where you can ask questions, find answers, or discuss project workflows. AUGI is located online at www.augi.com. Once you're there, look for Revit Architecture.

Looking for content or families? Revit City offers another free online resource and has a growing database of families posted by users. See www.revitcity.com.

Here's a great reason to tell your IT department you need access to YouTube. Autodesk has its own channel that has some great content, it's free, and it has hundreds of short videos showing you how to perform specific tasks in Revit. See www.youtube.com/user/autodesk.

AECbytes is a website dedicated to following the trends in the AEC industry, with a strong focus on BIM, technology, and the direction of the industry, put together by Lachmi Khemlani. See www.aecbytes.com.

Revit Professionals is an online resource put together by Luke Johnson that is peppered with great tips and workflows with everything from tips on creating graphics to dealing with crashes. See www.whatrevitwants.blogspot.com.