Revit MEP: Lucky 13

I am sure there will be plenty of references to the unlucky nature of the number 13 (especially for Autodesk), but with the combined improvements in the base product and the Autodesk® Revit® MEP features, my feeling is the 2013 version of Revit MEP may turn out to be quite lucky indeed. This version has some little tweaks that have been long awaited, some nice upgrades that make life much easier, and some major updates that will change the way we work. Chances are you want to hear the big news first, but keep reading; even the small changes will be meaningful to the way you work every day.

Major Updates

Materials Now Have Thermal Properties 

The ability to specify thermal properties to materials is my number one feature for Revit MEP 2013, even though it is technically a platform addition. This addition sets the stage to leap forward and use existing architectural data for HVAC load calculations. Until now MEP engineers have had to input their own data. Now the material used by the architect can be assigned thermal properties that can preloaded into the HVAC dataset and updates as the model changes. I am pretty sure that was the whole idea of BIM in a nutshell.

Revit will treat assemblies different than component walls. Component walls set R and U values, Solar Heat Gain coefficient and Visible light transmittance from a list of analytic constructions. Assemblies allow the user to set each element type an Absorptance and Roughness. R and U Values along with Thermal Mass are calculated based off the material of each layer in the assembly and its thickness.

Figure 1

This data can be used for analysis inside Revit MEP or exported to GBxml. Just check the “Include Thermal Properties” box when exporting to GBxml to derive thermal data from the model.

Pipe Segments

The size lists found in the Mechanical settings under Pipe is now Pipe Segments. This allows pipes of the same system and differing materials to exist and connect.  The Segments and Sizes portion of the Mechanical Setting dialog allows the user to pick the segment type, change the roughness, add a description, and specify a default connection. Sizes can be added from here specifying inside and outside diameters and if the size is included in size lists or used in sizing routines. New segment types can be created in this dialog by selecting the “Create New Pipe Segment” tool. New types must be specified by material, schedule/type, or both. The materials browser can be launched from the new Segment dialog, meaning pipes can be made out of anything.

System Inspector on Duct and Pipe Created with Taps 

Duct and pipe created with taps now calculate separately for each segment. This can be viewed with the system inspector on systems that are set up properly. The system inspector will show the flow, static pressure, and pressure loss in a duct segment when selected.

Color Fills on Duct and Pipe Created with Taps

Color fills also now work on duct and pipe where taps have been used by segment. View by using the Duct legend or Pipe legend tools on the Analyze tab of the ribbon. This is a great tool to quickly review velocities, flows, and to look for trouble spots.

Duct and Pipe Routing Preferences

A “Routing Preference” tool has been added in the type parameters for duct and pipe under the fittings category. In this dialog the preferred fittings can be listed. The duct routing preferences show the preferred fittings and junction type. The Pipe routing preferences also shows minimum and maximum sizes, giving the ability to specify fitting types by size. Instead of a size the word “None” can be used to ensure the fitting will never be used during a layout, or the word “All” can be used to require that fitting is used every layout. Otherwise, the layout will respect the size constraints in the type.

Figure 2

An added bonus to using “None” is that when switching fitting types, there is now a “Constrain to routing preferences” checkbox in the type selector that will limit the fittings listed in the type selector to only those specified in routing preferences. In the case below, there is only one fitting to look at. That makes picking it real easy.

Figure 3

Reapply Type

A Reapply Type tool has been added to allow the user to make changes to the routing preferences and then apply those changes to duct or pipe that has already been modeled. This can be a quicker way to update a layout with different fittings.

Figure 4

Pressure Loss Reports

Figure 5

Pressure loss reports can be generated as CSV or HTML files using the tools on the Analyze tab for duct or pipe. This will take the user to a system selection dialog. This step can be skipped by right clicking on a system in the System Browser and selecting the appropriate pressure loss report tool there. The pressure loss report lets the user specify available fields much like building a schedule. Pressure loss reports can only be generated if the systems calculation method is set to “All.” See Figure 6 for a typical pressure loss report.

Figure 6

Nice Upgrades

Centerlines on Round Elements

Revit MEP can now generate centerlines for round elements such as duct, pipe, and conduit. Revit will show centerlines in plan and elevations views when hidden line is on. Centerlines will not be visible in 3D views. When perpendicular to the plane of view, the centerline will show up as a cross hair. Centerlines in objects passing under other elements will not show up. Centerlines in fittings only show up if a profile is found. A centerline can be added to a fitting family by adding the centerline category and changing the appropriate model line to a centerline.

Figure 7

Specify Rooms or Spaces

Now when exporting to GBxml the user can has the option to specify rooms or spaces. Depending on the information required, one may work better than the other.

ASHRAE Database Update 

The ASHRAE duct fitting data base has been updated to version (5.00.00). 78 out of 235 tables were updated and the coverage of pressure loss data in fittings has increased.

Figure 8

Air terminals now have a toggle to turn on a room calculation point. This will allow the air terminal to connect to a room space when they do not occupy the same space. This fixes the problem of room objects that are lower than the diffusers not communicating the assigned CFM. The user can turn on the calculation point and then move that point in a section view to connect it to the room.

Figure 9

Little Tweaks

Systems Tab 

The Home tab is now called Systems. Catchy, but not as good as three separate tabs that say Mechanical, Electrical, and Plumbing, or the dimension tool that doesn’t ask if we prefer wall centers or faces.

Figure 10

Plumbing Discipline  

If you can remember the very first version of Revit Systems and you are a plumber, you’ll recall that there was no plumbing back in the day. Well, Plumbers, rejoice because plumbing now has its own view discipline to go along with all the pipes, fittings, and fixtures we acquired over the years.

Figure 11

Site Tools

Well, I guess you never know when you might want to mass something up or throw down a toposurface. If that is the case, there is nothing stopping a MEP user now. The Massing & Site tab found in Revit Architecture is now in Revit MEP.

Figure 12

Category Filtering

This is another one of those platform changes that really feels like a gift to MEP users. Now when in Visibility Graphic Overrides there is a filter list that includes Architecture, Structure, Mechanical, Electrical, and Piping. This is an improvement (even though Piping should be Plumbing).

Figure 13

Underlay Orientation for RCPs

An incredibly annoying thing of the past was creating a new ceiling plan and having to go back and change the underlay orientation to reflected ceiling plan to see the ceiling grids. Now the underlay orientation of new ceiling plans is RCP by default. That is one less thing to do and something I don’t have to explain ever again, I hope.

Figure 14

Double Click Scroll to Zoom All

One of the things Revit got right very quickly was aligning the view controls in the mouse with good ol’ AutoCAD. With one notable exception, double click the scroll wheel to zoom all. If you are like me, you double click the scroll wheel constantly, waiting in vain for Revit to react. Now those days are over. A small change, but it makes me very happy.

Diameter Prefix

The Diameter symbol can now be specified as a prefix. This is another behavior that the entire MEP world has had to work around for six versions. Thank goodness it’s over.

Rise and Drop Symbology

There are rise and drop graphics for rectangular and oval-shaped duct. This helps a lot since duct tends to go up and down as well as side to side.

Figure 15

Loop Leader

I have actually begged for this. I asked Santa Claus, I offered $20 to a programmer, and I spent hours trying to crack the API to make my own loop leader.  Until now my efforts were for nothing. At long last we have the choice of a loop leader for arrow styles. By far, my favorite little tweak and very long awaited.

This release has plenty to offer. The program itself is evolving before our eyes into a much more complex engineering tool while improvements to its base ability to draft are still being added and modified.

As I said in the opening paragraph, it is well worth the upgrade. Not just for compatibility with architectural project files, but also to exploit the engineering capability it offers. No doubt the longer one waits touse Revit to its fullest, the farther one will fall behind those who throw caution to the wind and dive in. The water is fine and the time is right for Revit MEP 2013.

Todd Shackelford is the BIM Manager for Alvine and Associates, the president of the BIM Board of Omaha, and an instructor for the University of Nebraska. He authors three Blogs: CAD Shack , The Lazy Drafter and Revit Basics. Todd has been a featured speaker at Autodesk University, AUGI CAD Camps, CSI, IEEE and AIA events. Contact Todd at

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