Revit MEP

Revit MEP

Wednesday, July 30, 2008

Revit MEP System Run Selection

Revit MEP has a different method for resizing ducts and pipes. In AutoCAD MEP, you select a single duct (or pipe) and specify a new size and then the software asks whether you want to resize the run up to the next junction or to include a transition. This is potentially asked twice if the duct (or pipe) is connected to a run at both ends.

Revit MEP differs in that if you want to re-size a run of ducts or pipes, you explicitly select which ducts or pipes are to be modified. To simply this process, there is a procedure for a selecting a run of ducts or pipes.

First select the start of the run:

Then select the end of the run while holding down the Tab key:

You can now specify the new size in the Options Bar:

Revit Family interaction with Ceiling Grid

Place families in the centre of a ceiling grid tile.

To ensure that Revit families interact with ceiling grids and automatically find the center point of a tile, you need to consider how the family is defined. For example, imagine an air terminal that automatically locates each ceiling tile as it is moved around.
To do this, create or edit a family to add reference planes, which will give a strong reference when moving the family around.

Reference planes are used because the air terminal in this example is 24 x 24 and it needs to be placed in the center of a 24 x 24 ceiling tile.

The reference planes placement is marked with red in the figure below.

By making sure that the added reference planes are used as strong references, the air terminal will now automatically highlight the ceiling grid lines when a reference plane comes near to it, making it very easy to place the air terminal and lock it to the ceiling grid line.

Where the reference planes are added will depend on the individual family and the required functionality.

Friday, July 25, 2008

Revit Extensions for Revit MEP 2009

Download Revit® Extensions are a series of easy-to-use applications that extend the capabilities of Revit® MEP 2009 software in key areas, including modeling, coordination, and documentation. Specifically, the extensions provided in this executable file are: Freeze Drawings, Compare Models, Text Generator, and Elements Positioning. The file installs the Revit Extensions for Revit MEP 2009. It also includes the Extensions Engine, a platform that hosts each Extension within Revit MEP 2009.


  • "Revit Extensions for Revit MEP 2009" may be installed by users with the Administrator" or "Power User" rights (in the Windows VISTA operating system, only by users with the "Administrator" rights).
  • "Revit Extensions for Revit MEP 2009" installed by the user with the "Administrator" rights can be launched on a given computer also by users with the "User" and "Power User" rights.
  • Before launching "Revit Extensions for Revit MEP 2009" by the user with the "User" or "Power User" rights Revit should be launched one time by the user with the "Administrator" rights (in the Vista operating system, with an additional parameter "Run as an Administrator").


  • To launch "Revit Extensions for Revit MEP 2009" first run "Revit MEP 2009".
  • A new toolbar is displayed containing 3 new icons:
  • Click to launch the "Revit Extensions Manager", run a particular extension or read help for further information.
Compare models Extension
Using the Compare models extension, you can compare 2 Revit® models. The extension presents differences between successive versions of a structure project.

When the extension starts, it recognizes the number of opened projects created in Revit®. If more than 2 structure projects are opened, a dialog displays where you can select 2 projects to be compared.

Comparing structure models that were created as a result of copying elements (for example, through the Clipboard) may not lead to good quality results. Original element identifiers (ID) may be changed in the extension, which makes element identification and correct comparison of models impossible.

After you have selected 2 Revit® models, the main dialog of the extension, used for comparing models, displays. The dialog consists of 3 tabs: General information, Elements, and Report.

Element Postioning Extension

The Extension is used to create position tags for selected elements in a Revit ® model. All element types available in Revit ®, except annotations and loads, are taken into account during positioning.

After elements and positioning parameters are selected, element tags / names (for all elements or for selected ones) are generated in the Extension. Position tags are placed in the element properties (in the Mark cell), in the current (start) view, or in views you select (the option specified in the Extension).

Basic functionalities of the Extension:
· create a set of elements and divide them into categories and types
· sort elements depending on their location in the project (horizontal or vertical)
· add a tag describing a user-defined position at the location specified in a selected view.

The Extension allows loading necessary information from Revit MEP:
· object category (column, beam)
· object family (regular I sections)
· object type (I 100)
· object geometry
· object location (level)
· material of which the object is made (after you select the option)
· bars reinforcing RC elements (after you select the option).

If positioning is performed for standard levels, two descriptions may display for some elements: description of the element positioned below (for example, a column positioned on the lower level) and a description of the element positioned on a given level (see the image shown).

A solution to this problem (in particular, when dimensions of elements on two levels are identical) is to make a cross-section at a selected height in Revit ®; for this cross-section, a position number should be displayed.

All data defined during the element positioning can be edited using the Modify option.

Freeze Drawings Extension
Using the Freeze Drawings extension, you can separate a drawing / view from an object model so that the state of the drawing / view stays unchanged (frozen). The extension is based on the DWG Import and DWG Export mechanisms in Revit®.
All frozen drawings / views are placed in newly created views. Selected views are imported to DWG files with user-defined parameters.

Freezing of drawings does not include 3D views or sheets

Text Generator Extension
Use the Text Generator Extension to generate text automatically in Revit®. You can type text directly in the relevant edit field or load text from an external file, and can also define the parameters.

Thursday, July 17, 2008

Coordinating MEP Space Tags with Architectural Room Tags

Matt Dillon's Blog, "Breaking Down The Walls" explains that when you link an architectural model into your MEP model, you can use the Space tool to place MEP Spaces wherever the architect has placed rooms, giving you full and independent control over the upper limit offset and other analytical properties.

The problem is, the Space Tag that is added to the Space has no obvious relationship to the original architectural room name or number in a linked project. The Space has it's own name and number! Rather than manually editing the Space properties to match the room name and number (and running the risk that either the room name or number could change in a subsequent reload of the architectural model), you can make a simple edit to the Space Tag family to keep the Space and Room in sync.

See how here =>

Thanks Matt

Friday, July 11, 2008

MEP Analysis Extension for AutoCAD MEP/Revit MEP

Autodesk announced that the company is making two extensions for AutoCAD MEP and Revit MEP available to mechanical, electrical, and plumbing (MEP) engineers to design more efficient building mechanical systems. The MEP Analysis Extension, available as a free 30 day technology preview from Autodesk Labs, is a set of 25 utilities that MEP engineers can use to better understand how a building system will perform before it's built, ultimately helping MEP engineers reduce energy costs and environmental impact while improving the performance of building systems. The HVAC Load Calculation Extension, available for Autodesk Subscription customers of AutoCAD MEP and Revit MEP, performs peak cooling and heating load analysis for commercial buildings so that engineers can properly size HVAC equipment. Both extensions can function as stand-alone applications, but also work in conjunction with both AutoCAD MEP and Revit MEP.

The MEP Analysis Extension calculates rule-of-thumb cooling and heating loads for commercial and residential buildings, calculates total R-Values for walls and roofs, determines psychrometric properties of air, and more. Running these types of calculations through the MEP Analysis Extension can help MEP engineers reduce error and waste, potentially saving energy costs, the company states. The MEP Analysis Extension also contains utilities for sizing duct work, piping, and HVAC systems, helping engineers and architects identify the most appropriate building equipment early in the design cycle.

The following utilities are included in the MEP Analysis Extension:

  • Metric to English units converter
  • single-state psychrometric calculations
  • mixed-air psychrometric calculations
  • duct sizing calculations
  • ASHRAE duct fitting pressure loss calculations
  • general pipe sizing
  • hot/chilled water pipe sizing
  • steam pipe sizing
  • low-pressure gas pipe sizing
  • high-pressure gas pipe sizing
  • refrigerant pipe sizing
  • fan cost analysis
  • fan curve analysis
  • pump curve analysis
  • rule-of-thumb commercial HVAC load calculations
  • simple residential/light commercial HVAC load calculations
  • swimming pool heating calculations
  • u-value calculations
  • gbXML parser
  • wire sizing utility
  • glass moisture condensation
  • life cycle cost analysis
  • a super calculator for complex equations
  • manage HVAC equipment lists
  • manage climatic weather data

The HVAC Load Calculation Extension is a comprehensive HVAC (heating, ventilation, and air-conditioning) load calculation software tool that determines building peak cooling and heating loads based upon current calculation techniques from ASHRAE. Using the results from the software, engineers can properly size cooling and heating equipment without oversizing such equipment, which often results in wasted energy. The Load Calculation Extension works as a stand-alone application, but also integrates easily with BIM modelers such as Revit MEP.

The first utility is a “Duct Sizing Calculations” utility that performs duct sizing based upon air-flow, velocity, duct material type, and additional inputs. The results contain duct size dimensions (for rectangular, round, or oval shaped ducts), pressure loss values, and other pertinent information. One convenient feature is the “slider-calc” functionality that allows instantaneous results as the user ever-so-slightly increases or decreases different values using a slider control:

The second utility is the “Duct Fitting Pressure Loss Analysis” utility that allows engineers to determine the pressure loss in an individual duct fitting (such as an elbow or wye). Using these results, the engineer can determine the total pressure loss for a duct system. Some of the inputs that are required by this utility include the air flow, duct inlet and outlet dimensions, and air temperature. The final calculated result includes the total pressure loss through the duct fitting.

An engineer can use a combination of the above utilities to design simple duct systems in a building, ensuring that duct runs and air handlers are properly sized so that energy is not wasted on powering oversized fans.

The MEP Analysis Extension is available as a free technology preview from Autodesk Labs. Visitors to Autodesk Labs are encouraged to experiment with inventive new tools and provide feedback to the Autodesk team. The HVAC Load Calculation Extension is available to customers of AutoCAD MEP 2009 and Revit MEP 2009 on Autodesk Subscription and is subject to Autodesk Subscription terms and conditions. The extension is currently available in English only, but will operate with all language versions of AutoCAD MEP 2009 and Revit MEP 2009 software.

The extension will run through October 31, 2008.

Available as a Technology Preview feature, the Extension is programmed to expire within 30 days of installation. They are offering this extension to get feedback to help them make better products and technology, and it plays an important role in determining the future of the Extension. Tell them what you think!