The BIM side of AutoCAD is alive and kicking, thanks to a head start that allowed Autodesk to learn from some early mistakes. AutoCAD Architecture and MEP 2009 have both been around for a while, so the tools are pretty mature. In this environment (which is a BIM environment due to the fact that data is included with the object model that includes 3D components- building information modeling) There are a few areas I've found that are better but still need improvement:
- Electrical Panel schedules and circuiting are greatly improved, with side by side schedules now, and a more user-friendly Circuit Manager. Electrical load data is now stored in an external project database, instead of residing within a drawing file.
- Interference checking now includes both hard and soft interferences, which aid with clearances around objects such as panels, etc.
- The solution tips by themselves are a huge improvement - instead of just getting the "red circle of death" with no explanation of why things aren't working, you now get the "yellow triangle of hope" (I didn't make this up, this is what the folks at Autodesk told us -honest) - which provides solution tips for resolving the problem.
- Annotation scale tied to display configurations are a help, but if the user is following the intended process, this only helps when the user makes a mistake and has to change scale to fit a different size view, to have it fit on a sheet of paper. It's still a throwback to the world of having every view drawing in model space all stacked up on top of each other, and used in conjunction with a lot of layout tabs in one drawing. Nice and easy, but not as efficient as the view system of Project Navigator.
The overall design workflow is still around - place the equipment, add the connecting geometry and annotate the objects all still work the same way. But users are skipping over important parts of the application and missing the point.
Electrical is a great example - I've heard Building Systems users say they can't use the electrical components in ACAD MEP because the panel schedule doesn't look like what I've used. That's a load (no pun intended) - the symbols in the program show the same symbol that has been used for designing buildings for years. Where the process needs to change is that instead of storing my circuit/load data in some outside database such as excel, it should be embedded in the properties of the object and the style. Even if you're not using the panel schedule, you can still track loads when connecting the devices together in a circuit - and the program will tell you when you overload the circuit. The tag used to label the homerun will get its information from the device - so if you move items to another circuit, the tag will update.
It's this kind of process change the designers need to get used to. Instead of separating all of this data into different locations, the storage location becomes the object itself - utilizing the property set definitions. And the owners of the buildings are starting to realize that BIM products allow them to get this information in their CAD file - and are starting to require it as part of the deliverable.
Step 1 - Adding the Equipment
So how does it work? The designer started by selecting and placing primary pieces of equipment, such as air handlers, VAV boxes, power panels, lights, receptacles, pumps, etc. in the first segment. This is where AutoCAD deviates from Revit - Revit includes the step of assigning the components to systems, which creates a "target-source" relationship (i.e., the VAV box is a source to an air terminal, which is the target). AutoCAD doesn't track that relationship, although items such as air flow to an air terminal are assigned when placed.
The analysis tools used to determine the equipment sizes are also different at this point between AutoCAD MEP and Revit MEP. With both applications, spaces and zones are utilized to determine items such as volume, square footage, etc. Other items such adjacencies to other spaces has to be manually inserted, but both applications will recognize items such as openings for windows and doors. Revit will recognize more properties of these openings automatically, whereas in AutoCAD, you have to utilize the Space/Zone manager to identify the type of opening, location within the building, etc. We'll talk more about this in Revit section...
Both applications export to gbXML files, which are used by applications such as Trane Trace 700, Green Building Studio, and others to provide a more detailed analysis of items such as heating and cooling loads. Revit includes a portion of the IES Virtual Environment that quickly performs an Apache-based heating and cooling load analysis based on a calender year, with location, service type, building type and other design criteria that's embedded in the model. Some of this data can also been included with the AutoCAD MEP analytical model, but it has to be added through custom property sets.
Once the primary source equipment is placed, and general locations for targets are included, the designer should bet buy-in from all parties to complete the phase. Often times, we'll see designers already placing duct and piping in this phase, trying to deal with coordination issues, but this isn't the correct phase to be completing this task, as it creates additional work later to revise the layouts. Be patient and get the equipment as settled as possible - which means that the architect and structural engineer need to have their preliminary layouts nailed down as well.
And when I tell the designers that this is the way it needs to be, I usually get a lot of laughs - because somebody is always changing their mind, whether it's the client or the designer. IMHO, that's a cop-out - back in the days of the drafting table, you had to know most of this information early on anyway, so I personally don't buy the excuse. You CAN get buy in if you work as a TEAM - but you have to be willing to make concessions and share the same process in order for this to succeed.
Step 2 - Adding the Connecting Geometry
Back to the process - after the equipment layout is completed, that's when you start to layout the duct, pipe, etc. to connect the pieces. AutoCAD MEP includes a single-line duct tool that skips the sizes, but can be used to draw all of the double line duct later as a part of the sizing process. While Revit has a similar process, the drafting aspects begin to out-perform Revit at this point, as the AutoCAD side is much easier to work with when it comes to allowing the user flexibilty in layout. The system definitions in AutoCAD MEP are light years ahead of the limited system functionality of Revit, allowing the user to include pre-defined sizing parameters for the duct, as opposed to the one-supply-type fits all mentality of Revit.
Where the process started to break down is in really big projects - in AutoCAD MEP, we use the Project Navigator to manage all of the different levels and divisions. Since these are separate files, there are some breaks in the relationships between components that exist across these areas. The electrical load data is handled better with the inclusion of the EPD file (electrical project database), but the pipe side of life can't make that connection across multi-files (in fact you still can't size pipe in AutoCAD MEP). Other than that, the piping tools are vastly superior to what's in Revit MEP right now - we'll talk about that more on the Revit side....
Step 3 - Annotate!
It's always fun to see how users today are still trying to use old-style CAD methods to label their drawings - from placing text, dimensions and tags in paper space over a viewport just to get consistent text sizes to having multiple scale-based layers for annotation objects, which are usually manually turned on and off in a drawing. In the BIM world, this data lives with the object, so the program includes tools that extract this data to populate the tag - so instead if editing text, you're editing a property set definition of an object. This can be unique to an object or globally controlled by a style -but the process is the same. Sure, I can double click on a piece of text and change a light fixture type from an A to B - but that skips over the myriad of information that the light actually stores. By keeping the data with the object, and letting it update the annotations globally, is a vastly more productive process. In 2009, the ability of a tag MvBlock to include an attribute that can be grip-edited like an MText object is a great asset.
So, overall, the AutoCAD MEP side handles the replacement of manual drafting tasks with object oriented CAD extremely well. Its ability to handle large projects of manufacturing and industrial projects such as water and waste water treatment makes it an ideal choice for these types of jobs. If the user is very comfortable in AutoCAD, and is open to improving that line of process, it's still a solid and mature tool.
There are few areas that need improvement (display configurations still befuddle users, and the catalog/palette combination still is quirky but improved), but I can still use it on nearly every kin of design project. Its ability to work seamlessly with AutoCAD Architecture projects as well as plain AutoCAD backgrounds is a bonus. The IFC utility for this release that converts Revit Architecture projects into Project Navigator projects is really nice, and just needs some refinement.
So Why Isn't This Working?
The part the gets me is that the message isn't getting through to the project managers and design principals. One of my clients that's an owner that requires their consultants to provide them with AutoCAD Architecture and MEP models and projects (and also helps them offset training costs by providing the templates and CAD models back to them as part of the deal, rather than a bunch of garbage 2D drawings) complained to me the other day that they wanted to charge double for doing the project as a model. Their excuse? Their PM has their users doing the design work in 2D and then redrawing the model over top of the 2d linework as sketches - so they're literally doing the work twice. A simple lack of understanding about how to use programs such as AutoCAD MEP is what's causing them to fail.
As a consultant to the industry, it's been interesting to watch these trends develop. Older firms with the corresponding older principals. have been much less willing to accept a change in their process. Why should they? They've always made money in the past (well ,at least most of them did), but it's not always about how much money you make. The quality of design has become such a high priority. In this day and age where items such as LEED and sustainability, energy efficiency are as important as aesthetics and creativity, that the mentality of "letting the contractor figure it out" has become counter-intuitive. The tools have a much great potential of helping us avoid items such as interferences, project changes, and errors and omissions. No matter what world you're walking in, the reality is that the process that these tools utilize is changing how we do business - and the only thing to do to survive is adapt.
So, is AutoCAD MEP fulfilling the promise? In my humble opinion, yes - but it still needs to bake a little longer to fulfill the AutoCAD users that want to stay in that world.
Next - How Revit MEP Changes the Game in the Present....
thanks - David B.