First things first - let’s clearly define building information modeling or BIM, as it’s more commonly known.
Building information modeling is the process of generating and managing building data during its life cycle. Typically it uses three-dimensional, real-time, dynamic building modeling software to increase productivity in building design and construction. This information normally is produced in a database format, which allows the information to be utilized much more efficiently in the form of parameters.
The length, width, height, weight, color, material type, and other information can be controlled by these parameters, allowing the model to adjust three-dimensionally and in real time. This process allows the model to become parametric. These models allow the user to create more robust information than traditional two-dimensional CAD drawings, such as live building sections and elevations. This ability also allows for real time scheduling, sizing and tagging.
There are several software developers that provide products for BIM solutions for plumbing. Bentley Mechanical, Autodesk Revit MEP, VectorWorks and Graphisoft ArchiCAD with its MEP module are some of the more popular products used for plumbing design. Also be sure to visit the Web sites listed as references at the bottom of this article.
Now let me discuss some of the uses and benefits of using BIM for plumbing design.
When a plumbing designer first uses BIM for designing plumbing, he/she will normally become frustrated. It’s hard to beat the speed of drafting two-dimensional lines and circles. But as the plumbing designer gains more experience with BIM in their design, he/she becomes a better designer. Case in point: the challenge of routing under slab piping. With BIM, the designer will notice building footings placed by structural engineers to help maintain the structural integrity of the building. Further, as the underground is routed, the plumbing designer can coordinate the exact footing locations that may have to be stepped down to assure that the gravity waste line can be routed out of the building without issue. This will save money on the structural design.
Also, medical gas systems can be designed in different colors and reviewed in 3D to help prevent cross contamination. Real time sections can be cut through mechanical rooms or trouble spots to help resolve questions before they are raised in the field. Because the models are three-dimensional, isometrics are always available. (See Figure 1). While the layout may take longer to generate, the documentation portion is extremely efficient. As information is being added to the model in one location, all the views associated with that location are updated in real time.
LEED Plumbing DesignAs energy consumption increases, finding new and creative ways to conserve our resources for future generations also must change. The U.S. Green Building Counsel (USGBC) has created LEED (Leadership in Energy and Environmental Design) as a tool for green building projects. To receive points for reduction of potable water usage under LEED NC [new construction], a baseline must be established of plumbing fixtures as per the Energy Act of 1992.
Building information modeling can provide specifiers with two additional parameters of information about plumbing fixtures. One parameter will contain the required gpm flow of the standard fixture, the other parameter will contain the reduced gpm flow. As the plumbing fixtures populate the model, a schedule can be created to keep track of the totals for comparison.
Another benefit of using BIM in LEED design is ease of identifying systems. When designing a waste system for a LEED project, for example, a credit can be obtained by reusing gray water onsite rather than passing the burden on to the municipal wastewater treatment plants. The plumbing designer can use the BIM software to create different color systems to clearly identify gray water routing to help prevent cross contamination with other waste systems and to help calculate total gpm of the system as it is being designed.
This same technique could be applied to rainwater collection systems. For more information about LEED design requirements, visit the USGBC Web site, www.usgbc.org.
Code ComplianceSome engineering firms produce plumbing design work for multiple locations around the U.S. One of the biggest challenges is verifying code compliance with local authorities having jurisdiction. Many jurisdictions require that the fixture unit counts be shown in a schedule on the plans. When this schedule is produced with traditional CAD drawings, there is a chance of the schedule being overlooked if the information had been revised due to architectural updates or corrections. However, when a plumbing designer uses BIM for their plumbing design tool, the totals for fixture units can be adjusted automatically in the schedule as these new fixtures are added.
But what if the local jurisdiction uses the Uniform Plumbing Code and the schedule is based on the International Plumbing Code? This issue can be corrected by adding two parameters, one based on UPC plumbing fixture unit counts and another based on IPC counts. By filtering the schedule, the proper fixture unit can be displayed. This schedule can also be used to reference the number of plumbing fixtures in the model verses the plumbing fixtures required by code.
Another example of using BIM for code reference is in the design of natural gas systems. By creating a gas equipment schedule, the totals can be easily displayed for sizing purposes.
The International Code Council (ICC) is in the process of developing standards for the review of building information models. This initiative is called SMARTcodes™, which works on the concept known as “interoperability.” To be interoperable means to share and use information across various interests and disciplines. In this case, the use of information technology will help building departments deliver more efficient and effective public services and enhance public safety. It will also help designers, specifiers, contractors and others more effectively address code-related issues.
The goal of SMARTcodes is to automate code compliance checking for the I-Codes and federal, state and locally adopted versions of those codes, leading to enhanced communication, knowledge and collaboration; more-complete code-complying designs;more-timely design acceptance and approval; improved building safety and performance; and reduced construction costs. ICC is developing SMARTcodes in coordination with the buildingSMART alliance, a Council of the National Institute of Building Sciences (www.nibs.org). For more information, refer to www.iccsafe.org/SMARTcodes/index.html.
Interference CheckingOne of the most powerful points of using a BIM solution for plumbing is interference checking. With the economy currently experiencing slower growth, every penny that can be saved could be crucial to the owner’s ability to get their business going. This concern drives the architectural firms to design very streamline projects. This means smaller ceiling spaces and minimized wall chases.
With increased building constraints, coordination must be observed very closely. Ductwork, structural steel, lighting and sprinkler piping must also run in these confined spaces. Using building information modeling to coordinate these obstructions can reduce conflicts during design and help prevent costly change orders during construction.
There are several ways of accomplishing this task. The first is visual review. Being able to see every discipline in a three-dimensional environment can help tremendously in determining design options. (See Figure 2).
Another option is running clash detection within the BIM software. As discussed earlier, most BIM models are parametric. Every item in these models has the ability to be programmed with substance and information. Most BIM solutions have the capability of performing clash detection to see if any items are crossing each other, such as sprinkler piping and ductwork. Once this clash detection has been run, it will show the results of the issues that the program discovered. (See Figure 3).
A product called Navisworks has the unique ability of being able to coordinate with most BIM solutions (including CAD-based plans) in one model. A few general contractors are beginning to use this product to help with cost overruns by detecting problems before the construction begins.
ConclusionPlumbing engineers and designers have been managing building information through the use of specifications and blueprints for years. I would describe this as building information management. Building information modeling is an evolution of this concept. As with any new concept, it will be several years before building information modeling becomes the industry standard for design.
The early adoption of BIM can be plagued with problems, mainly as a result of underdeveloped software. Learning new technologies often requires a positive attitude, dedication and resilience. But, as with CAD, plumbing designers can develop methods to effectively use BIM to their advantage and produce a design that will give their client the best product for the money. I have tried to demonstrate just a few of the benefits that can be reaped while using these new technologies for plumbing design. To learn more about BIM, please visit the Web site of the National BIM Standard: www.buildingsmartalliance.org/nbims.
ReferencesAutodesk Revit MEP 2009 http://usa.autodesk.com
Bentley Mechanical www.bentley.com
ArchiCAD MEP Module www.graphisoft.com/products/archicad/solutions/mep_modeler.html
ICC Smartcodes www.iccsafe.org/SMARTcodes/index.html
U.S. Green Building Council www.usgbc.org
National BIM Standard www.buildingsmartalliance.org/nbims