×

AEC

1-2-3 REVIT: BIM for MEP Engineering

11 Apr, 2006 By: AIA ,Rick Rundell

---

Revit Systems brings the power of building information modeling to MEP engineering.

Autodesk recently announced the availability of Autodesk Revit Systems--purpose-built BIM (building information modeling) software for MEP (mechanical, electrical and plumbing) engineering (figure 1). This release expands the scope of the Revit family of products, delivering a complete BIM platform for collaborative multidisciplinary building design.

This month, I begin a three-part series of articles about Revit Systems: exploring how BIM improves the MEP design processes and examining how those processes are enhanced when combined with Revit-based architectural and structural workflows. In the coming months, I'll delve deeper into Revit Systems and examine how BIM affects mechanical design (next month) and electrical design (the following month).

MEP Industry Trends
Today's demanding business environment is driving toward greater efficiency and integration in building industry supply chains. Owners are demanding better built buildings for less money in less time. Architects, engineers and contractors are under pressure to streamline their building design and delivery process--and searching for ways to improve productivity, lower costs and deliver better quality products.

The success of BIM for building design--as evidenced by the rapid adoption of BIM solutions such as Autodesk Revit Building--is redefining clients' expectations of their MEP consultants. Similar to BIM for building and structural design, BIM for MEP is a design and documentation methodology characterized by the creation and use of coordinated, internally consistent computable information about a building's MEP system in design and construction.

MEP Design Using BIM
Revit Systems uses a holistic approach for system modeling--MEP design is done in the context of the whole building. For example, the electrical and mechanical systems know about each other, so an electrical engineer can track the power requirements of the mechanical equipment included in the design and the software can automatically configure electrical load requirements to dynamically change in mechanical equipment specifications.

This holistic approach unites not only the MEP disciplines but the whole design process with an integrated digital environment for design, documentation and analysis. When used in conjunction with other team members and Revit-based design applications, this holistic approach expands to include the rest of the building.

During design, Revit Systems features automatic sizing and systems layout tools and provides engineers with immediate feedback about their designs (figure 2). For example, during the layout of a mechanical system, Revit Systems displays the critical flow path for branches, main trunks or the entire system. This feedback then allows an engineer to quickly identify areas of the system with the highest pressure loss and then modify the design for maximum performance and efficiency.

Automatic interference checking during the design process is another valuable feature of BIM (figure 3). Typically, a building's architectural and structural systems are defined well in advance of its MEP systems with only standard space allowances reserved for the latter. These reservations set the stage for inevitable conflicts between the area needed for those MEP systems and the overall cost of the building. In large, complex building designs such as hotels, high-rise apartment buildings or office complexes, squeezing the required MEP systems above the ceiling becomes particularly challenging. Revit Systems offers a 3D modeling environment for mechanical and electrical layout. This modeling environment helps the MEP designer overcome the challenges of fitting the required components into tight spaces and then provides interference checking to detect collisions during the design process, which reduces the risk of construction cost overruns.

Revit Systems also supports key aspects of sustainable design and certification by facilitating complex processes and analyses. For example, Revit supports export to gbXML for use in third-party energy and heat load analysis applications, including Green Building Studio and Trane's TRACE 700. MEP engineers can use the information created in their Revit Systems BIM to test the performance of their design and eliminate the time-consuming task of transferring data manually.

Parametric Change Management
The majority of MEP engineering solutions today are based on CAD technology with a focus on the production of construction documentation rather than the engineering design. In previous articles, we've explored how additional effort and tools are required to manage and coordinate the building design data of these CAD systems.

In contrast, Revit Systems is a purpose-built BIM solution for MEP design--built on a parametric change engine that provides immediate, comprehensive change propagation through the natural operation of the software. The entire building model, including mechanical, electrical and plumbing systems, can be in an integrated database in which everything is interconnected. This database provides reliable, coordinated and consistent design information and documentation that characterizes BIM. The parametric nature of Revit Systems lets users focus on MEP design and virtually eliminates coordination errors.

Inside Revit-based Workflow
Because Revit Systems is built on the Revit platform, coordination between MEP team members using Revit Systems, architects using Revit Building and structural engineers using Revit Structure is streamlined.

The architectural spaces created using Revit Building can be used by Revit Systems to support load calculations, track airflow in rooms and coordinate panel schedules. The architectural and structural elements created by Revit Building and Revit Structure, respectively, can be used to uncover potential conflicts with MEP system components early in the design process.

Well-established processes for Worksharing among Revit users equally apply to MEP engineers using Revit Systems. Revit Worksharing distributes the power of the parametric modeling environment across a project team to provide a complete range of collaboration modes to suit the workflow and requirements of the parties involved, including the following alternatives:

• On-the-fly, simultaneous access to a shared model between architects, structural engineers and MEP engineers.
• The formal division of the project into discrete shared worksets (such as "floor_1_architectural," "floor_1_structural," "floor_1_mechanical," "floor_1_plumbing" and so on) that are reserved for editing by a single user at a time.
• A complete separation of project elements or systems into individually managed but linked building databases to form an integrated building information model.

File linking works similarly to AutoCAD's external reference (xref) capability with the added capability to monitor and update specific key elements that are shared in the design process (figures 4 and 5). Worksharing offers the additional ability to propagate and coordinate changes between designers, documentation and disciplines. A user works independently in a workset, periodically posting changes back into the master project file and refreshing the workset with changes from other users. Worksets can be displayed as needed to avoid the memory-intensive display of parts of the building model that aren't necessary for a specific design activity (figure 6). For example, an electrical engineer may want to view the architectural workset constantly but toggle the visibility of the structural workset on or off to suit his or her design needs. Standard model-viewing mechanisms are supported for worksets to enable MEP engineers to create drawings that include any elements from shared models.

Purpose-built BIM
A purpose-built BIM solution such as Autodesk Revit Systems improves a firm's productivity, accuracy and coordination in its MEP design and documentation process. Firms can finally transition from a workflow based on 2D drafting to the holistic approach of integrating systems in a 3D digital environment and facilitating digital information sharing for engineering analysis and digitally-driven design for buildings.

Consider these comments by Bob Gracilieri, president and CEO of SEi Companies. With offices in Boston, Houston and Washington, DC, SEi is a mechanical, electrical, plumbing and fire protection firm. "BIM brings a new dimension to the way MEP firms can do business," said Gracilieri. "It allows us to get out of the commodity mode and offer a value proposition service to our clients. It will change the whole culture and image of our industry."