For many decades, the AEC community has relied on a paper-based workflow with designers working in “silos” that focused on a single project discipline or function and sequentially passing the outputs of their design decisions on to the next discipline. This isolated, sequential process created many barriers to effective collaboration and has often led to misunderstandings and mistakes requiring costly rework in the field.
In recent years, designers in the AEC community have embraced a new methodology using BIM software tools and building information models as the basis for a collaborative design process to meet the challenges of today’s increasingly complex and demanding project requirements. Using this BIM methodology, design teams can deliver projects on time, at a higher quality, and with greater efficiency.
While the local benefits of adopting a BIM-based design approach to improve the workflow and outputs of each design discipline—architectural, structural, and MEP—are typically far greater than the costs of deploying BIM and sufficient to justify making the change, the larger impacts of enabling seamless multidisciplinary collaboration by the entire design team are far greater.
While the transition from manual drawing to CAD-based approaches improved the efficiency of the process, the transition to a BIM-centric design approach fundamentally changes the process and the AEC workflow by revolutionizing the way project information is shared, coordinated, and reviewed. BIM is proving to be a breakthrough technology that affects project workflows, multidisciplinary team roles, delivery methods, and project deliverables.
Advantages of a BIM-Centric Design Approach
A fundamental advantage of using a BIM-based methodology for sharing project information and collaborating is that it enables design team members to participate and provide their inputs much earlier in the design process, rather than waiting in line for their turn after earlier design decision are locked. This early participation and input enables all design team members to assess the impacts of their design decisions and processes downstream.
When the entire team can coordinate their work and share design inputs, they can easily assess the impacts of design alternatives and hone in on the best options earlier, and in parallel. This collaborative approach enables designers to respect the requirements of the other design disciplines and avoid costly and time-consuming conflicts and design rework.
Multidisciplinary Design Teams
As the design and construction of successful buildings becomes increasingly complex, designers and experts from many disciplines must be brought together to share their expertise and collaborate on the design of the key building features. Typically, all of the disciplines and expertise required cannot be found in a single design firm. Rather, a project design team typically involves designers and experts from a number of different firms that all specialize in their own aspect of the project design.
A typical project team may bring together architects, civil engineers, structural engineers, mechanical engineers, planners, surveyors, and a host of technical specialists—each with their own perspectives and goals on what features will create the best design. These designers may also be joined by constructors and fabricators who will build the project, as well as the facilities personnel who will eventually operate the completed building. Coordinating the inputs from all these divergent viewpoints into a collaborative process can be a monumental task.
To achieve their design goals, design teams must produce and manage vast amounts of information about the project—for example, existing and as-built conditions, project goals, design options considered, results of design analyses performed, construction planning and fabrication strategies. A seemingly boundless range of details must be coordinated, reviewed, and agreed upon by the entire team. Each team member must develop the information needed and design the features required for their own portion of the design work, and this information must be shared with other members of the design team who are impacted by and depend upon these design decisions.
A BIM-centric design approach enables multidisciplinary design teams to create, share, and coordinate vast amounts of project information, maintaining the integrity of the design team’s information and decision-making as the project evolves. Traditional paper-based approaches are just too time-consuming, error-prone, and limited to effectively meet the needs of the today’s multidisciplinary design teams.
Developing a Model Coordination Plan
Before members of the design team dive into creating models for their individual pieces of the project, it is essential that key members of the team meet to create standards and document the procedures that will be used to share models. This step is often formalized in a Model Coordination Plan or a BIM protocol document that specifies:
- The overall strategy for dividing the design work into packages that will be completed by different members of the multidisciplinary design team.
- Who is responsible for the development and analysis of each work package at each stage of the design process.
- The acceptable level of detail for each work package at each stage.
- The information exchange mechanisms (network server, FTP site, or other file transfer means) and standards (file formats).
- Who has management or editing privileges for each work package.
BIM-Centric Design Workflow
The precise workflow used by each multidisciplinary design team will vary based on the specific needs, requirements, and relationships between the team members. The following steps outline one suggested approach:
Step 1: Create a Base Design Model
A common first step in the project design process is for the lead architect to generate a preliminary design in response to the owner’s requirements and other design objectives and constraints.
Autodesk® Revit® Architecture software can help architects to explore and assess to meet their design objectives—for example, maximizing usable space, responding to site features and constraints, maximizing building performance, and creating desired design and aesthetic effects—to name just a few possibilities. Whatever the design priorities, BIM helps architects to explore design alternatives and document their design intent.
Step 2: Utilize the Base Design Model
Once a preliminary design has been created, the BIM model can be shared with other members of a multidisciplinary design team to be used as a starting point for their design tasks.
The BIM model of the preliminary design encodes the design intent of the architect and enables other team members to participate and collaborate much earlier than traditional silo-based, sequential workflows. Each discipline can link the architect’s preliminary design model into their own model (which acts as a host for the linked model) and use the linked model as the basis for their own design work.
Autodesk® Revit® software products provide collaboration tools that help the multidisciplinary designers to selectively copy and monitor elements from the architectural model that will inform or affect their own design as well as elements that created interdependencies between the designs. This capability helps designers to quickly create coordinated models of the project to support their own workflow. To simplify the workflow and avoid degrading the performance of their host model, designers should only copy the elements needed to coordinate work with other team members.
Having created linked models, each member of the design team can then complete their individual design tasks in parallel, confident that their design work will remain coordinated with the work of other members of the team:
- Structural engineers can design and model the structural members and framework required to support the proposed design and recommend changes that will improve the structural performance. They can also use their structural models as the basis for structural analyses and detailed structural design. The results of their analysis and design can be linked and incorporated into the overall project model to ensure coordination with other members of the design team.
- Electrical and lighting engineers can design and model the power, lighting, and switching systems needed to support the requirements of the proposed design. They can use their electrical models to perform detailed analysis and design of the buildings electrical systems and recommend changes that would improve the building performance. As with other disciplines, the results of their electrical system analysis and design can be linked into the overall model and coordinated with other design team members.
- Plumbing engineers can design and model the water supply, sanitary, and fire protection systems needed to support the proposed design. Using the space layouts, fixtures specified, and wet walls initially proposed by the architect, the plumbing engineers can model the pipe routing and perform analysis on water flow and pressure to design the components of the plumbing system in detail. When their proposed design is linked into the overall model, their work will be coordinated with the work of others.
- Mechanical and HVAC engineers can also use the linked preliminary design to understand the building’s cooling and heating zones as well as the spaces available for mechanical equipment and chases and plenums to route ductwork. They can position their HVAC components in the context of the architectural, structural, and other building elements that may create interferences, thus maintaining the integrity of the integrated project design.
Step 3: Review and Coordinate Designs
As each discipline completes an iteration of their design work, their models can be linked to an integrated project model that incorporates the models produced by all disciplines. This essential step facilitates review, coordination, and interference checking between all of the design work that has been carried on in parallel.
Every discipline’s individual design decisions can have impacts on many other disciplines, especially where elements from many disciplines must be coordinated to share small spaces—for example, in a ceiling space where structural elements, mechanical ductwork, and piping systems all compete for limited space. This is where design review and coordination among all participating disciplines becomes vital.
In traditional paper-based workflows, coordinating drawings created by many disciplines could be a time-consuming and tedious task fraught with human errors, because conflict and issue identification relied on human interpretation of 2D drawings. In a BIM-centric design process, computers can automatically and reliably check vast number of potential conflicts almost instantaneously.
Revit products enable cross-linking of models created in Revit Architecture, Autodesk® Revit® Structure software, and Autodesk® Revit® MEP software. The models that should be cross-linked depend upon the team’s workflow. Typical examples might include:
- Architectural/Structural: The structural engineer uses Copy/Monitor mode to monitor changes made to the base architectural model. The architect can then use Interference Check to verify that architectural elements are not conflicting with structural components.
- Architectural/Mechanical: The MEP engineer monitors the architect’s changes to rooms and levels, which bound the heating and cooling zones. The architect can link the MEP model to show mechanical system elements in the context of the architectural elements.
- Structural/Mechanical: In this case, both designers benefit from interference detection to avoid potential collisions and conflicts between structural and MEP system elements.
Using this model cross-linking feature, design teams can review, monitor, and coordinate the changes made by all members of the design team. This approach enables model coordination review and interference checking to occur earlier and more quickly, which allows these essential steps to be completed regularly as part of an iterative design process.
Step 4: Iterate and Improve Designs
Steps 2 and 3 should be completed often and repeated regularly as part of an iterative design process. As a design matures and continues to adapt and respond to the requirements and opportunities realized by all the project disciplines, the entire project team can be updated with the latest version of the integrated project model.
Using these updates, they can continue to advance and refine their individual designs in their own models, always in coordination with the integrated model.
This efficient process enables the entire design team to participate in assessing proposed design options and contribute their insights to help the project team find optimal design choices based on broader multidisciplinary considerations.