Overview — BIM Basics

Key Concepts

Evolution of Design Communications

To appreciate the key features and value introduced by building information modeling (BIM), it is helpful to look back at the history of design communication and how building modeling has been used in that process.

Prior to the Renaissance, building designs were documented and communicated using physical models. These models provided a physical representation of the proposed design that everyone could easily see from many perspectives. To construct a physical model, design features had to be fully understood and resolved in 3D, so the model served many purposes—as a design tool, as a building plan, and as a record of the design.

The use of physical models necessitated a direct style of communicating the proposed design to the people who would execute it. Master builders would interpret the model and explain the key design features and details to the craftspeople charged with building it. And when questions arose, people would return to the master builder and the physical model for guidance.

This method of communicating design intent through physical models relied heavily on the quality and skill of the craftspeople employed. Fine details that could not be seen in the model would be resolved in the field based on the knowledge and experience of the builders.

Eventually, the inefficiencies inherent in relying on physical models to communicate design led to a new, more efficient development—architectural drawings.

Introduction of Architectural Drawings

During the Renaissance, a new system that decomposed a proposed design into a series of related architectural drawings was developed and widely adopted. In this system, a design is described through a series of 2D orthographic projections, which typically include:

  • Plans views showing a design from above. These views often include floor plans showing the layout of rooms and spaces, roof plans, and site plans.
  • Elevations views showing exterior facades. Elevations are also used to show interior details and complement the plan views by documenting the height of key design elements (for example, in kitchens, bathrooms, or spaces with cabinetry).
  • Sections views showing the vertical relationships between building elements and their connection details.

These 2D views are often complemented by 3D drawings showing how the design features resolve in views that are more easily understood by people unfamiliar with architectural drawing conventions. These 3D views can be drawn using several methods—isometrically, axometrically, or as perspective views. However, the effort required to create these 3D views is significant. So they are often created after a design is complete, rather than as a working design tool.

Architectural drawings are used to serve many purposes—as design tools, as building plans, as contract documents, as historical records, and as-built drawings. For many years, they have been used as the primary method for communicating design intent between a project’s designers, owners, builders, reviewers, approvers, and users. But as the number of purposes and uses has increased, the number of architectural drawings that must be produced to fully document a project has also increased dramatically.

Rather than relying on hand-drawing and drafting, a more efficient method for creating architectural drawings was needed. In the late 1980s, the widespread adoption of microcomputers provided a solution, and computer-aided drafting (CAD) transformed the building industry.

Computer-Aided Drafting

The adoption of CAD tools, such as AutoCAD® software, provided a huge leap forward for the building industry. CAD significantly increased the efficiency with which architectural drawings could be produced, while also bringing greater consistency, reusability, and repeatability to the design process.

While the value efficiency gain was enormous, the CAD approach still suffered from a critical weakness that was introduced during the transition to drawings, which relies on 2D abstractions to represent a 3D design. The lines that are used in architectural drawings do not carry any intelligence about the elements they represent. They are just lines, and they can be drawn in ways that do not accurately represent real 3D objects.

While the production of architectural drawings using CAD tools is very efficient, there is no inherent coordination between drawings, conflict checking, or change propagation. CAD drawings can be interlinked or cross-referenced, but each one remains an essentially separate element. Coordination between the lines shown in the drawings is not automatic, and design professionals are responsible for the formidable task of maintaining consistency between the hundreds or even thousands of individual drawings needed on a typical building project. As projects became more complex, design teams grew larger and time schedules became more compressed, demanding a better approach.

Building Information Modeling

The introduction of BIM tools, such as software products based on the Autodesk® Revit® platform, provided a quantum leap forward in our ability to communicate about design with all members of a project team and manage the myriad of details necessary to describe and coordinate the activities involved in designing and constructing a building project.

In a BIM-based workflow, design and construction information from all project participants is stored in a single database (or a series of inter-linked databases that facilitate easy sharing of information about building elements). This sharing of project information enables new workflows that simplify the storing, tracking, and reporting of all building information.

This BIM approach helps eliminate inconsistencies by providing all project team members with the most current information about elements in the design. Changes made by any team member can be synchronized with the central repository, so rather than relying on disparate versions or copies, everyone has access to the current state of the design and the effort required to coordinate the information is drastically reduced.

BIM has not only revolutionized the drawing production process: having access to the information stored in a building model has also created new workflows that are fundamentally changing the way projects are designed, constructed, planned, and analyzed. BIM offers benefits throughout the entire project lifecycle, including:

  • Analysis of structural and energy performance in the design phase
  • Planning, 4D sequencing, and conflict checking in the construction phase
  • Component ordering during the procurement phase
  • 3D printing and machining in the manufacturing phase
  • Facilities management knowledge and updating records of events in the use phase

Several key trends in the building industry are driving the adoption of BIM as an indispensable tool for firms to remain competitive. {/sliders}

Trends Driving BIM Adoption

Several key trends in the building industry are driving the adoption of BIM as an indispensable tool for firms to remain competitive.

Reducing Waste and Paperwork

There is increasing pressure on AEC firms to reduce waste and rework. On-site material waste from inefficient assembly and poor planning represents a large part of a project budget and consumes additional resources for proper disposal. BIM tools enable the detailed design of building elements off-site, increasing the efficiency of material use, assembly, and installation.

BIM facilitates the retention of knowledge and best-practices from one project to the next, thereby reducing wasted effort involved in reinventing project standards. And the transition from a paper-based workflow between functional silos to a BIM model-based workflow helps reduce the number of design errors requiring rework or costly resolution in the field.

BIM can improve coordination between both the project data and the project team members, so errors can be spotted earlier, giving teams the opportunity to act proactively to avoid costly mistakes and waste..

Managing Greater Complexity

Project teams are growing increasingly diverse in response to the increasing complexity of design requirements. Design teams may now include dozens of designers representing disciplines such as energy analysis, electrical design, mechanical systems, information technology, fire protection systems, daylighting, and many more. These multidisciplinary project teams need tools that facilitate better communication and coordination, and BIM has proven to be very effective in this role.

The workflow required by these multidisciplinary teams is also becoming increasingly complex as team members collaborate more and earlier in the project design phase. In paper-based workflows, designers often worked in functional silos with periodic handoffs of printed drawings to share information. This approach is not sufficient for the levels of coordination needed for today’s projects.

BIM provides a vehicle for early and consistent collaboration. Team members can be given access to the current state of the project, even at the earliest steps in the design process. This facilitates early design input from all team members and supports an iterative design approach where the inputs from all team members are considered as the proposed design is evaluated and matures

Working with Compressed Project Schedules

Competitive and economic pressures are driving the time budgeted for projects design and construction to be compressed. Many projects now use a fast-track delivery approach where many design and construction activities are carried on concurrently to bring the facility on line in the shortest time possible.

This fast-track delivery strategy requires project teams to work simultaneously and collaboratively across all disciplines rather than sequentially in silos. The BIM-based workflow allows early participation and information asset sharing by all team members, which improves project delivery time.

Integrated Project Delivery

The benefits of sharing project information between all the participants in the design, procurement, and construction activities on a project are driving major changes in the way teams are being organized for project delivery. This trend is creating a need for new organizations, new risk sharing relationships, and new tools/technology that enable sharing.

The integrated project delivery (IPD) approach includes new practices and workflows as well as new contract types and risk-sharing relationships that enable project team members to focus on the entire building lifecycle and rewards them based on the success of the overall project. IPD requires the involvement of more diverse participants earlier in the design process, and the use of a BIM-based approach is often crucial to its success.

Over the life of the project, BIM brings great advantages that easily outweigh the up-front costs of transitioning to a BIM-based workflow. The adoption of BIM as an integrated approach to coordinate the design, analysis, and construction activities on a project is essential for project teams wanting to remain competitive going forward.