by Larry Rocha

"What happens to the cost of the building if we add 40 square meters to the lobby?" "What happens to the total height of the building if we use a steel frame instead of a cast-in-place system?" "How will changing the structural system affect the construction schedule?"

Answering these questions during design used to take days or even weeks. Using current technology, some designers are answering them in a matter of minutes or hours. This is because they create an "intelligent" digital model — which combines data and geometry — as a part of their design process. This approach is sometimes referred to as using an "integrated building model," a "virtual building model," a "single building model," or, more recently, a "building information model."

Not Just a Pretty Picture

Designers have long used three-dimensional representations as part of their analysis and communication processes. Three-dimensional computer models have been used since the 1970s. Renderings and massing models are part of many building design projects. In most conventional software systems, these 3D representations of the building are created and maintained separate from, and requiring coordination with, the 2D contract documents, or construction drawings.

Changes to a design always require coordination between the 2D and 3D representations. In conventional systems, it is the designer's responsibility to make the necessary changes to maintain consistency. With integrated models, the 2D and 3D representations come from the same dataset, so the adjustments can be automatic.

By "slicing" a virtual building, the design team can generate 2D "reports" — such as floor plans, elevations, sections — anywhere more study or clarity is needed. With the integrated building model, contract documentation can be smoothly coordinated, evolving representation of the building's design, a byproduct of the design process.   >>>

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The conceptual design and space planning study for a spa, used to explain the layout and to calculate components and costs from an integrated building model. Image: WATG A door, shown in red, appears in many representations which vary by view, but it is a single object within the CAD software. Image: WATG   Click on thumbnail images to view full-size pictures.