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Oglevee showed Hillier architects an early version and explained the thought process behind the parametric change engine. He told them he thought the vision of a single building model would come to fruition with this new software. Hillier signed on as an early adopter of Revit to help steer its future development.

Why Revit is Different

Revit Technology Corporation has revolutionized the way buildings are designed, constructed and operated throughout their lifecycle by inventing what they say is the first parametric building modeler.

The key to the success of this software is that it was designed from the beginning as a parametric modeler. This technology gives building design elements the "intelligence" necessary for them to understand both their own properties and how they should relate to the rest of the design.

Design elements can be physical components such as walls, windows, or roofs, but they also include plans, elevations, sections, dimensions, and even drawing sheets, schedules, and renderings.

A parametric change engine is necessary to provide the context for these components to be assembled into a cohesive design. That change engine must be able to handle the effect of a single change in very large buildings.

For example, a parametric wall "understands" its relationship to other elements. The wall might have a fixed height, or it might extend up to the next story, or it might be attached to the roof. This design intent is captured in the element. This allows a change in the roof to affect the wall. This, in turn, will affect plans, elevations, sections, schedules, dimensions, and other elements.

Ritger says that Revit stands out as the only AEC software tool that can promulgate a change throughout a 3D model from any view of the building. With more traditional CAD software, you must rework the model to successfully publish any drawing updates.

With Revit you can make a data change in a schedule or a graphic change in a drawing layout view, and all references to that item are changed everywhere. There is no need to publish a new set of updated files.

Also significant in the way the changes are executed is the fact that there is no way to accidentally damage a model with 2D commands as is possible with other software, and there is none of the performance penalty one incurs for referencing graphics in other files.

With other CAD programs, says Ritger, the "smart doors" can't cut holes in "smart partitions" unless these objects reside in the same DWG file, and that's a big drawback.

Ritger believes that Revit eliminates many errors due to inconsistencies. For instance, it cannot happen that a vertical shaft is located slightly differently on different floors, or that a door is shown as a left hand swing in plan yet listed as a right hand swing on the schedule.

Revit can streamline huge changes. For instance, it can bring the face of a 12-story building farther back from the property line by a half inch when you are a day away from completing your construction document set. The change will ripple automatically through every wall, window, room dimension, and structural bay.

Revit at Work in Practice

In the Newark office of Hillier, Howard Davis is project manager for the Commercial Realty & Resources Corporation (CRRC) building, a two-story, 40,000-square-foot (3700-square-meter) office building located in Wall, New Jersey.

The project, whose scope consists of designing and documenting both the interior and exterior, is similar to other projects Hillier has done for the same client. Therefore the firm was familiar with the systems and materials, which Davis said made this project ideal for a Revit beta test.

Davis said that in the beginning, a Revit representative visited the Hillier-Newark office, and within six hours they were able to produce floor plans, elevations, and most importantly, several 3D design studies.

During the next few weeks, the training was continued online, via Revit's Web site. As the project documentation grew, Davis became more impressed with the power of this software.

Recent Developments

Revit began volume shipments of Revit's first release in April, 2000 and was well received when exhibiting the product at the American Institute of Architects national convention last year.

Today Revit is in its third release, with over 500 architecture firms subscribing. In the recently released version 3.0, Revit introduces "worksets," which extend the software's multi-user functionality.

Worksets allow team members to work simultaneously on separate sections of a single building model. Team members can view the entire model, but individuals can edit only components within worksets they have "checked out" of the shared model. Changes can be saved on the fly and are available to other team members when the workset is returned to the shared model.

Revit also introduces in its new release the concept of 4D, or time-related properties. Components can now be associated with construction phases and be related to each other over time intervals.

The construction and demolition of any component can be recorded in a phase, and multiple generations of phased construction documents can be created from the single parametric model.

For existing structures, multiple generations of renovations can be recorded sequentially in one model. Phasing information maintained in the model over successive renovations can form a record of work done over the life of a facility.

Phasing information is also included in all of the exported file formats for communication among team members, regardless of the software platforms they use.

The Subscription Model

Revit Technology has implemented an Internet and e-commerce-based subscription model that eliminates high initial costs for its clients. The company has also made innovative use of the Internet in marketing, sales, training, and client service.

Revit is available by subscription on a month-to-month basis with prepayment discounts for longer terms. With quantity discounts available starting with as few as two seats, subscribers have access to all upgrades, instructor-led Internet-based training, customer support, and maintenance.

Current subscribers can download the product and subsequent releases and upgrades via the Internet.

Revit release 3.0 provides support for metric projects, including thousands of metric components and British-standard layering for export to legacy CAD systems. Help text and menus in Revit 3.0 are in U.S. English, and, in April 2001, Revit 3.1 will provide UK/International menus and help text.

This remarkable product has much to offer the AEC world in its approach to design, marketing, sales, and support. With a carefully planned expansion program, Revit's world will soon be international.

Elizabeth Bollinger is a professor at the Gerald D. Hines College of Architecture, University of Houston, in Houston, Texas.

The CRRC model rendered to study the interior lobby area. Image: The Hillier Group The latest release of Revit improves the system's support for 2D construction drawings. Image: Revit Technology Corporation With worksets, multiple users can work on a model simultaneously without problems with version control. Image: Revit Technology Corporation Within Revit, plans, sections, and renderings are all views on the same parametric model. Image: Revit Technology Corporation A hidden-line view of Hillier's 3D model created for studying the CRRC building's interior office layout. Image: The Hillier Group The CRRC building model partially rendered to study the exterior. Image: The Hillier Group A hidden-line view of the CRRC exterior. Image: The Hillier Group A partially rendered model for studying the CRRC building's exterior entrance. Image: The Hillier Group   Click on thumbnail images to view full-size pictures.