ArchiCAD Insights: Building Information Model Perspective15 Jul, 2005 By: F. Rutson Fuqua Cadalyst
3D computer modeling saves time and money for all levels of design and construction
"For life - which is in any way worthy, is like ascending a mountain. When you have climbed to the first shoulder of the hill, you find another rise above you, and that achieved there is another and another still, and yet another peak, and the height to be achieved seems infinity: but you find as you ascend that the air becomes purer and more bracing, that the clouds gather more frequently below than above, that the sun is warmer than before and that you not only get a clearer view of Heaven, but that you gain a wider view of earth, and that your horizon is perpetually growing larger." Endicott Peabody -- Headmaster, Groton School, Groton, Massachusetts, October 15, 1900.
Successfully navigating the demands of today's building and design business is quite similar to Peabody's perspective. A dedicated professional works diligently to master his trade along with mastering the ever advancing tools of technology. He strives to produce a product that is worthy of collecting a fee only to find that a new challenge exists the next day and the day after that, to infinity. If we choose to ascend the steep hill of learning and understanding, we gain a broader view of the possibilities that new technology offers. But we must wholeheartedly pursue all that we can take hold of. The process with the computer is just like a mirror; the quality and depth of the information that is entered is returned to the user in the identical proportion.
In the truest sense, the building information model (BIM) is a concept as old as the earliest drawings of the cave man. A drawing or model in any medium that depicts a real element qualifies to be a BIM. What is drastically different today, however, is the functionality that CAD software offers us. That differentiation is the software's ability to list, analyze, quantify, manipulate and view the resultant data in infinite ways instantaneously and with 100% accuracy relative to the CAD drawing that it came from. The advance of CAD interoperability is analogous to the time that the world switched from a Big Chief tablet to an adding machine to perform mathematical functions. It is critical to note that CAD no more gives anyone the ability to design a house than the adding machine gives anyone the ability to do trigonometry.
The Value of a 3D Model
As with the adding machine, CAD has improved greatly over the last decade. An adding machine and CAD are used for a very similar purpose. Enter a number or a CAD element one time, and then use that information to analyze, quantify and compare the data in a multitude of ways. The obvious advantage is that the operator only has to correctly make one entry for many uses. Elements in a 3D drawing can be represented in plan view, section or elevation. Each element is drawn only once, but the element can be viewed and evaluated many ways. CAD supports data extraction in both 2D and 3D, but by far the most dependable information is obtained from 3D drawings. 3D drawings are more valuable because they are directly linked to each other. The plan, section and elevation are derived from the same set of elements. The user also can properly position in real 3D space to provide additional data to each element, since the drawing is in actuality a simulation of the building project.
The following three images are of a project modeled in ArchiCAD.
Figure 1. A shaded view.
Figure 2. A construction photo of work in progress.
Figure 3. A grouping of sections, elevations and plan views.
The information in figures 1 and 3 is produced directly from the model. On this project, drawing elements were used as shop drawings for construction items. This is the first complete 3D model produced by J Wilson Fuqua & Associates Architects. As a result it was also the first project administered through the office that progressed without a single problem. All elements were modeled in 3D space based on a site survey and topographic survey.
We extracted the drawing element information in this model to Microsoft Excel and then to a Microsoft Access database to display quantities for the general contractor, the subcontractors and the vendors. When we sent quantity information to the supplier of moldings for this project, the vendor asked if receiving the quantities was okay. He thought that getting the answer was cheating! Providing quantities eliminates waste in the construction process and produces more dependable quotes in the bidding and pricing process.
The data extraction process with ArchiCAD is very intuitive. An element is created in the model. That element possesses automatic properties such as length, width, volume, material, location and an ID number. Automatic properties are created by merely drawing the elements in the model. You can add additional information such as vendor, cost, etc., to the automatic properties. All of the properties of the elements are extracted from the model by creating a schedule (listing). This extracted schedule can be printed directly on the drawing documents and/or exported to Microsoft Excel. If you want to analyze and sort the data in multiple ways, the data is exported from Excel (or linked) to a database.
Creating a door hardware schedule is an example of sorting and manipulating the element information through a database. On the project shown above, a door list was extracted from the model to Excel. Each door in the model had automatic properties that defined its room location, height, width, thickness, swing plus an assembly designation for the required hardware. The database contains a table that defines all of the hardware (hinges, finials, latches, knobs, door stops, finish, manufacturer and model number) for each assembly designation. An unlimited number of reports can be produced with the information extracted in the door list -- the same set of information produces many different possible forms of representation.
Listing Hardware Components
One such report listed each door opening with all of its hardware components. An additional report listed the hardware sorted by manufacturer. Yet another report summed all hardware and produced a total price for the entire hardware package. During a typical project, there are often changes. In this example, if items in an assembly are changed, the changes are reflected throughout the database, and the reports are reprinted. If an assembly type for a door is changed to another assembly type, that change is made in the model, the schedule is re-extracted and reports are run again. The benefit of this procedure is that with any change, the resulting reports are complete and correct. The model and resultant data eliminate the manual process of counting the hundreds of items that need to be ordered. The reports form documentation for the owner demonstrating that he is getting exactly what he wants. If the budget is strained, the methodology is available to make changes to get the cost and budget in line.
Over 30 years, I have manually wrestled with many hardware schedules. The automatic hardware schedule alone is reason enough to use the virtual model. Recently, I visited a colleague at his place of business and witnessed their process of manually creating the hardware schedule. It gave me the chills to see the hundreds of places for possible errors -- each number or text entry is a potential error waiting to happen.
After producing construction documents via 3D models for more than five years, I simply cannot imagine doing it any other way. All construction issues are solved in the computer simulation process instead of on the job. The model can be viewed and evaluated from every possible angle. Extracted quantities allow building and design decisions to be based on merit and choice, not salesmanship, and the extracted quantities eliminate waste. I foresee that builders, developers and subcontractors will begin to use this modeling technology during the construction phase. I also foresee the surveying profession becoming a more important part of the process with digital staking of all major elements and digital mapping of as-builts added to the model during the construction process. In addition, owners will have the ability to use the model to maintain the property after construction.