The Benefits of Building Information Modeling
- Mar 17, 2009
By David Demarest, Architecture DemarestFor several years, architectural firms and construction companies have been experimenting with building information modeling (BIM). In the course of experimentation, they have discovered that the application can decrease both design and construction costs. Implementation of BIM technology has passed the experimental phase as designers and builders familiar with the application have begun to promote BIM’s design, construction and economic benefits to owners.In turn, these owners are beginning to experiment with BIM, which also provides cost-saving benefits related to building maintenance, future expansion and renovation throughout a building’s lifetime. In fact, all of BIM’s cost benefits—whether related to design, building, engineering or management—ultimately accrue to owners.What is BIM? How can a single software tool allow owners to save money on so many levels? And with regard to college campuses specifically, how does BIM alter the cost structure of student housing?Building virtual first The BIM application constructs a massive relational database of structure, materials and components in a three-dimensional space. The software virtually models a complete structure down to its smallest components and stores the information in a retrievable database based on quantity and location. The application includes a virtual camera that enables users to “fly” around the virtual model and look at it from any direction For example, in a student housing project, the camera can fly into the front lobby and around the common room. It can ride up in the elevator or march up a flight of stairs. It can check out each of the one-, two- and three-bedroom suites. Unlike two-dimensional computer-aided design (CAD) drawings, which few people–other than architects–can envision as a finished building, a BIM design is easily comprehensible to builders as well as owners.Because a completed BIM design is a virtual model, it is possible to drill down into the model and observe any or all building components, specifications or quantities. A facility manager might, for instance, want to ensure that the HVAC system specified for a residence hall matches up with the structure’s square footage. He can use the virtual camera to run up to the roof, click on the HVAC unit and call up the specifications. The same goes for the roof, foundation, wall systems, windows and any other building system. Bringing down design costsBIM design takes more time and information at the beginning of a project than CAD, but it pays off later in the construction process because BIM makes it easy to analyze costs as the design progresses. With a campus residence hall, an architect might ask the program to test the cost of a brick building skin against stucco and to analyze how the different costs would affect the overall budget. The software can measure the installed square footage of each material and instantly estimate costs that are associated with them.In addition, BIM schematic drawings pack in more details than CAD schematics. Those of a residence hall bathroom, for instance, include a medicine cabinet, vanity and sink with associated wall connectors, plumbing and valves. Instead of a CAD drawing showing the objects’ layout, a BIM model shows perspective and three-dimensional characteristics. Underlying the model are the component specifications. When BIM schematics are complete, they include complete or almost-complete construction drawings, which, in the CAD process, would usually come much later.Moreover, a finished BIM design contains fewer conflicts. For example, in CAD, a beam might inadvertently be set five feet too low, causing it to run through a wall below the ceiling. In some cases, no one will notice until the contractor begins planning the beam, ceiling and walls in that portion of the structure, at which point the situation demands a change order and revised costs. BIM’s three-dimensional features, however, enable the program to detect conflicts and flag them during the design, when changes can be made virtually, not physically.Eliminating construction costsConstruction starts with estimate development and ends when everything is crossed off the punch list. From beginning to end of this process, BIM can streamline and improve construction performance. It automates estimation by keeping running totals of all quantities available on spreadsheets at the push of a button. Each time changes are made and materials are added or subtracted, the system updates the estimates. By eliminating conflicts during design, conditions on the job always meet expectations. Not only does this allow for more cost-saving off-site fabrication, which promotes quality, it also means that BIM jobs typically see fewer change orders.According to “The Contractors’ Guide To BIM,” it enables contractors to carry out “what if” plans. This way, they can select the most appropriate sequencing orders, site logistics, hoisting alternatives, and other staging and scheduling options. Overall, BIM organizes data quickly and accurately and promotes faster, better decisions. The big winners: ownersBIM offers substantial benefits to architects and contractors, enabling them to work better, faster and cheaper. Owners also benefit in the form of higher-quality, lower-cost buildings.The advantages BIM provides to owners don’t stop upon project completion. Owners who power up with a BIM application will find it worthwhile to purchase, as an additional service. At the University of Texas at San Antonio (pictured), for example, the facilities director has decided to investigate, using BIM modeling, updating the existing hand-drawn and CAD as-built drawings of their campus buildings to facilitate property, facilities and maintenance management.An as-built BIM file contains detailed specifications for every structural component, right down to the size of the bolts that anchor the HVAC units to the utility closet floors in residence hall suites. Accurate lists of components and specs make it easy to build an appropriate inventory of filters, lamps and other everyday maintenance needs, while ensuring that orders for replacement components and materials are properly specified.A powerful BIM database can store and track an amazing number of useful details. For example, as long as the original data has been properly entered, BIM can report the brand, style and color of the carpet in every room in a residence hall, including the suites, common areas and the lobbies. The application also stores the room’s purpose—which is important with regard to whether that means the room attracts more or less activity. This affects the selection of replacement carpet. BIM can also produce daily, weekly, monthly and annual maintenance to-do lists, issue reminders and track warranty periods on original and replacement components and materials. By selecting BIM-competent architects and contractors, facility managers can better manage the costs associated with the design and construction phases of campus projects. Acquiring BIM knowledge and learning to use its powerful property management and maintenance capabilities allows managers to alter the cost structure of an entire facilities department—for the better.David Demarest, AIA, is a principal at Architecture Demarest in Dallas. He can be reached at email@example.com.