Building Information Modeling (BIM) software is a big deal for green building on several levels. Through BIM, the collaborative design approach, often encouraged by green building supporters, is not only possible, but practical. Early CAD software started the process. BIM made (3D) easier, added time and cost properties, linked data to objects, and provides access to a central database.
Building Information Modeling (BIM) software is a big deal for green building on several levels. Through BIM, the collaborative design approach, often encouraged by green building supporters, is not only possible, but practical. Early CAD software started the process, revolutionizing design and drafting by replacing the traditional pencil on paper with more efficient electronic designing and drafting. Three dimensional renderings were possible, but involved extra steps; therefore, CAD was primarily used for two dimensional drawings (2D). BIM made it easier to design in three dimensions (3D). The addition of time properties (4D) brought construction sequencing and scheduling capabilities. Adding cost properties (5D) brought estimating capabilities. Linking data to objects in the drawings added even more intelligence, which allowed not only visual simulation of the construction process, but also simulation of energy use and lighting properties. Although legal issues still need to be worked out, the central database on BIM-based projects allows all team players to share the same information, eliminating inconsistencies and duplication of effort. Team access to the central database also helps in the coordination of any issues that arise during construction. Without BIM, sharing information is possible but difficult, as there is no central database.
There is virtually no limit to the information that can be associated with objects included in a BIM model. Information such as distance from a manufacturing source, environmental life cycle properties, and reused material content allows architects, engineers, and consultants to determine percentages. Cost and content percentages can be calculated based on individual components, systems, and the entire building. For estimators, quantity take-off reports can be generated from the BIM model, eliminating time consuming manual counting and measuring. The report can be used directly, or imported into construction cost estimating software or spreadsheets.
Software packages that apply the BIM concept include Autodesk Revit Architecture (www.usa.autodesk.com), Autodesk Green Building Studio, Autodesk Ecotect Analysis (www.autodesk.com/ecotect/ analysis), and others. Some of the packages are developed mainly as design tools while others are more of analysis tools focusing on daylight analysis, acoustical analysis, thermal comfort analysis, energy analysis, and other aspects of building functions. Pricing of these packages varies and so does the learning curve.
BIM does require a substantial investment in time and money. However, as in CAD, “reader” programs are available for those that only need to view, measure, or review BIM files. For preliminary building modeling, Google offers a free easy-to-use program called SketchUp. A version with more features and capabilities is available for $500. Programs from other sources, called “plugins,” are available that expand the capabilities of the software, including those that allow modeling of energy usage, lighting characteristics, and total carbon footprint. Open Studio is a free plugin for SketchUp provided by the U.S. Department of Energy, that simplifies the creation and editing of building geometry for its EnergyPlus . Integrated Environmental Solutions (www.iesve.com) and Greenspace Research (www.greenspaceresearch. com) also offer free plugins for SketchUp, as well as integrated building performance analysis tools for a fee.
For Estimators, quantity take-off (QTO) software tools permit efficient extraction material quantities from the BIM model into a report, or exportation into estimating software or even electronic spreadsheets. The Reed SmartBIM QTO (www.reedconstructiondata.com/bim) also links materials being taken off to the RSMeans CostWorks database, while multiplying the quantities by the unit costs. Of course, both quantities can be refined by the cost estimator. The software costs about
$500 per user.
Adapted from Green Building: Project Planning & Cost Estimating, 3rd Edition, available through RSMeans.