Building Information Modeling Moves into AEC Mainstream, Adding Value to Project Delivery Process

As Patrick MacLeamy, the Chief Executive Officer of HOK International Ltd. comments in his article “Building A Revolution: The Architect as Master Information Manager”: “Buildings are made up of three-dimensional objects with height, width, and length. Yet architects traditionally have communicated with contractors by drawing these buildings on two-dimensional screens or pieces of paper. All the floor plans, building sections, elevations, and details we show the contractor basically are invented systems for portraying three-dimensional objects on two-dimensional surfaces. This has to change.”

Similar to the revolutionary change CAD/CAM (computer aided design/computer aided manufacturing) brought to manufacturing in the 1980s, BIM is a disruptive innovation driving change now for AEC; it is pushing firms to rethink and transform their business behaviour to reap its benefits. BIM has the potential to integrate AEC project delivery processes horizontally and vertically, enabling building owners, designers and contractors to collaborate effectively and share information concurrently.

Horizontal integration will occur through collaboration and development of re-useable and shareable project information models across the building life-cycle, including feasibility planning, programming, architectural design, construction, facility management and disposal. Vertical integration will occur through collaboration and development of re-useable and shareable information models that represent building assemblies and systems through the process of design and production, for example structural steel engineering, detailed design, fabrication, and installation.

Rethinking AEC Processes
Given the historically fragmented nature of the industry, many firms understand that achieving the potential of BIM requires business process re-engineering. Firms are experimenting with shifting project roles, responsibilities, and risk allocation. They are forming new business relationships that exploit technical collaboration opportunities and improve offerings to customers. And to compete, firms must grapple with enterprise technology and skills training, while maintaining focus on core competencies.

These business factors, perhaps more than current technical capabilities and limitations of BIM, position it at a relatively early phase of implementation for AEC. Nonetheless, there are tangible productivity and service offering benefits now. Firms that acknowledge the inherent problems of design-bid-build are adopting collaborative, concurrent VDC methods, and it is moving into the mainstream of AEC practice.

In March 2007, DPR Construction, a forward thinking national general contractor and construction manager with annual revenues in excess of $1B, completed a 250,000 sq. ft., three story medical office building and 420,000 sq. ft. concrete parking structure designed by Hawley, Petersen, & Snyder Architects for Camino Medical Group (CMG) in Mountain View, CA. CMG is a division of Palo Alto Medical Foundation, an affiliate of Sutter Health. The fast-track $98M project was typical for the health-care market, involving intricate medical gas systems, extensive MEP and fire protection systems, and stringent California regulatory and seismic requirements for acute-care facilities. It was awarded the 2007 Integrated Practice award by the San Francisco American Institute of Architects (AIA).

DPR, sub-contractors, and vendors modelled design construction processes in 3D and 4D (3D + schedule to simulate construction activities and analyse construction sequencing) before beginning construction, and set up a collaborative job-site work environment, the “Big Room”, in which DPR and subs worked side by side to model in 3D, analyse, and resolve conflicts before work occurred in the field. Given accurate 3D models and collaboration to resolve conflicts, MEP contractors had the confidence to prefabricate MEP assemblies with little or no risk and deliver them just-in-time to the job site.

The combination of BIM and lean processes produced stunning results. For $415,000 additional cost in architectural and engineering modelling and the focus on collaboration at the job site, DPR determined that $9M and six months were saved over traditional design-bid-build project delivery. According to DPR representatives Dean Reed, Atul Khanzode, and Blake W. Dilsworth, S.E. in the November 2007 edition of Modern Steel Construction:

Normally, on comparable projects, an estimated 100 to 200 conflicts must be resolved in the field using traditional coordination methods.

According to Mr. Reed, “What we’re doing now is just the tip of the iceberg. We have a lot more information in the dimensional layout than we are using, and the next step is to really drive what we have learned further into the construction process and the facility’s life beyond the project. This is how we as an industry—owners, architects, subcontractors, general contractors—should be building buildings in the future.”

An Overview of BIM Models, Tools, and Processes
The term ‘BIM’ encompasses digital AEC domain models, modelling and analysis tools, and concurrent design and engineering processes enabled by sharing and coordinating such models.

BIM is a digital three-dimensional model of the structures, products and materials that comprise a building project that is created in a BIM authoring system. It contains Virtual Products, two-dimensional and three-dimensional shapes that represent physical products and assemblies installed in buildings such as doors and walls, and other kinds of modelled elements including spaces and rooms, which are defined by geometry parameters and rules.

A BIM is structured, which means it is defined according to a schema that allows a computer program to interpret and reason about it. The schema includes categories and names that classify and identify Virtual Products using AEC specific terms, property sets that describe Virtual Product performance characteristics and semantic relationships that describe dependencies between them. For example a partition wall has openings and contains studs. Virtual Product property sets contain data for multiple design and engineering disciplines, and thereby enable multi-disciplinary analysis. A Virtual Product also has behaviours, where behaviour includes parametric editing capabilities for shapes (pre-defined in a BIM authoring system) and domain behaviour; the functional, predicted, and actual performance of a modelled product installed in a project.

Virtual Products may also reference information and applications from sources external to a CAD system, for example a specification authoring system, manufacturer product information, or a product configurator. The three-dimensional geometry of a BIM becomes an index to multi-disciplinary model views that are specific to design and engineering analyses. This characteristic implies that a BIM can explicitly represent or reference information that is useful in different contexts and applications across the project delivery and facility maintenance life-cycle.

Over time, the knowledge encoded in Virtual Products will become a strategic asset. They will represent best-practice knowledge as firms incrementally improve and annotate them with information from project use and experiences. Errors and omissions risk will decease as firms realise success developing and using high quality models, proven in their previous use.

Many CAD vendors now offer strong BIM authoring systems (Autodesk Revit, Bentley Architecture, Graphisoft ArchiCAD, Dassault Digital Project), which may be described as “3D, object-oriented, AEC-specific CAD” according to sources on Wikipedia. Each of these tools supports powerful three-dimensional parametric modelling. Bi-directional association between model elements and model views is a key feature of parametric modellers. Changing the design from any model view triggers an evaluation of parameters and rules for dependent shapes, thereby eliminating redundant work to update and coordinate documents, for instance plans, sections, and elevations. BIM is a key enabler for:

More broadly, BIM will be an enabler for sustainability analysis that incorporates solar, thermal, lighting, shadows and shading, energy and building regulations, acoustics, air flow, productivity, waste reduction during construction, and life-cycle cost, and resource consumption.

Looking Forward: Quantity Survey, Estimating, and Fabrication
Emergent tools bridge the design intent representation of BIM modelling systems like Revit and ArchiCAD with more detailed models for detailed quantity survey cost estimating, and construction planning.

Reed Construction Data (RCD), a division of Reed Business Information N. A. is dedicated to advancement of Building Information Modeling, from 3D design visualization to engineering analysis and simulation that incorporates building product information. Through its recent acquisition of Tectonic Partners, Inc., RCD is developing frameworks and applications that manage BIM content, automate industry-strength quantity survey, facilitate decision-making for product procurement with respect to quality, energy efficiency, sustainability, and availability, and collect and publish market data for building product demand forecasting.

RCD believes high quality, need-specific, and re-usable Virtual Product content will be an enabling factor for successful BIM-based projects and use of BIM downstream of design.

BIM Library Manager© (BLM), released in May 2007, targets firm-specific Autodesk® Revit® Component and System Family management. The product addresses Revit content management problems encountered by design, engineering and construction firms. Currently, the file system is the predominant tool for organizing and finding Revit families. The kernel of Library Manager is an extensible platform that eventually will collect, unify, and manage Virtual Products, Revit families plus information from multiple sources, and interact with or incorporate different kinds of AEC applications and analysis tools that can be delivered as plug-ins using standard Internet computing protocols.

BLM ships with a library of Virtual Products developed by RCD. These parametric family models are designed for quality, re-use across projects, and utility for design representation and ‘count ability’ for quantity take-off. BLM subscribers will have the option to receive regular updates and additions of generic and manufacturer specific Virtual Products.

RCD is also developing a project Quantity Survey (QS) plug-in that extends the BIM Library Manager kernel. RCD QS extends the metaphor of a Library from manager of Revit Family files in the file system, to manager of Virtual Product instances placed in a Building Information Model with links to other RCD assets, including RS Means assembly and line item unit costs.

Conclusion
BIM affords accurate three-dimensional design intent representation, ease of modelling, lower cost to change design, and earlier and better analytical feedback. These abilities force a rethinking of project delivery from the historical ‘waterfall’ process to Virtual Design and Construction processes, and supports improved decision-making for design, construction, sustainability and eventually product procurement.