Building Information Modelling -A Primer

After years of development and experimentation in the marketplace, the use of Building Information Modelling (BIM) is becoming the norm in the building design industry. Conferences and seminars on the topic of BIM are frequent, and the majority of industry players are seeking to leverage their knowledge and expertise in this rapidly developing area. The term BIM itself has become symbolic of the application of new technology and it is bringing swift transformations in how projects are designed and delivered.

What is BIM? It is a digital process that the American Institute of Architects defines as, “a model-based technology linked with a database of project information.” It can be thought of as a building design and documentation methodology characterized by the creation and use of coordinated, internally consistent, computable information describing a building project in the design, construction and post-construction stages.

In simple terms, whereas building designers are used to working with 2D and 3D computer models, BIM entails a 7-dimensional process. The 3-D modeling process extends to scheduling and sequencing (4-D), cost-estimating (5-D), sustainable design, also termed Green BIM (6-D), and facil- ity management (7-D).

BIM is a new approach depending on a collaborative team vision. It is a unique opportunity for the building industry to have a shared model — a model that incorporates all the various building components, including the building’s geometry, its spatial relationships, and its material properties and quantities. BIM also incorporates the information pertaining to the building services and equipment necessary for the full life cycle management of the facility.

Currently, there are four fully equipped BIM tools: ArchiCAD, Bentley Systems, Revit and Digital Project, supported by fabrication level tools such as Tekla structures and StruCAD. Autodesk coined the term “BIM” when introducing the software Revit Architecture in 1997, which is currently in its 29th release.

To the layperson, the use of BIM adds a new and exciting dimension to the building industry. Detailed graphic models allow a building to be viewed before construction has even started. For the building team, BIM presents a new methodology with technical aspects to master, and new ways for teams to collaborate and communicate.

There may be impediments and imperfections to attain

this fully integrated model at this time, but its imminent advent cannot be denied. Those who do not adopt this technology now shall be left behind.

How BIM Developed

For decades the aerospace, marine and automotive industries have used 3D modelling to design and produce their complex products in virtual space in close co-operation with their production teams. These models were subsequently used for product fabrication. The technology always entailed the initial construction of the model in a 3-D environment, optimizing and coordinating all aspects of the design prior to the final fabrication using techniques linked directly to that 3-D model.

Though architects and engineers routinely use 3-D modelling, the concept of creating a single, virtual coordinated model was originally not appealing to the building industry. The industry considered that, unlike automobiles and similar industrial products, each building is unique, and as a result its design and construction processes are different to those used for mass production. The virtual simulation of the design, construction and performance of a building prior to the physical construction was some distance away. With the advent of the BIM concept and tools, however, each individual building can now be conceptualized, constructed in virtual space, and appraised for coordination among the various disciplines well before the start of the on-site construction.

BIM’s importance for the construction industry

At the core of BIM lies a computable digital database in which objects, spaces and facility characters are all defined and stored. Digital data is not necessarily computable data. As an analogy, Microsoft Word processes, stores and displays information as digital data, but the data is non-computable compared to similar data in a Microsoft Excel spreadsheet. Traditionally, the building industry has dealt with non-computable digital data, everything from the CAD drawings prepared by

the consultant team, to the project scheduling information prepared for use by the constructors.

With the advent of BIM, this previously fragmented set of unintelligent data is cast into an integrated 3-D intelligent model. The model is accessible to, and understandable by, all trades and consultants. Using a BIM editor such as Revit or Bentley Systems, the design team, the construction team and others add their respective data directly, sharing and interacting with others.

With complete architectural, structural, electrical and mechanical systems all defined in one model, the relative position of the various elements and interferences can be detected and coordinated during design rather than at the construction stage. The model is intelligent and the elements are “live” resulting in section and elevation information being available at the click of a button.

Some of the more general benefits of BIM are:

• it provides freedom for the design team to interact directly in 3-D space. The tedious method of working with inert 2-D representations becomes a visual process working with “live” pictorial representations of the structure, building systems and architecture;

• it facilitates the tracking of changes made by different design team members;

• conflicts between different elements of a building are detected at this model development stage;

• it gives design time efficiencies by enabling the transfer and integration of information between the different design disciplines;

• it facilitates the transfer of information for computer numerical controlled (CNC) fabrication of timber structural members.

BIM implementation –the impediments

The adoption of BIM has not been without obstacles. The success of the technology hinges on the transfer of data among various applications and disciplines. Unfortunately, this has not always been seamless. Model overwrites and file transfers often resulted in truncated data or system crashes. Application software, such as that required for structural analysis and BIM software, often did not act in unison. Over time, the interoperability and compatibility of the software has improved. However industry-wide BIM standards are still not fully defined and the multiple BIM products do not yet have the ability to communicate seamlessly with each another.

Fear of change has also been a major impediment, partly because there are still questions related to the ownership of, and responsibility for, the BIM models.

The requirement for collaboration between all parties in the development of the BIM master model is a deviation from current business practices where individual disciplines have traditionally developed and protected the integrity of their own information. BIM methods require new definitions of the responsibilities and liabilities of individual parties. And as all the consulting trades ideally use the same BIM model to input, manipulate and extract information, the legal ownership of the collaborative digital model is not definable. Further, since the model is intended to mimic the actual building in virtual space, it can be used directly by third parties such as steel fabricators and other sub trades, resulting in further questions on legal liability, ownership and responsibility.

The implementation of BIM involves extra initial costs to purchase hardware, in training personnel, and in developing office procedures. The benefits of BIM can result in cost savings, however, as better-defined contract documents reduce changes and extras during the
construction phase. How these impacts affect the cost of the services provided has still to be fully determined by the design community.

The wave of the future

Never before have the various stakeholders of our fragmented industry been promised an information model that is a digital representation of the physical and functional characteristics of a facility. At the same time, building owners have never had the luxury of such a comprehensive tool to form a reliable basis for decision-making during the complete life-cycle of their facilities. Because BIM can eliminate many of the inefficiencies of current construction practices and improve the transfer of information during all phases of a building’s life, its full adoption is only a matter of time.

This is the first in a series of articles that will delve into Halcrow Yolles’ seven year experience, trials and successes, in incorporating BIM processes and technologies into its business operations.

Agha Hasan, P. Eng., is a principal with Halcrow Yolles located in the firm’s Toronto office. Specializing in wind and seismic engineering, structural dynamics and tall buildings, Hasan has been instrumental in implementing BIM into the firm’s design culture.