• Maintenance of the building, including its systems and equipment;
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• Management of equipment and building specification information;
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• Energy use, including ongoing monitoring;
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• Security systems;
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• Tenant needs.
As with the earlier phases, the occupancy team members will continue to rely on open standards to ensure that data can be interchanged between the database and other team applications.
5.8 Workflow
BIM programs are implemented to develop a workflow that will make the product meet quality standards and revenue targets. Businesses in the AEC/FM industry are all looking to enhance their bottom lines by improving their profit. To accomplish this, businesses look at refining their productivity, increasing the quality of their work, and streamlining their processes to minimize production and costs that oth-erwise reduce their profit margins.
Section 5.9 examines the change in workflow when utilizing BIM technology.
The new component of the BIM workflow is the creation and maintenance of the single database shared throughout the life cycle of a project. One primary question is who will be maintaining the BIM database. From planning through construction, the database is typically managed by the phase leader; for example, during design, the architect would manage the project database. Once the period of occupancy begins (with many repeated design and redesign cycles), who maintains and is re-sponsible for the database must be resolved.
5.9 Changes in Workflow using BIM
The primary impact of implementing BIM is the shift in which the work effort will occur in the process. For example, for architects, traditionally the work and billing were divided so that the schematic design (SD) phase comprised 15% of the work, design development (DD) 30%, and construction documentation (CD), which in-cludes specifications, 50%, and bidding, 5%. As we saw in Chapter 2, using BIM, this is changing.
52 The BIM Process
5.9.1 Schematic Design
The schematic design phase is now approaching 30% of worktime for the architect.
This reflects the creation of the 3-D virtual model in a BIM-capable application such as ArchiCAD, MicroStation, or Revit. The purpose of this phase is to decide on a design approach. The process has the architect typically presenting two or three alternative schemes. Previously, each scheme was presented showing concep-tual 2-D plans, sections, and elevations supplemented with one or more perspective views; the minimal representation to communicate the ideas. This minimized the effort necessary to produce the work and was therefore less costly. Now, using CAD applications, the entire building is modeled, at a schematic level, for each scheme. It is initially more time-intensive than creating the few drawings, but is necessary by the nature of working in a virtual model environment.
An added benefit of creating the entire building and site is that the architect is required to think through his or her entire design. The complete building is de-scribed, not selected elements, and hence the increased percentage of the overall work for this phase.
5.9.1.1 Project Data
Project-related information is now embedded in the project database and can be included in the virtual model that the architect creates. As discussed in earlier chap-ters, the relevant information is more quickly amassed. Different than before, the BIM database that evolves throughout a project’s entire life cycle requires that data be entered only once and then be available henceforth to all team members.
5.9.1.2 Choices
More informed decisions can be made based on results from analysis applications including project considerations of energy, cost, code compliance, and structural alternatives as this information is derived directly from the virtual model even at this schematic design level.
5.9.1.3 Virtual Building
The virtual model of the project created by the architect and engineers provides a more complete view of the entire project for all schemes presented. The consultant engineers and landscape architects are also creating schematic-level designs for each of the architect’s design schemes. Another benefit is that the virtual models of all the disciplines combined or superimposed into one model can be accurately analyzed for how well the systems work together, the design aesthetic, the meeting of the program goals, and the ongoing cost estimates, energy, and applicable codes.
5.9.2 Design Development
Design development is now approaching 40% of the work. The model created dur-ing the schematic phase is now used for developdur-ing the design. There is no waste or duplication of effort redrawing or remodeling. Any nondesign information that
5.9 Changes in Workflow using BIM 53 had been embedded in the CAD model file would have to be remembered and then embedded into a new model.
Construction documents are now reduced to 25% of the work; previously, this set of documents was 50% of the work. Using BIM, data that is gathered early in the design process can be incorporated in the database. Only the appropriate infor-mation for each phase is shown in the documents for that phase. Using BIM, the work effort during construction documents is now about 25% of the total work effort. The need to redraft all the work is gone. The data gathered for the project is already included in the database even when it was not shown earlier. To resolve the design in a virtual model, many of the decisions and implications of systems and components being considered were resolved in the early design stages. The periods of construction documentation and specification concentrate on finalizing the detail-level decisions.
5.9.2.1 Bid Documents
Preparing the work for bid is a negligible change in the new work process. Depend-ing on the scale of the project, 5% may be too high, but for purposes of this dis-cussion where we are evaluating change, the precise percentage is not critical. The quality of the information that the contractors now have available upon which to base their bids is where the change is seen.
Responding to requests for clarification of the bid should be less as the BIM bid package is measurably better coordinated.
The virtual models can facilitate the bidding process by providing models that accurately depict the building. They define the building systems and components separately along the same divisions that a contractor’s estimators do:
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• Material quantities and costs;
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• Specifications;
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• FF&E (furnishings, fittings, and equipment);
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• Building systems and their performance requirements;
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• Coordination of trades and building systems;
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• Resolution of clash;
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• Site preparation;
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• Project scheduling both labor and materials;
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When modeling a building in CAD, the rule of thumb is to model it as it will be built. The design continues to be refined as it develops and the virtual model devel-ops along the same lines. For example, we look at a typical floor assembly. During the schematic design, the floor assembly, which includes the finish floor down to
54 The BIM Process the ceiling of the story below, is first modeled as a single slab of the correct overall thickness. Materials are shown as colors representing the typical flooring on the top, the exterior building finish color on the sides, and the ceiling color underneath.
As an initial placeholder, this works well. As the design progresses, the material rep-resentation becomes more realistic (i.e., wood flooring, brick exterior, and painted ceiling). The assembly is broken first into horizontal components of finish floor, subfloor, structure, plenum space, ceiling structure, and ceiling material.
Color Plate 3 shows images from ArchiCAD detailing a floor progressing from a slab to an assembly composition to a component and systems separation of the ceiling, the plenum occupying MEP, the structure, and the ceiling assembly as the design is developed from the concept to construction documentation.
The virtual models that architects and engineers create in their respective pro-grams deveop in their level of detail along with the project design. As discussed throughout this book, the ability to overlay models from these different team mem-bers and analyze them for compatibility has already proved highly cost-effective.
The models, similar to when real 3-D models are built, reflect the level of de-sign. The same is true virtually. In Color Plate 4 we see the evolution of a floor as-sembly from a rectilinear slab into individual components. In the rightmost image the floor assembly includes structural truss members, plenum space, and the begin-nings of ductwork and plumbing systems. This example was modeled in Archicad using the MEP add-on. In Figure 5.4 running the MEP clash-analysis feature, the message that there are no clashes is obtained. In the next example (shown in Figure 5.5) where an HVAC duct is added clearly penetrating the floor assembly, running the clash analysis results in the five clashes noted. In Selection Clash 005 the elements causing the clash (the portion of the duct penetrating the floor) change color, identifying the problem area. The architect can address work with their
Figure 5.4 Clash analysis can be done on the floor assembly to check for objects inhabiting the same space. Previously we saw clash analysis run in Navisworks. Here the clash analysis is being run within ArchiCAD checking the MEP system against the rest of the architect’s model. Here a duct goes through the floor assembly without a floor existing for it.
5.9 Changes in Workflow using BIM 55
consultants to resolve this problem while in design. Resolution of the clash can be tracked as in other clash analysis programs. The Revit suite of programs, owned by Autodesk, include companion architecture, structure, and MEP programs as well as Navisworks, where the models from Revit and other programs can be similarly combined and analyzed for clashes. Color Plate 4 illustrates a similar analysis using Navisworks on a hospital project.
5.9.2.3 Database
One model is evolving throughout the project life cycle as part of the BIM database.
When the construction industry first embraced BIM, few architects were using BIM applications. Contractors foresaw the potential of BIM to more accurately depict projects, which, in turn, would provide them with more accurate data to better control the project costs and scheduling during construction. As the architects were not providing them with virtual models, contractors had the models constructed as part of the cost of the construction work. Vico Software, founded in 2007, began as a part of Graphisoft. ArchiCAD was one of the first applications developed to le-verage project data for contractors. Vico Software has developed their suite of pro-grams to works with the major BIM applications including Revit and MicroStation.
The construction industry embraced BIM, seeing the benefits and recogniz-ing savrecogniz-ings of 30% on projects with a similar reduction to project schedules. A significant part of the savings has been achieved by using applications such as
Figure 5.5 The report shows a total of five clashes. Clash 005 shows the duct intersecting the floor assembly (note different color of duct going through the floor assembly). The resolution of this clash can be tracked similar to Navisworks and clash analysis programs such as Navisworks.
56 The BIM Process Navisworks and Solibri for model checking, particularly for clash analysis. These applications are now being used more routinely during the design phase.
As more architects create BIM models that can be used by contractors, the sav-ings seen during construction will be shifted to the design phase.