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Chapter 1: Understanding BIM: From the Basics to Advanced Realities
In this chapter, we’ll cover the principles of a Building Information Modeling (BIM) approach and summarize how BIM differs from a traditional 2D CAD tool. We’ll explain fundamental character- istics of Revit, how Revit delivers the benefits of a true BIM tool, and why Revit is the tool best suited for a process motivated by an integrated and collaborative practice.
In this chapter, you’ll learn the following:
  • The advantages of Building Information Modeling
  • What to expect from Building Information Modeling

The Advantages of Building Information Modeling

The production of design documents has traditionally been an exercise in drawing lines to repre- sent a building. These documents become instruction sets: an annotated booklet that describes how the building is to be built. The plan, section, and elevation are all skillfully drafted—line by line, drawing by drawing, sheet by sheet. Whether physical or digital, these traditional drawing sets are composed of graphics—each line is part of a larger abstraction meant to convey design intent so that a building can eventually be constructed. By and large, this is still the reality we face today, but the process of creating these drawings is being fundamentally changed as a result of BIM. Let’s put this into a historical context for a moment and briefly walk through the evolution of architectural design and documentation.

A Brief History of Design and Documentation

Andrea Palladio’s Four Books of Architecture (trans. Robert Tavernor and Richard Schofield, MIT Press, 1997) presents an amazing array of drawing techniques that show buildings cut in plan and section and even hybrid drawings that show elevations and sections in one drawing. There are drawings complete with dimensional rules for laying out the relative proportions of rooms. You can even see hints about construction techniques and structural gestures in the form of trusses, arches, and columns.
These representations were simplified expressions of a project, and often they were idealized versions of the building—not necessarily how the building was built. The drawings were commu- nication and documentation tools, themselves works of detailed craftsmanship. In those days (14th–17th centuries), the architect was brought up in the tradition of building and had integral knowledge of how buildings were constructed. Palladio, like many other architects of his day, grew up as a stone mason. Building techniques were deeply embedded in the construction trades, which in turn spawned the great architects of the time. Other master masons and sculptors include the likes of Filippo Brunelleschi, Giovanni Bernini, and Francesco Borromini. These architects are often referred to as the master builders—they were integrated into all facets of the design and construction of architecture.
Over time, however, architecture became more and more academic as building typologies solidified, and classical reconstructions on paper and in model form became part of the formative education of the architect. The design profession began its gradual separation from the building trades. The notion of design process and iterative problem solving became critical attributes of a design pro- fessional—in many cases superseding knowledge of construction means and methods.
With modern architecture, solving abstract spatial problems, accommodating programmatic ele- ments, and experimenting with new materials became driving forces. The machine age and the prom- ise of mass production were idealized and fully embraced. Le Corbusier’s (1887–1965) romantic vision of steamships and automobiles inspiring a new generation of architecture took hold, and buildings became increasingly machine-like. Consider all the office towers and commercial office parks that have emerged, with their internal mechanical systems used to keep the building operational.
As buildings continued to grow in complexity, both technically and programmatically, the architect grew more removed from the act of physical construction. Modern materials such as steel and reinforced concrete became prevalent, and complex building systems were introduced. In turn, the production of more detailed drawings became a legal and practical requirement. Structural engineers and mechanical engineers were added to the process, as specialized knowledge of build- ing systems grew. No longer could the architect expect to produce a few simple drawings and have a building erected. Complexity in building systems demanded greater amounts of information, and this information was delivered in the form of larger and larger construction document sets. Architects today find themselves drafting, producing details, working with a wide range of con- sultants, and still having to create sketches for contractors in the field.
The traditional production of plans, sections, and elevations continues to this day, but with far more drawings than in the days of Palladio. At the same time, we ask: Will all these drawings be necessary in the near future? Will the adoption of BIM lead to new delivery methods, new forms of construction, and new roles for the architect? Can a shift in technology lead to a shift in thinking about building?

Building Information Modeling

Fast-forward to the present context and the advent of Building Information Modeling: In this land- scape, complexity is still very high, but the production of drawings is now the by-product of building a virtual 3D model composed of constructive elements. These elements are loaded with data that describe not only geometry, but also cost, manufacturer, count, and just about any other metadata you can imagine. With an integrated parametric 3D model, it’s possible to detect spatial clashes between the multitudes of systems in the building. You can know with confidence whether duct work will interfere with the structural steel long before construction starts.
The goal of reducing errors and smoothing out the construction process is driving firms to be more efficient, effective, and productive. In this reality plans, sections, and elevations are all derivative representations—producing them isn’t a set of isolated, discontinuous tasks. A data- rich model means that more analysis and iterative searching for optimal solutions can occur early in the design process. As detail is added, the model becomes an increasingly accurate represen- tation of what will actually be built. The model itself can be used to generate part lists, shop draw- ings, and instructions for industrially produced elements. If you can send a digital file that can instruct machines to produce components, the need for traditional annotated drawings disap- pears. Of course, that day has yet to arrive; but the idea can get you thinking about future direc- tions and possibilities. The ultimate benefits of BIM are still emerging in a market primed to radically change the way buildings are designed and built. A shift in process and expectation is happening in the Architecture, Engineering, Construction (AEC) world, with private and public sector owners beginning to demand BIM models as part of the delivery package.
The shift from traditional 2D abstractions to on-demand simulations of building performance, usage, and cost is no longer a futuristic fantasy but a reality. In the age of information-rich digital models, all disciplines involved with a project can share a single database. Architecture, structure, mechanical, infrastructure, and construction can be coordinated in ways never before possible.
Models can now be sent directly to fabrication machines, bypassing the need for traditional shop drawings. Energy analysis can be done at the outset of design, and construction costs are becoming increasingly predictable. These are just a few of the exciting opportunities that a BIM approach offers. Designers and contractors can begin to look at the entire building process, from preliminary design through construction documentation into construction, and rethink how buildings come together. The whole notion of paper-based delivery may become obsolete as more players adopt up-to-date, accurate, digital models.
As we’ve mentioned, with a Revit Building Information Model, a parametric 3D model is used to generate traditional building abstractions such as plans, sections, elevations, details, and schedules. The drawings produced aren’t discrete collections of manually coordinated lines, but interactive rep- resentations of a model. Working in a model-based framework such as Revit guarantees that a change in one view will propagate to all other views of the model. As you shift elements in plan, they change in elevation and section. If you move a level height, all the walls and floors associated with that level update automatically. If you remove a door from your model, it’s simultaneously removed from all other views, and your door schedule is updated. This unprecedented level of coordination allows designers and builders to better control and display information, ensuring higher quality and a leaner process.
The immediate 3D design visualization of the building and its spaces improves understanding of the building and gives you the ability to show a variety of design options to all members of a project, at any moment. Integrated design and documentation keeps the data centralized and coor- dinated. This in turn leads to live and up-to-date schedules and quantity take-offs. That information can then be used to make decisions earlier in the design process, reducing risk and cost overruns. Not only that, but with the coordinated BIM model, you can start running energy analysis, solar studies, daylighting simulations, and egress analysis much earlier in the process, allowing you to iterate through design decisions earlier, not later.
Coordination with BIM is now required for many buildings to come into existence. Consider Daniel Libeskind’s recently completed Denver Art Museum and its extreme geometric configuration (Figure 1.1). Integrating the mechanical and structural systems into a 3D model was essential to the building’s successful completion. Exact spatial organization of structural members could be mod- eled, which in turn led to fewer field errors and fewer requests for information. In addition, parts could be sent directly to fabrication from the model, eliminating the need for 2D drawings entirely.
Figure 1.1
BIM makes it possible to build more complex buildings with fewer errors. Denver Art Museum, Daniel Libeskind
Let’s not leave out some of the more pleasurable aspects of BIM that go beyond all the technical, economic, and ecological benefits. With a 3D model, you can expect to see changes in how you interact with your team and your clients and in the way you produce presentations. No longer are you stuck with using 2D drawings or outsourcing to create perspective images. You’ll find your- self working with your team in close quarters, sharing a model, and exploring it together. With your clients, you can now take them through the building, in full 3D, from the beginning. The experience of working with and visualizing 3D space can’t be overemphasized, and people enjoy it immensely. In the BIM era, 3D experience is the norm, not the exception.