Book Details :
Language English
Pages 308
Format PDF
Size 23.1 MB

 

BIM In Small-Scale Sustainable Design by Francois Levy


 

BIM In Small-Scale Sustainable Design by Francois Levy | PDF Free Download.

BIM Contents


  • BIM and Sustainable Design
  • Design Software
  • Site Analysis 
  • Massing Analysis
  • Solar Geometry and Daylighting
  • Passive Cooling
  • Passive Heating 
  • Onsite Energy Systems 
  • Building Hydrology
  • Materials and Waste 
  • Collaboration

Introduction o BIM In Small-Scale Sustainable Design PDF


Building Information Models and Modeling

Rapid developments in building design and analysis software over the last decade, coupled with advances in desktop and laptop computational power, have led to the emergence of new digital models for the design and documentation of buildings: virtual buildings or building information models (BIM).

Thanks to these advances, BIMauthoring software applications combine three- or four-dimensional models with imbedded, intelligent building objects related to a contextual database.

An inescapable buzzword these days in the practice of architecture (and among other building professionals), BIM may commonly mean both build ing information modeling (the process) and building information model (the digital artifact).

In this book, I use BIM (alone) to refer to the modeling process, whereas the model itself I call somewhat redundantly the BIM model or ArchiCAD’s virtual building.

For example, a BIM column is not merely depicted as a two-dimensional representation of three-dimensional extrusion but exists in the model as an intelligent object that “knows” that it is a column.

Contrast this with a column drawn conventionally in plan: increased line weight and perhaps poché allow the user, thanks to established graphic conventions, to infer the meaning of four lines which are themselves “dumb” (both in the sense of unintelligent and mute).

As a result of BIM’s data-rich 3D modeling, various design disciplines can extract and manipulate relevant tabular or graphical building views such as reports and drawings.

Such an approach can improve building construction and operational performance, increase design efficiencies, and foster an integrated design workflow, among other benefits.

The cost of buildings

Trends in global climate change are correlated with carbon emissions, in that the cost of hydrocarbon fuels upon which world economies are largely dependent is trending upwards, and geopolitical instabilities abound in oil-rich regions of the world.

Reducing our carbon emissions sufficiently to slow global warming will require far more radical changes in energy use than most political and corporate leaders will acknowledge; reversing it in the near term is probably impossible.

At the time of this writing, the catastrophic and anguishing deepsea oil spill in the Gulf of Mexico has once again drawn the world’s attention to the true costs of our society’s dependence on hydrocarbon fuels.

And startlingly, 48 percent of US energy expenditure today is devoted to the building sector—it is roughly evenly divided between commercial and residential structures, including energy costs of materials.

Given the above, there is a real and meaningful environmental impact that building design professionals will have on the state of the world in the coming decades.

Like BIM, sustainable design is also often seen as an approach more appropriate to large projects, again where design fees can absorb the requisite additional research and design innovation.

This perception disregards that residences represent over 20 percent of American energy consumption; our houses, therefore, make a considerable contribution to our societal carbon footprint and the depletion of our energy resources.

Energy efficiency in housing is thus ignored at our peril. Furthermore, large buildings are typically internally load dominated, whereas small projects are envelope or skin-load dominated.

That is climate and how we design for it has a much larger impact on a small building’s energy consumption than it does for a large building’s.

Therefore, having good quantitative data is essential for architects to make more intelligent choices about how they design all projects—even small ones.

See, change

BIM is a design environment that requires that the designer reevaluate the practice of architecture. Distinguishing “design environment” from the “design tool” underscores the reality that BIM represents more than a single tool or software application.

Rather, BIM requires a complete shift in the way one goes about the design process. At the very least, with BIM, buildings are modeled rather than drawn. This may seem very obvious, but the implications are profound.

Modeling represents a radical departure from the way we architects have traditionally undertaken the work of our profession for centuries.

This not only represents a change in the mechanics of our work, but I contend it is a shift in the cognitive processes that accompany and ultimately drive that work. We work differently, and as a result, probably think differently, too.

Furthermore, while modeling decisions may be deferred (a floor, for example, maybe represented as an undifferentiated slab), it is difficult to ignore conditions entirely (“the model doesn’t lie”).

As a result, design decisions are evaluated based on 3D model views as well as from 2D projections of that model.

The former takes the form of perspectives, isometrics, orbital flyovers, fly-throughs, perspective sections, exploded views, and so on.

The latter are “drawing” views that may appear to conform to the graphic conventions of traditional plans, sections, and elevations, but in fact, are just that—views of the ubiquitous model.

Because of the completeness of the virtual building, extracting views (such as elevations and sections) is nearly trivial—generally a matter of a few clicks of the mouse.

As a result, design development and construction documents are produced far more rapidly than in the traditional architectural process of constructed drawings.

This production efficiency has significant effects. As discussed in greater depth in Chapter 1, by necessity more design decisions are taken earlier in the project.

This so-called front-loading (or left-shift in the design phases timeline) of the design process requires that all major geometrical relationships in three dimensions be established earlier. However, the resolution of the details of those relationships may be deferred, as noted above.

The practice of architecture is necessarily affected. Workloads and fee structures must be reevaluated in light of a new paradigm of more time spent in schematic design (SD), and less time spent in the construction documents (CD) phase.

With the possibility to explicitly model structural and mechanical components (and ready-made tools for doing so with relative ease), there are greater opportunities for coordination and collaboration between architects and engineers.

For the architect, an intelligent model helps ensure better coordination of other disciplines. Automatic clash detection—inspecting, analyzing, and alerting the user to undesired interference between model elements—is a BIM feature that originated in automotive and aerospace design software.

Clash detection requires a data-rich model to distinguish colliding supply and return air ducts, for example, from a branching supply duct; or to properly identify a column and beam connection as a desirable “interference” rather than as a “clash.”

Further, common data exchange formats like buildingSMART International’s industry foundation classes (IFC) create opportunities for a more open exchange of models between architect and structural and mechanical engineers.

Conversely, this has given rise to as-yet unresolved issues such as those of model ownership. Nevertheless, BIM and integrated project delivery (IPD) facilitate a more collaborative approach to design that admits structural and mechanical issues as potential design influences rather than mere afterthoughts.

Finally, and the brunt of this book’s objective, BIM creates opportunities for the quantitative assessment of design options. That is, the data bound to the virtual building model can be defined, analyzed, and parameterized by the designer, with the ultimate goal of positively influencing building performance.

As a practicing architect aspiring to produce work of relevance and beauty, I have a vested interest in finding forms that support high-performance buildings and are expressive of that performance.

BIM for the rest of us

For these reasons, I am advocating the somewhat contrarian position that BIM is appropriate as a design environment.

Architectural design is, after all, a process of proposing and evaluating alternative spatial, geometrical, and material solutions to a stated problem of the built environment.

Traditionally qualitative evaluation has been performed in real-time, whereas quantitative analysis is often deferred. BIM, if used as I propose in this book, potentially allows quantitative analysis in real-time.

I must emphasize that in spite of popular perception, BIM methodology—and the shifts it entails—are applicable to projects of all scales. Small-scaled projects are no less prone to erroneous quantitative analysis.

As small buildings are skin-load dominated rather than internally load dominated, their morphology is most impacted by climate.

Indeed, thanks to the greater influence of climate on such buildings, they may benefit all the more from “climate indexing,” whereby building massing, geometry, fenestration, envelope, and interior materials, and passive strategies are specifically tailored to the building’s region and site.

Largely seen as a design and documentation methodology (and ultimately a social convention) rather than a specific technology, BIM promises to allow building designers and stakeholders to leverage greater efficiencies from digital files through the use of such data-rich building models.

Almost universally assumed to be appropriate to large projects with fees to support the “left-shift” in the design process, BIM is often ignored in the context of small projects by many practitioners and software developers.

In most instances the BIM workflow is promulgated for large firms and large projects, the supposition being that small firms and projects can’t sustain the presumed up-front labor costs that BIM implies.

Yet the production benefits that large firms realize from BIM is also translatable to small firms and projects.

Most BIM applications include parametric objects that are suitable for building technologies appropriate to buildings of a variety of scales.

From personal experience I can vouch for that production efficiency that I have consistently realized—even on tiny projects of a few hundred square feet—have paid for more time spent on other aspects of design, or allowed me to deliver projects at lower fees or both.

The “left-shift” that I refer to elsewhere is very much real. According to the Boston Society of Architects, 80 percent of US architecture firms are comprised of six or fewer architects.

Increasing the penetration of BIM and sustainable design practices into small firms will be helpful in counteracting the schism between small-firm and large-firm practice.

As a practicing architect and university lecturer, I have taught building technology, BIM, and design courses. In my experience, BIM in the context of small architectural projects is a much-neglected topic.

I know from personal experience that the assumption that BIM is only appropriate to large projects is false, and that small firms can reap tremendous benefits in sustainable design and production efficiency from a properly integrated BIM work process.

Historically, architects in a variety of firm types all adhered to a similar set of work and documentation conventions; this has been true even to the extent that architects from different regions or countries could understand each other’s documents, variations in building technologies notwithstanding.

Indeed, the profession is practiced universally to the extent that it is quite common for architects to gain their architectural education in one country but develop their early career in another, and, at times, practice in a third.

As both BIM and sustainable design gain, a greater foothold in the architectural community, cultural and technological differences in the practice of architecture in large and small firms may only increase, undermining the universality of architectural training.

Such a schism in the architectural practice is undesirable as it further fractures the profession into increasingly specialized niches.

I further contend that BIM is appropriate for sustainable design. There are currently two general approaches to designing for sustainable projects, each with distinct advantages and drawbacks.

A prescriptive approach, taken by some aspects of Leadership in Energy and Environmental Design (LEED) for example, dictates the measures to be taken to achieve sustainability.

Such prescriptive measures serve as proxies for the actual building and occupant performance. Performance design guidelines, on the other hand, require that an aspect of building operation be modeled as a prediction of actual behavior.

(LEED also has performance guidelines.) The detailed modeling required is well beyond the scope of BIM applications, requiring building energy performance analysis using dedicated energy simulation software.

The BIM model may be exported to the energy modeler, however (See Chapters 1 and 11). Some of the benefits of both prescriptive and performance measures can be attained within BIM, however, through the quantitative analysis techniques that I describe in this book.

The benefit of early analysis— even as early as conceptual design—is that it allows the most influence on building performance with the least effort. BIM’s adaptability is compatible with the performance-driven (sustainable) design.

BIM becomes a sustainable design environment, then, as it potentially integrates quantitative analysis in the design decision-making process.

What BIM In Small-Scale Sustainable Design PDF is, and isn’t

My challenge has been to pen a book that is a useful guide to small- and medium-sized firms that hold a commitment to sustainable design and are contemplating or undertaking the transition to BIM.

As such, I’ve had to walk a fine line between being too general and too specific. A book that is too broad might give an interesting, even thought-provoking, overview of the relationship between BIM, skin-load dominated buildings, and small-design practices.

But without a highly practical perspective on the topic, it might be of little useful relevance to the practitioner and remain a largely academic exercise.

While a theory of BIM is of enormous interest (and essential on some level), it may have little application for most users.

On the other hand, a text that is too detailed, with step-by-step instructions, screenshots, and itemizing particular tasks, might seem attractive, but ultimately would be too limited.

Such a book would be more or less a software manual. While this might suit some BIM users, this approach has several shortcomings.

Aside from many software users’ disinclination to read them, “software manuals” are not relevant to users across a spectrum of proficiencies or at various stages of BIM implementation.

By their very nature, manuals must address a certain level of user with certain skills. Second, manuals naturally must address users of a particular software platform.

While it’s true that Revit, for example, enjoys a large market share, it may not be the software of choice for all users, and there are several other viable alternatives (see Chapter 2).

Third, a software manual is quickly outdated. BIM is a rapidly evolving environment, so even a book that is not tethered to a particular release will need to be updated. But a manual is a reference for one release cycle (about a year), after which it just takes up shelf (or disk) space. Finally, a manual focuses on tasks, not principles.

These tend to be limited to a particular application of the technology, rather than leading to a deeper understanding of the appropriateness of that technology. Fundamentally, then, this book is meant as a guide.

You should be able to read the relevant chapter(s) and then apply the material to actual design projects using the content as a model.

Naturally, this will require that you refer to your software’s documentation for the particular tasks required to implement these strategies.

I have made efforts to be as comprehensive as possible; a scan of the table of contents will reveal a broad range of sustainable design topics.

It will be a rare project indeed that makes use of all aspects of this book. Certain topics will be more or less relevant to a given building given the climate, program, site, and so forth.

The designer using this book should, as always, use professional and practical judgment in determining the applicability of a topic or technique. Don’t expect that in order to design sustainably or design with BIM all aspects addressed here must be applied.

Finally, I should emphasize that in spite of the pervasive discussion of quantitative analysis, the host of other criteria that form the basis of design do not thereby go away.

Your training, experience, aesthetic, and qualitative judgment are all still in play. It is not a matter of either BIM and sustainability or purely architectural design; it is a “both-and” relationship.

You are adding a tool, albeit a powerful one, to your repertoire. Your trusted old tools are not going away, and indeed they must not be neglected.

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