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From CAD User AEC Magazine Vol 20 No 05 - MAY/JUNE 2007
The term "Building Information Modelling" or BIM was first coined in 2002.
Since then, there has been a gradual but steady uptake. In this article, Dave Shepherd reflects on the main concerns for customers in implementing BIM and why recent developments have spurred an unprecedented level of adoption of this technology
Tradition vs. Transition
Traditionally, design concepts are validated through client meetings and the
development of a brief. Attempts are made to resolve the client's requirements
with several imaginative ideas. These are captured through notes, sketches and
model-making techniques. Once the scheme is designed, it is presented through
a variety of media for approval by the client. It is often only at the stage
of design development that computers are employed for documentation purposes.
There is a consensus among the many early adopters of 2D CAD that the majority
of recent improvements have simply enhanced and extended the technology underlying
its early capabilities. For example, the 2D features present in the early releases
of AutoCAD remain the most popular and frequently used today.
The most powerful use of CAD and IT builds on the ingenuity and methods discovered
by users, rather than the stated purpose of each feature. 1st / 3rd angle projections,
cross sections, elevations and plans are age-old manual drawing techniques invented
long before computers existed. Simple 2D CAD (i.e. lines / arcs / circles) simply
reinforce traditional methods and add very little to a designer's capability.
It's all too easy to focus on improving an existing process rather than evaluating
the benefits of what new tools can provide. As Henry Ford once said "If
I asked my customers what they wanted, they would reply "A faster horse"".
So why is this?
The Price of Change
In business, whatever the potential benefit, we have to choose to change something
in order to do things differently. Economists refer to the expense of change
as "opportunity cost". Innovation incurs an opportunity cost and we
tend to avoid this by resisting new ways of working. Is it any wonder, for instance,
that in spite of the benefits of the metric system, the standard brick width
is 102.5 mm (4 inches)? Or that a door size could be quoted as 1981mm x 838mm?
Sorry, 6'6" x 2'9".
The cost of re-tooling building product factories is just too high. Yes, laugh
if you must, but the distance from King John's nose to his forefinger (the yard)
is still a respected measure.
So, when we consider Building Information Modelling, the primary obstacle to
adoption is the opportunity cost of developing a comprehensive model to replace
the traditional shorthand of drafting. If the metric example is anything to
go by, the likely future will involve a hybrid of both innovative and traditional
methods in order to capture, communicate and review design intent.
BIM: A paradigm driven by new challenges
Building Information Modelling (BIM) describes a variety of predictive techniques
that harness the calculation power of computers. Modelling has been employed
to study financial markets, weather patterns and aerodynamic performance, so
why not apply similar techniques to the field of architectural design?
Many architects think of modelling primarily as 3D visualisation. In their view,
it's simply a scaled artistic rendering of the finished project intended to
impress the prospective client. In actual fact, BIM provides more than visual
data. Cost, performance and design review are all additional by-products of
the simulation effort.
BIM allows you to perform a complete performance simulation of any building.
You can vary the elements and factors that might impinge on that performance.
Materials, ceiling heights, fenestration and roofing can all be changed, measured
and explored before construction takes place. So, BIM is worth considering if
you work on high-value schemes involving substantial amounts of design co-ordination
and revision.
But if that's the case, why is the idea only gaining traction now? One reason
is that only in recent years, software and hardware performance is (finally)
making BIM a viable option. The technology just didn't exist a few years ago
and whilst the concept of modelling a building has been around for a long time,
the systems have been expensive, difficult to use and had limited functionality.
Secondly, there is acceptance in the political and architectural communities
that the issue of waste, both in terms of construction costs and running a building,
must be tackled by improved design techniques.
Finally, it's about exposure to risk. Remember that it was the risk incurred
by complex and fast track construction, rather than the hope of greater profits,
that forced many contractors to apply industrial management techniques such
as PERT and GANNT charts. Nowadays, project management programs are a standard
part of the contractor's software arsenal.
The Challenging Landscape of Modern Design
Today, it is building owners (concerned about running costs and corporate responsibility)
who are driving a demand for better performing buildings - not only in terms
of image and function, but also visual impact and how a building performs technically.
In addition, recent political initiatives to tackle climate change have prompted
efforts to improve sustainability.
All this adds up to a greater need to analyse buildings throughout the design
process and to effect changes more frequently and in less time. Time consuming
2D drafting just does not embrace these new demands and similar to other areas
of business, computer simulation can be used to overcome these challenges.
But what does this mean in practical terms? It means optimising buildings to
reduce consumption and energy use (in fabrication and operation). The use of
locally-sourced renewable materials, improved insulation and energy-optimised
buildings are all part of this effort. It means reducing reliance on fossil
fuel for heating, cooling and lighting by optimising the choice of site, building
orientation and design in order to maximise solar gains and daylight factors.
It means reducing the impact of storm-water discharges on the watershed by reducing
rainfall runoff with green roof and water recycling methods. It means promoting
the clustering of industrial parks, the use of public transportation and car
pooling. With this in mind, designers can achieve better designs through managing
change more effectively.
In summary, BIM is a tool for optimising a buildings performance through simulation,
whilst reducing costly co-ordination errors resulting from this process. The
good news is that the downstream documentation (i.e. drawings and schedules)
are updated throughout this process with considerably less effort than traditional
2D CAD.
The case for BIM is also strong in projects where there are an overwhelming
number of factors to consider and the cost of variations is high. It's no wonder
that the architectural firms who have already adopted BIM are working on complex,
challenging schemes where cost overruns and penalties can spiral into millions.
The cost of implementing BIM is far outweighed by the benefits of improved decision
making and financial control.
BIM allows architects to break out of the drafting paradigm and explore their
design ideas comprehensively, providing a level of validation and analysis that
was just not possible before. With BIM, the simulation can begin at the very
early stages of the validation process, even if many factors are undecided.
We are now starting to see a consensus amongst leading architectural firms that
it's not a question of whether BIM is necessary; it's simply a question of how
to get there.
Dave Shepherd is the UK AEC manager for Cadpoint, an Autodesk Authorised Reseller.
In Part 2 of this article, Dave will explain the practical and technical considerations
when implementing BIM in an architectural environment.
www.cadpoint.co.uk
dshepherd@cadpoint.co.uk
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