Transforming Construction?
4.0 Conventional Design
For the purposes of this discussion, architectural design can be
broken down into two broadly separate areas of activity: actually
doing the design work; and communicating the results of that work to
other individuals or firms involved in the project. Problems arise
when communication requires judgement or interpretation on the part
of the recipient. In this situation there are three main groups of
recipients: the client and his stakeholders; the other members of
the design team; and the construction contractors. Problems of
interpretation using conventional design communications tools and
techniques impact differently on all three of these.
4.0.1 The Client
The client and his team are usually lay people for whom
architectural and technical drawings are more or less
incomprehensible documents, both in terms of the architectural
details they represent, and in terms of the spatial arrangements
they are intended to convey. Architectural illustrations, physical
models of wood and plastic and such like, even the early forms of
computer generated impressions and "walk throughs" are of relatively
little value.
The lay viewer remains unsure, sees something new in every
iteration of the design and reacts with queries, requests for change
and such like. The client's uncertainty introduces delay and
revisions which reverberate throughout the entire design effort. The
efficiency of the design process is undermined and the potential
profitability of all of the participating firms is impaired.
4.0.2 The Design Team
Problems of accurate communication and understanding also arise
in regard to the architect's supporting disciplines. When the design
output takes the form of paper drawings, which have to be inspected
and coordinated by eye at every issue and every revision, these
problems can be particularly severe. Given the cryptic,
discipline-specific language of technical drawings, errors of
understanding are almost unavoidable. Much effort is wasted and
profitability is undermined.
Even when the design firms exchange or share editable CAD files
with each other, problems of interpretation and integration arise.
It is surprisingly common for simple coordination errors to be
overlooked, and such unlikely mistakes as scaling errors, mismatched
origins, misaligned grids and the like occur disturbingly
frequently. These problems impact heavily on the efficiency of the
design process, introducing errors and the need for re-work, again
reducing efficiency and impairing the profitability of the overall
design effort.
4.0.3 The Contractors
The third area where problems of design communications arise is
at the interface with the construction team. There are two main
types of difficulty at this point. First, the inefficiencies and
time lags introduced by the problems outlined above cause disruption
and delay to the design production programme with a variety of
adverse impacts on the subsequent procurement and construction
phases.
The second problem in this area is that, like the blind men and
the elephant, everyone who looks at a set of technical drawings sees
something different. The differences may be slight and easily
reconciled, but frequently even experienced construction people
misinterpret what they think they see. This problem is particularly
acute when multiple orthogonal projections are required to create an
understanding of a complex three dimensional object or space. The
problem is greatly compounded when the thing to be visualised
comprises multi-disciplinary elements.
Delays and disruption in the design delivery programme and errors
in interpretation and understanding of the content of design
documents all lead to drastic inefficiencies in the basic operations
of the industry. More importantly perhaps, they make participants
hesitant, uncertain, and defensive in their dealings with each
other, reluctant to trust and innovate.
4.1 BIM-based Design
These three problems: the typical client's inability to visualise
the design accurately; the difficulty of integrating and
coordinating cross-disciplinary design information; and the limited
ability of constructors to visualise in detail the designer's
intentions all result from the use of drawings - highly stylised,
abstract and cryptic, discipline-specific forms of representation -
to convey the designer's ideas and to guide construction.
The main way in which BIM can help in the building design process
is by dramatically reducing the project team's dependence on
drawings to communicate design ideas. This is not strictly a data
issue so much as a communications ambiguity issue. The key thing
here is the ability to replace lines with components; lines are
ambiguous, components are not.
4.1.1 The Client
When a client views a design he wants to see as clearly as
possible how the designer is proposing to solve his problems. He
wants to see the solution in his terms, or at least in terms that
are clear to him. He wants to see the whole solution; not just how
the building will look, but also how much it will cost and how long
it will take to construct, and the like. And he wants to be
presented with the solution in such a way that he can interrogate it
and interact with it.
Component based BIM models allow exactly this sort of dialogue to
take place. The client can be presented with images that are, in a
sense, better even than photographs of the proposed building would
be. He can immerse himself in the model, walk around it, see views
from outside looking in, from inside looking out. He can see it as
it would look at different times of day at different times of year.
He can see simulations of people moving through the building. He can
swap features like surface finishes at the click of a button. He can
drop a virtual key on a virtual marble floor and hear the sound
reverberate around his virtual foyer.
That deals with how the building will look and feel, even to a
lay viewer. However, one of the crucial features of BIM models is
that they can include a wide range of information types that might
be regarded as being supplementary to the basic design. So in
addition to the building's geometry and such like, a BIM model can
also show the user how much it would cost and how long it would take
to construct the building, depending on which particular
architectural solution he chooses. And this can be done
simultaneously, as he explores the options.
4.1.2 The Design Team
Eliminating visual and architectural ambiguity is a large part of
the appeal of BIM as a means of communication with the client. This
capability is also obviously important in communications between
different members of the design team. However, the power of a BIM
model to act as a means of accurately exchanging precisely
specified, structured data, between the design disciplines is its
most important strength in this context.
Any form of multidisciplinary design is an inherently iterative
process. The lead designer thinks of an idea and draws it up; a
support designer, a structural engineer, for example, considers this
idea and thinks of changes, which he draws up and feeds back to the
lead designer. Lead designer considers the proposed changes, thinks
of changes to them, which he draws up and feeds back to the support
designer. Support designer considers these proposed changes to his
proposed changes and ... And so on. In each of these exchanges, two
possible types of error occur. First, the designers may not
interpret each other's lines or symbols correctly: a line is
construed as representing a pipe rather than a cable, for example;
and secondly, they may transcribe each other's images inaccurately:
line of length 2.003m rather than 2.000m, grid orientation 183.00°,
rather than 184.06°. Obviously these
sorts of issues are compounded enormously as the number of designers
grows and as the complexity of the building increases.
BIM Models overcome these problems in two ways. First, by
presenting the various options in a complete, explicit form, they
reduce the number of iterations needed arrive at the optimum
solution to any given problem. And secondly, by providing a single
data exchange environment, they reduce the potential for error in
each iteration. The result is a streamlined, highly profitable
design process, made even more so by the elimination of low value
drafting activities.
The greatest downstream benefit of the BIM approach in design is
the possibility of consultants being able to deliver fully
coordinated, dimensioned, detailed designs, as the basis for
procurement of specialist trade contractors. The currently prevalent
practice of awarding structural and M&E contracts in particular on
the basis of scheme design or less, is deeply unsound. It is quite
correct to expect contractors, as they have always done, to produce
shop drawings and method statements. But to expect those firms to
produce professional quality coordinated, detailed designs is
unrealistic and potentially deeply contrary to the clients'
interests. BIM techniques, including online access to complete
vendor data from equipment manufacturers, makes it possible for the
consultants to carry out these services properly, professionally and
for them, profitably.
4.1.3 The Contractors
The third audience for whom unambiguous design communication is
important is the construction team. The most obvious benefit a BIM
model offers to contractors is as a visualisation tool, in the
simulation of construction processes. This is particularly valuable
in checking that individual building components don't clash with
each other, either in the course of construction or subsequently,
during maintenance operations. The visualisation capability of BIM
models can also be of great benefit as a means of testing and
demonstrating aspects of the construction itself such as
construction sequencing, logistics, access, storage and security.
However, strategically, by far the most important use of BIM for
construction is in regard to the enormous improvement in the quality
of data it makes available for the purposes of procurement and
management of the construction contracts. These aspects of BIM will
be dealt with in sections 5 and 6.