Sustainable Construction A Life Cycle Approach in Engineering

3.5 Configurations
Within the matrix many combinations can be made between a structure group, a building layer
and an indicator. These combinations will be named configurations (figure 4). When pipes of a
water distribution system are poured into the concrete of a floor, the configuration of these
pipes with the floors probably has a low score on the indicator of integration, since the pipes
are unreachable when maintenance is necessary. When in an office building a workspace is
created with only columns as structural elements in the floor-plan, the obstruction of the space
usage between the vertical elements will yield a good score.
Not every configuration in the matrix is possible. Besides many configuration have limited
relevance. Space usage is a non-physical building layer and will not be able to technically
integrate with the structure. Also the non load-bearing walls cannot undergo obstruction of the
structure since they are elements spaced in between the structure.
Figure 4: The 3D-matrix contains many cells with little pieces of information.
Some of these configurations are crossed out due to its limited relevance.
4 SURVEY
To determine the scores on a global level a number of configurations have to be aggregated,
bringing new problems along. As mentioned before different indicators are important to
different building layers, meaning in every direction many different weighing factors are
needed to obtain the global scores. Finding objective criteria for the weighing factors proves to
be very difficult and often depends on the subjectivity of the observer. Personal perception and
the context of the time have a large influence on the question of what is important.
Interdependencies between the indicators form a second problem. When a configuration is
completely integrated, the connection and accessibility of this configuration will not score high
either.
For the latter problem Hoekman (2009) already introduced the use of Fuzzy Logic (Zadeh,
1965), a theory that enables one to quantify grammatical problems into values that can be
aggregated by a rule box. Complicated relations like the ones that occur in the matrix can be
tied down.
This study simplifies the demand for weighing factors in all directions. As a step towards these
weighing factors a survey was held among experts to determine the key configurations in the
matrix. The expert panel existed of 16 researchers, structural engineers and undergraduate
students, experienced within the subject. This panel was asked in a survey to estimate the
importance of the different parameters. Though the population of the panel was fairly small, the
correlation in answers was high. The survey results show a peak of importance around some
groups of configurations (figure 5), but on the other hand the difference between the other
configurations was too little to draw conclusions.
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