Civil Engineering Reference
In-Depth Information
In some standards a mix approach of part performance, part prescription has
been adopted. The more dominated the performance section of a standard or code is
the designer has more freedom in specifying newer products and solutions. For an
involved person in any aspect of the building industry design and construction it is
essential to understand and be capable to execute his duties based on either one of
these methods. Of course we all are fairly familiar with language and structure of
prescriptive codes and standards due to our interaction with such languages through
our daily lives, and there is no need for further explanation here about how these
statements are being written. On the other hand I feel the need for a more compre-
hensive explanation for the performance-based method that just recently has gained
some momentum in the industry code writing environment, even though in other
parts of the world they have been using such standards for a while.
In order to describe the required performances and achievement targets by a
performance-based standard or code the most important steps are to (1) describe
things in a supply and demand language and (2) develop and compare quantifi able
performance indicators (PIs) and key performance indicators (KPIs).
Demand and supply languages are generally referred to the vocabulary that is
being used to describe the required functions and performances of the object or
service intended by the user, and the technical and performance specifi cations rep-
resented by the technical team, respectively. In other word the demand language is
the way that owner or user explains what he needs and supply language is the way
that technical team uses to defi ne and express the performance of the solution pre-
sented to the user or owner to fulfi ll his needs.
The second necessary step in developing a performance-based standard is
developing performance indicators which will act as the representatives of the
effects of the important factors in a process or product.
To simplify understanding of this concept let's assume a group of researchers are
working to generate a performance indicator representing the level of comfort of
occupants in a building. Obviously the fi rst issue that they have to take on is to
specify all the major infl uential factors (systems) on the comfort level of the occu-
pant in the building. The next step then should be to separate the most important
systems from those with negligible or little effects based on the available data from
the existing literatures or through an expert judgment procedure. The following step
then should be to defi ne a mathematical structure for the indicator as a function of
the selected important systems. In our example assume the researchers have selected
environment system and individual system as the two main important systems to
develop a good performance indicator for the building occupants comfort level.
Therefore they decide to describe the comfort performance indicator as follows:
( 5.1 )
The next step is to describe the two main systems based on their important sub-
systems. This once again could be done based on relevant literature review or expert
input and can be described as follows:
PI Occupant comfort level
ƒ
Environment system
,
Human system
Environment system
TH
,
,
AD AV HV
,
,
,
LO
,
( 5.2 )
