Civil Engineering Reference
In-Depth Information
confi gurations systems. It could be easily understood “Day-light System” can
somehow be expressed by PI1 based on the weighted factors of elevation, size,
orientation, location, shading device type and controls, nearby trees, nearby struc-
tures, work-place location and orientation, and internal partition height and fi nishes
in a manner that was explained earlier in this section.
Other than energy consumption per year per square foot of area that is one of the
most important performance indicators in energy modeling, other performance indi-
cators can also be developed to target improving the overall energy effi ciency of the
building and its systems. As we said earlier some aspects of the design cannot be fed
to the current general energy modeling software, for example there is no place for
evaluating the external noise effects on overall energy consumption of the system.
Should we forget this effect, or noise even has any effect at all on the energy con-
sumption of the building. Let's assume we have a building that is designed with a
combination of mechanical and natural ventilation systems. Anytime the outdoor
conditions are favorable system switches to natural ventilation mode, and when the
outdoor conditions are not preferable system switches to mechanical ventilation
mode. Of course natural ventilation mode operation relies on the windows to open
and allow free outdoor air circulation in the building. Existence of external noise, on
the other hand, would limit this favorable mode change and will probably force the
system to run on its mechanical mode more frequently, because people do not desire
to work or live in a building while they are exposed to undesirable high external
noise levels. That of course can be translated to more energy consumption, even
when there are favorable outdoor conditions. This shows that external noise can be
a factor that affects the building energy consumption. The best way to include this
factor in our system design and evaluation therefore is to generate external noise
performance indicators, which needs to be investigated and developed based on the
noise calculation equations, relative distance of the buildings to sources of external
noise, etc. as a benchmark for any other building. This performance indicator in
addition to general energy consumption per year per square foot of the building
should also be met or be exceeded from during the design for a building to be tagged
as energy effi cient building.
As an example of a complete performance-based standard, Qatar sustainability
assessment system (QSAS) is a custom-made sustainability assessment system
designed for the state of Qatar. This system was designed by TC Chan center of
University of Pennsylvania. QSAS is a perfect example of using multiple PIs in
developing a performance-based standard. In this standard for different categories
of design, construction, and operation, different PIs have been calculated and have
been set as the comparison baseline values that any proposed building in the state of
Qatar has to be evaluated against before being constructed. To make a better under-
standing of how such systems work let's look at one of the required performances
and explain how the building has to comply with this requirement.
In order to develop such performance based standard, one needs to develop mul-
tiple PIs to cover the whole required energy aspects of the building by the standard.
For example assume you want to develop the performance indicator for “use of
natural ventilation” in the proposed building. At fi rst you have to calculate the building
