Building automation systems - Intelligent Buildings and Building Automation - page 40

example, supervisory control aims at seeking the minimum energy input
or operating cost to provide satisfactory indoor comfort and a healthy
environment, taking into account the ever-changing indoor and outdoor
conditions as well as the characteristics of HVAC systems. Compared to local
control, supervisory control allows overall consideration of the system-level
characteristics and interactions among all components and their associated
variables.
3.4.3 Risk-management functions
In the same way that a BAS detects temperature and humidity conditions, it
can also be used to detect fire or the presence of smoke. Fire safety integrated
into BAS provides a greater degree of personnel safety than using two inde-
pendent systems. The BAS is able, automatically, to close fire doors, close
some air dampers and open others, start some fans and stop others and pres-
surize some parts of building with respect to others. This can help prevent the
spread of fire and perhaps, more importantly, reduce the spread of smoke.
With the security system incorporated into the BAS, it almost always pro-
vides greater security and therefore reduces risk. Detection of someone trying
to gain unauthorized entry is commonly by sensors on doors and windows.
From the information reported to the central computer, the security officers
can be made aware, not only that an intruder is present or is trying to gain
entry, but also the intruder's location within the building. Access control
differs from security monitoring since as the name suggests it is actually
controlling who has access to a building or certain parts of a building.
3.4.4 Information-processing functions
Performing an economic evaluation of a large BAS is not a trivial assignment,
nor can it be absolutely precise. The basic data needed for the economic eval-
uation is the cost of the BAS and the economic benefits that can be derived
from the BAS. It is likely that the initial cost of the BAS can be estimated
more accurately than the annual savings from energy conservation and other
improvements. Although prediction of dollar savings attributable to energy
conservation features and building management features is difficult, power-
ful systems provide energy monitoring and graph/table reporting, making
estimation easier.
Engineers can directly access actual plant operating conditions through
BAS to monitor energy use and energy cost, to carry out energy audits or to
check performance using computer simulation techniques. With the support
of BAS, a financial report can be produced with much less effort.