Environmental Engineering Reference
In-Depth Information
quirements force more applications for intelligent buildings and the con-
trol integration that they utilize.
A distributed control system might control heating and cooling
equipment and other loads such as lighting. Distributed control is applied
at each piece of equipment to provide application specific control.
A number of products have been introduced that use a type of com-
munication network known as sensor or field buses. This technology has
been growing quickly. Remote support can take place through a modem
interface over telephone lines or through the Internet. Building systems
may also do alarm dial outs to pagers and telephones with voice synthe-
sis. Using building wide controllers that support plug-and-play and ob-
jects, the system stores all critical system information at the controller lev-
el. Intelligent controllers of this type make it possible to dial into a system
from a remote location, upload from the controllers and have full access
to the system. Another related building wide control trend is integration
at the functional level. This trend also includes a movement toward inte-
grated control between systems with different functions such as security
and building control systems.
The speed of information transfer can be increased by switching
from twisted pair cables to coaxial or fiber optics, however, these types of
cables add to the installation costs. In the future, communications between
sensors and multiplex boxes and the rest of the system may use a combi-
nation of technologies including traditional means such as twisted wire
and coaxial and non-traditional methods such as infrared or radio wave.
Peer controllers can be used for continuously interrogating the net-
work for sequences such as morning warm-up. This feature would have
been centralized in older systems. A single condition such as outside air
temperature might have been monitored, and the building wide device
would make a decision on start time based on this data and a stored se-
quence. When start up was required, that controller would signal the start
of the sequence. With integrated control of this type, each controller can
make independent decisions based on building wide data as well as lo-
cal controller data. This results in a more reliable and effective building
control system. Equipment level applications that are energy intensive in-
clude air handlers, chillers and boilers. Control sequences include such
expanded applications as start/stop of non-HVAC loads and the on/off
control of lighting and other electrical equipment.
In the future, virtual reality may allow the operator to experience
the environment. Special headsets and gloves may be used. After a com-
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