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Building Automation Systems are mainly used in commercial HVAC
control systems and energy management system applications. Building
Automation itself is an energy management system which saves management
companies and building owners by efficiently controlling air
conditioning and heating comfort systems. BAS is where mechanical and
electrical systems and equipment are joined with microprocessors that
communicate with each other and possibly to a computer. This computer
and controllers in the building automation system can be networked to
the internet or serve as a stand alone system for the local peer to
peer controller network only.
Additionally, the BAS controllers
themselves do not need a computer to operate efficiently as many of
these controllers are designed to operate as stand-alone controllers
and control the specific equipment they are assigned to control. With a
few exceptions, each building automation controller has their own
program and has the ability to communicate to other DDC building
automation controllers. It is important for the building automation
system controllers to communicate to each other.
If the network fails
for whatever reason then the system may still function (because the BAS
controllers in building automation systems are stand-alone) but it will
not function as efficiently as designed. Building Automation Systems
grows more and more complex as time passes but it will save in energy
and maintenance costs if installed and programmed properly. Energy
Management Systems and Building Automation Systems (can be one in the
same) are definitely the way of the future and are replacing older less
efficient systems everyday.
A set-up in a multi-story automated building would have
many
building automation controllers serving different types of air
conditioning and heating equipment (BAS is not limited to just hvac
applications). Every building is different and it is important for the
BAS engineer to select the proper HVAC BAS control system and programs
to control the various types of HVAC systems in a particular automated
building. For building automation systems to be effective, it is
important that the BAS system is installed and tuned properly.
BACnet
- A Data Communication Protocol for
Building Automation and Control Networks
Developed under the auspices of the American Society of Heating,
Refrigerating and Air-Conditioning Engineers (ASHRAE), BACnet is an
American national standard, a European standard, a national standard in
more than 30 countries, and an ISO global standard.
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Some
advantages of a good HVAC BAS building automation system are:
- Building Automation System (BAS) should allow the
owner to set up schedules of operation for the equipment and lighting
systems so that energy savings can be realized when the building or
spaces in the building are unoccupied.
- Building Automation System (BAS) should allow the
equipment optimal start with adaptive learning. Optimal start is
allowing the equipment to be brought on in an ordered and sequential
manner automatically on a schedule before the building is reoccupied so
that space set points can be realized before occupation. Adaptive
learning allows the system to compare space temperature, outside air
conditions, and equipment capabilities so that the equipment can be
turned on at an appropriate time to ensure space set points are
achieved before occupation.
- Building
Automation System (BAS) should have trim and respond capabilities.
Based on zone demand the set point for various heating and cooling
sources will change according to demand from the zones. In a VAV system
all the VAV boxes are served from a central air handling unit. If all
the zones are at set point then the supply air temperature set point of
the air handler is automatically changed to prevent mechanical cooling
from occurring when it is unnecessary. When the zones grow warmer the
supply air temperature set point is automatically lowered to allow
mechanical cooling to satisfy demand. Older systems have a single
supply air temperature set point of 55° Fahrenheit which requires
the compressors to cycle even when it is not necessary.
- Building
Automation System (BAS) should have the ability to monitor energy usage
including the ability to meter electric, gas, water, steam, hot water,
chilled water, and fuel oil services.
- Building
Automation System (BAS) in conjunction with the appropriate mechanical
system set-up should offer economizing based on enthalpy calculations
and/or CO2 set point control.
- Building Automation System (BAS) should have such BAS
control algorithms as reset schedules for heating plants, static
pressure control, and other systems where energy savings can be
realized through these predictive programs.
- Building
Automation System (BAS) should offer load shedding when power companies
are at peak demand and need business and industry to cut back on power
usage to prevent brown outs. Building Automation Systems allow the
owner to cycle various things off like water heaters or drinking
fountains where use of these things will not be noticed even though
they are off.
- Building
Automation System (BAS) should offer the ability to send alarms via
email, pager, or telephone to alert building managers and/or
technicians of developing problems and system failures.
- Management companies who acquire a good building
automation system (BAS) can have BAS set up to bill tenants for energy
usage.
- Building
Automation Systems (BAS) should have the communications abilities to be
integrated with other building automation control systems and TCP/IP.
BACnet compatible or other open source communication protocol is a plus.
DDS (Direct Digital Controls Systems)
Depending on geographical location, a building owner can save lots of
money with a properly designed and calibrated energy management and
control system that will allow the economizer to work through the HVAC
systems direct digital control system. That a good energy management
DDC system has the ability to be monitored from a remote location over
the internet. That it collects trend data and proves energy savings
using charts and graphs not mentioning the fact that the final proof
will be the lower utility bill. That devices that are out of
calibration or broken can be observed from the remote location and
action taken to repair such devices. A good DDC energy managment system
will do all this and more.
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