PID loops shall be utilized. All chillers, boilers, terminal
changes of properties, setpoint adjustments, alarm/event
units and air-handling units shall have self-contained
information, confirmation of operators, and execution of
BACnet or LONWORKS controllers, capable of
global commands.
communicating with the Building Automation System.
BAS is required for large facilities, both new facilities and
Heating and cooling energy in each zone shall be
gross sq. ft)]. Smaller projects shall be evaluated to
controlled by a thermostat or temperature sensor located
determine the need for a BAS. The size of the building,
in that zone. Independent perimeter systems must have at
number of pieces of equipment, expected energy savings
least one thermostat or temperature sensor for each
and availability of trained staff shall all be considered.
perimeter zone.
A 2.8C (5F) dead band shall be used between
Level of Integration
independent heating and cooling operations within the
same zone.
When planning BAS systems with a high level of
integration, the necessary training will be required
Night set-back and set-up controls must be provided for
for the operating staff.
all comfort conditioned spaces, even if initial building
occupancy plans are for 24-hour operation. Morning
Lighting systems shall not be controlled by a BAS. These
warm-up or cool-down must be part of the control
systems shall have independent control panels and
system. Controls for the various operating conditions
networks. The BAS system shall monitor the status of the
must include maintaining pressurization requirements.
lighting systems only.
Fire alarm systems, security systems and elevator systems
Humidity Controls. Indoor and outdoor humidity
shall not be controlled by a BAS. These systems shall have
sensors shall be calibrated in-place during system startup
independent control panels and networks. The BAS
and at least annually thereafter. Dew point control is
system shall monitor the status of these systems only, in
preferred because it tends to provide more stable
order to prompt emergency operating modes of HVAC
humidity levels. However, RH sensors are acceptable,
and lighting systems. See Chapter 7: Fire Protection & Life
provided they have been calibrated in-place, and provided
Safety, Electrical Requirements, Fire Alarm Systems, and
that they have co-located with dry bulb sensors so that the
Chapter 8: Security Design.
BAS can convert these two signals to a dew point value for
control purposes.
Automatic Temperature and Humidity Controls
Setpoint Reset Controls
A direct digital control (DDC) system with host computer
monitoring and control shall be provided.
Air Systems. Systems supplying heated or cooled air to
multiple zones must include controls that automatically
Temperature Controls. Pre-programmed stand-alone
reset supply air temperature required by building loads or
single or multiple loop microprocessor PID controllers
by outdoor air temperature.
shall be used to control all HVAC and plumbing
subsystems.
155
MECHANICAL
ENGINEERING
5.15
Building Automation Systems (BAS)
Revised March 2005 PBS-P100
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