1003/09 BACnet Standard erweitert

BACnet insight
1. PWR
Using potable (drinking) water
where less-processed water could
be used is a hidden waste of a lot of
energy. A PWR system collects rainwater,
air-conditioning condensation
and/or greywater for uses such as
flushing and irrigation and can earn
from 7 to 14 LEED points.
The BAC can monitor the water
level in the storage tank, switch to
municipal water when the tank is
low, run the pumps when needed,
and monitor water filter usage time.
Extra LEED points can be earned by
recording potable and non-potable
water usage. The BAS alarm system
can also report faults or maintenance
requirements.
2. Lighting
Significant energy savings can be
achieved through automatic lighting
control, and can earn from 1 to
5 points toward LEED certification.
Points can be earned through “daylighting”:
controlling light intensity
in response to the amount of daylight
entering from outside. Points can be
earned using occupancy sensors to
control 75% or more of the lighting.
Points can also be earned by reducing
the power of non-emergency interior
illumination by 50% or more
during the night; the intent is to reduce
“light pollution” but it also
saves energy. Time-limited overrides,
manual or by occupancy sensors, are
permitted.
Most systems specify individual controls
for half or more of building occupants
in individual spaces as well
as for shared spaces. School classrooms
have two “on” modes: general
illumination and audio-visual
mode.
3. Sensors
The use of occupancy sensors and
CO 2 sensors to control BAS operation
can earn from 1 to 8 points,
while also saving energy. The use of
occupancy sensors for lighting has
been noted, but they can also be used
to determine whether HVAC zones
are occupied. CO 2 sensors are specified
for demand-controlled ventilation
in densely-occupied areas or to
monitor naturally-ventilated areas.
4. Measuring and Monitoring
Measuring, monitoring and recording
energy consumption and BAS operation
can earn from 3 to 24 points
while verifying that the building is
operating properly. This includes issuing
alarms when system operation
deviates too far from design. In addition,
LEED encourages having tenants
pay for their measured energy
use.
5. BAS
The final category is the BAS itself,
specified in the LEED standards with
zoning and efficiency or performance
requirements. One point is earned
for having a BAS that controls at
least the HVAC and lighting systems.
LEED points can be earned by controlling
HVAC setbacks by schedule
and occupancy detection. Points
may also be earned by adding diagnostics
for system faults including
leaking AHU valves, 24/7 manual
override, and unusual system
operation.
A BACnet BAS is suited best
Any reasonably capable BAS can
implement the strategies described
above to acquire LEED points. But in
the context of energy-efficient buildings,
BACnet has a unique advantage
over proprietary systems: As an open
standard system, it allows future
strategies to be added when they are
developed.
New methods for reducing a building’s
energy consumption will arise
as BACnet‘s capabilities expand to
support more building systems. To
name just two systems currently in
development by the BACnet committee,
advanced lighting controls
and physical access control; it is not
hard to see the advantages and synergies
that can be gained by combining
these systems.
Responding to increasing energy
demand and limited supply, the
BACnet committee is also developing
standardized communications
between buildings and energy utilities
in order to lower buildings’ energy
consumption during times of peak
demand through demand reduction,
real-time pricing and other strategies.
Once developed, these could be added
to any BACnet building.
With BACnet as the BAS, new capabilities
– which could be developed
by companies that do not yet exist or
with technologies difficult to imagine
today – can be integrated into existing
buildings. Putting BACnet in the
building opens the way to use future
technologies to further “green” the
building.
1 Bill Swan, Honeywell/Alerton USA, ist Vizepräsident der BIG-EU.
bill.swan@honeywell.com
Bill Swan, Honeywell/Alerton USA, is Vice-president of BIG-EU.
bill.swan@honeywell.com
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BACnet Europe Journal 10 03/09
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