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© 2002,
Architectural Energy Corporation.
All Rights Reserved.
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 Funded
by California Energy Commission's Public Interest Energy
Research (PIER) Program
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P2-4. Demonstration of the Whole
Building Diagnostician > Conclusions
Conclusions:
Fault detection and diagnostics for air handlers
can save significant amounts of energy in
medium and large office buildings. The Outdoor Air Economizer module of the
Whole Building Diagnostician
successfully
detected significant
energy wasting faults
in the three demonstration
projects. The
annualized cost of
single faults detected
ranged from $500
to $15,000.
The demonstration reinforced the notion that
diagnostic tools produce savings only when
the identified problems are fixed. Merely identifying operation problems and
their impacts is
not sufficient by itself;
building staff must
fix them. If building
operators are not
able to use their control
systems to correct
problems, are too busy
with other duties,
or lack resources to obtain
help from contractors,
savings will not be
realized. A delivery
mechanism is needed
that helps ensure
that building staff take
action when alerted
to problems with significant
impacts.
The time and cost of diagnostic-tool installation
is a significant component to implementing
diagnostic technologies. Labor costs to set up tools like the WBD
(~1 week) will likely exceed the purchase
cost of commercialized software. Sites with
larger air handlers (10,000 cfm or larger
air flow rates) have greater savings per
problem fixed, while installation costs do
not vary with air handler size (i.e., savings
are greater relative to costs). Installation
costs per air-handler also go down as the
number of air handlers at a site increases,
provided the units use similar operating
control strategies and are part of the same
underlying control system.
Commercialization
potential:
- Battelle is interested in licensing the WBD
software to a commercialization partner.
Contact Carl Imhoff, Product Line Manager,
Energy Products & Operations, Battelle
Memorial Institute, Northwest Division, carl.imhoff@pnl.gov,
voice 509/375-4328.
Recommendations:
- Additional investigation is required into
approaches for delivering the diagnostics
in forms that can be readily used in existing
and future generations of BAS. The project experienced considerable difficulty in getting data automatically
in near-real time from the CSI BAS at the Alameda County facilities as
well as the BACnet compatible BAS at the Capitol Mall building. Data acquisition
from BAS trend logs, however, was not a problem. Motivating building owners
and operators to act on the information from the WBD or other FDD tool
is clearly a major hurdle to actually achieving savings.
Benefits to California:
Based on new data
regarding the characteristics
of California building
stock and statewide
energy use, the projected
benefits of this
project are updated
as follows:
Updated Baseline:
The original baseline conditions and projected
outcome were based on national estimates
because there was no reliable data for California
as a whole. During the course of the Program,
the Commission has established a data set
for California from which the original estimates
can be improved. See Appendix I.
The diagnostics tool demonstrated in Project 2.4 is intended for application
to package HVAC units as well as air handling units in larger commercial
buildings with central plant systems, such as colleges, hospitals, and
large office buildings. The estimated energy consumption for these components
(listed as supply, return, and exhaust fans in Commission's data) is 9328
GWh/yr for Year 2000. The electrical energy used by central plant chillers
to provide cooling water to these devices is estimated to be 4872 GWh/yr.
The total annual electric use is 14,200 GWh/yr.
Updated Outcome:
Colleges, hospitals, and large office buildings are likely to have a large
percentage of built-up air handlers. The total floor area of these facility
types was 1,573 million sf in Year 2000. Assume that AHUs that are controlled
by controllers capable of having embedded diagnostics serve 50% of the
total floor area. Further, assume that if faults are not corrected, they
account for 1 kWh per square foot of floor area of energy use by these
facilities. The total average annual consumption for heating, cooling,
and ventilation for these facilities was about 7.9 kWh/SF in Year 2000.
Thus, faults account for about 13% of electric energy used by these end
uses for these types of facilities. If Project 2.4 diagnostics were used
for 50% of the floor area for colleges, hospitals, and the OAE diagnostics
were 100% effective in timely detection of faults, the total energy savings
would be 786 GWh/yr.
To date, the OAE has found 29 of 30 air handlers on which it has been tested
to have faults, supporting the contention that faults are endemic to outdoor-air
control and economizing. Furthermore, Project 2.7 test results for the
OAE showed that it detected 11 out of 15 faults and that two of the undetected
faults were masked by ambient conditions used for the tests. These two
additional faults would be detected during normal monitoring year round,
indicating that the OAE would likely detect and alert building and service
staff to a large percentage of the faults in air handling equipment.
New and retrofit construction is adding about 380 million sf of commercial space per year. Packaged HVAC units used about 54% of ventilating, cooling, and heating in Year 2000. Assuming this percentage applies to new and retrofit construction, 205 million sf of new conditioned space would be available each year. Assuming that OAE diagnostics are built into control systems for new packaged units, and that the OAE is available on 25% of new units installed, and that the OAE diagnostics were 100% effective in timely detection of faults, the total additional energy savings would be 95 GWh/yr.
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