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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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P1. Rooftop Air Conditioining > Conclusions
Conclusions:
- Applying automated FDD to packaged air conditioning
units will significantly decrease energy
use, improve indoor comfort conditions, and
reduce maintenance costs. The FDD methods investigated in this project
could be applied to cooling equipment that
supplies about 60% of building mechanical
cooling in California. Over 500,000 tons
of air-conditioning are supplied using packaged
units.
- The new FDD method developed for simultaneous
faults is applicable to packaged rooftop
air-conditioners with fixed orifice and thermal
expansion valves. Developing a technique applicable to thermal
expansion valves increases the number of
packaged units that can be served, as well
as opening the possibility for application
to walk-in refrigerated boxes.
- Adoption of FDD for packaged air-conditioners
should be promoted to end users, service
contractors, and HVAC manufacturers. The economic benefits of applying this FDD
system in California ranges between $4000
and $10,000 per packaged unit over a 10-year
life span, which should provide the economic
incentive to use FDD.
Commercialization Potential:
It is envisioned that the FDD methods would
reside in the unit controller and use temperature
measurements to continuously monitor performance
to detect and diagnose faults. Field Diagnostic
Services, Inc., a support contractor on the
research project, is involved in developing
FDD products, and Honeywell, Inc., a match
fund provider on other projects within the
program, participated in the field activities
of this project. Both have expressed interest
in further development of the automated FDD
technology. FDSI is in discussions with other
major controls manufacturers regarding development
of diagnostic services and products from
Project 2.1 research results.
Recommendations:
- Additional research is needed in the areas
of applying the
de-coupling FDD
technique
online in field
testing, improving
the modeling
approach based
on manufacturer's
data, continuing
to improve the
performance model,
expanding
the service cost
database, and consider
other
control diagnostics.
- Recruit commercialization partners to expand
the market. Primarily HVAC unit manufacturers and control
component manufacturers
need to understand
the benefits of
the FDD technology
and why
they should sell
it to their customers.
- Establish incentive programs for mechanical
contractors and building owners to promote
acceptance and use of on-board diagnostics
for rooftop units. This will assist in accelerating availability
of units with FDD
on- board.
- Provide awareness training for building owners,
mechanical contractors, and HVAC trade unions. Testing with field data revealed that many
units have multiple
concurrent faults,
confirming
evidence from other
PIER studies that
maintenance
of rooftop units
is generally lacking.
- Develop automated follow up methods to ensure
equipment functions as intended. The FDD methodology, along with increasingly
sophisticated communications networks within
buildings, should allow continuous or periodic
reviews for equipment faults without visits
to the site.
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:
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 new California
data set established
10
end-use areas, including
three of which may
apply to packaged
rooftop units: cooling,
ventilation, and
heating. The Commission
used a national study
[1] to estimate the
types of cooling
equipment used in
California,
which found that
rooftop units provide
54%
of the cooling end-use
for buildings in
the
United States. Most
rooftop units in
California
use natural gas for
heating, although
there
are some climate
zones in which heat
pumps
are used (estimated
at about 7%, using
data
from [1]). Thus,
the FDD methods investigated
in this project could
be applied to cooling
equipment that supplies
about 60% of building
mechanical cooling
in California. Heat
pumps,
in heating mode,
account for 5% of
energy
used for heating.
Updated Baseline:
The GWh savings estimated
in the original
projected outcome
was based on a baseline
load of 74,677 GWh/yr
for the entire State;
the Commission's
figure for Year 2000
is
91,771 GWh/yr. The
California Commercial
Electricity Consumption
by Building Type
in Year 2000 estimates
that the cooling
end-use
consumed 15.5% of
all electricity used
in
that year, or 14,255
GWh. Fifty-four percent
of this figure, or
7698 GWh, may be
attributed
to DX rooftop units.
The cooling end-use
is the primary target
for the Project 2.1's
technology. Proper
functioning of the
economizer, which
affects
the cooling end-use
and the ventilation
end-use,
is a secondary target.
The state-wide electric
consumption for the
ventilation end-use
is
10% of the total,
or 9,328 GWh/yr.
Assuming
that packaged AC
units account for
54% of
the ventilation energy
used in the state,
packaged air-conditioners
account for additional
5,037 GWh/yr.
The installed cooling
capacity of packaged
air-conditioning
units in California
in Year
2000 is estimated
to be 513,000 tons
(refrigeration).
Survey work sponsored
under another PIER
Program showed that
packaged air conditioners
in the range of 5
to 10 tons (refrigeration
capacity) constitute
about 70% of the
installed
units.
Updated Outcomes:
By 2010 the savings per year would be about 100 GWh for retrofit and new
construction.
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