20030228Response to Comments.pdf

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MONICA MOEN ISB #5734
Idaho Power Company
O. Box 70
Boise, Idaho 83707
Telephone No. [phone]
FAX Telephone No. [phone]
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Attorney for Idaho Power Company
Street Address for Express Mail
1221 West Idaho Street
Boise , Idaho 83702
BEFORE THE IDAHO PUBLIC UTILITIES COMMISSION
IN THE MATTER OF THE
APPLICATION OF IDAHO POWER
COMPANY FOR AUTHORITY TO
IMPLEMENT A RESIDENTIAL AIR
CONDITIONER CYCLING PILOT
PROGRAM.
IDAHO POWER COMPANY'S
RESPONSE TO COMMENTS
CASE NO. IPC-02-
COMES NOW, Idaho Power Company ("Idaho Power" or "the Company
by and through its attorney of record, and, in response to the comments of the
Commission Staff and the NW Energy Coalition , Idaho Rivers United and Advocates for
the West (collectively referred to as the "NW Energy Coalition ), hereby submits the
following reply comments.
COMMENTS OF THE COMMISSION STAFF
AND
NW ENERGY COALITION
The Company will address the comments made by Staff and the NW
Energy Coalition in reference to the Residential Air Conditioner Cycling Pilot Program
and Tariff Schedule 81.
IDAHO POWER COMPANY'S RESPONSE TO COMMENTS , Page
Meterinq
Throughout Staff's comments , the Staff identifies the meters that the
Company proposes to use for the AC Cycling Pilot Program (lithe Program ) as time-of-
use (TOU) meters. TOU meters record kilowatt-hour data in time blocks that are
preprogrammed into the meter. Instead , the Company proposes to use a mass
memory meter capable of recording and storing interval load data and monthly kilowatt
hour data for billing purposes.
Proposed Cvclinq Options
The Staff recommends that Idaho Power implement and evaluate all of the
AC cycling options listed in the tariff. The three cycling routines proposed in the tariff
are:
Cycle the Central Air Conditioning compressor for a specified length of
time on a percentage basis.
Cycle the Central Air Conditioning compressor until a specified
temperature change is attained.
Change the temperature set point on the thermostat for a specified
length of time.
If all the cycling routines are not tested, Staff prefers that the temperature
set point method be implemented in the pilot.
The Company shares the Staff's concerns about participants ' comfort and
satisfaction. At the same time , Idaho Power believes that it can learn from the
IDAHO POWER COMPANY'S RESPONSE TO COMMENTS , Page 2
experience of other utilities and the advice of the vendors of load control systems who
describe these recommendations and experiences. The Company should not be limited
to exploring strategies that have been shown to be less optimal elsewhere or to ignore
new system capabilities that have the potential to increase load reduction and/or
improve participant comfort. The Company has defined AC cycling broadly in the tariff
in order to maintain flexibility in this pilot to enable the Company to test different
routines.
Idaho Power has recently selected a vendor to provide thermostats and
provide support for this Program. Representatives of this vendor recommend that
because of Idaho s hot dry climate , the routine that is likely to be the most successful for
Idaho Power would be a fifty percent cycling routine, that is, cycling for a specified
length of time on a percentage basis. This routine would turn off a customer s AC
compressor fifteen minutes out of every thirty minutes during a cycling event.
The thermostat purveyors and other utilities report that the temperature
set point routine is a less effective cycling routine for reducing peak load over a set
period of hours. Under this cycling routine, the load is immediately reduced as it is in
the other routines, but electrical load reduction gradually decreases as the cycling event
progresses. Idaho Power does not discount this option given the need to balance
customer comfort and load reduction. As Idaho Power stated to Staff in response to an
email dated February 18, 2003, lithe flexibility to try different strategies may improve our
chances for success in establishing the feasibility of an AC cycling program." Idaho
Power, with input from the Energy Efficiency Advisory Group ("EEAG"), has attempted
IDAHO POWER COMPANY'S RESPONSE TO COMMENTS, Page 3
to design, and hopes to test , a pilot program that will achieve maximum load reduction
at the minimum cost with the highest customer satisfaction.
Effects on AC compressor life
In reference to the Air Conditioning & Refrigeration Institute (ARI)
Guideline For Energy Management Systems and Load Management Through Duty
Cycling (Attachment A), Staff states liThe Company dismisses this concern." The
Company does not dismiss this concern. Instead , the Company draws different
conclusions from this report and other evidence the Company has gathered concerning
premature wear on AC compressors than does Staff.
The Staff states "Idaho Power dismisses the reported detrimental effect
because DOE's purpose was to report the effect of over-sizing rather than utility
controlled cycling." The Company did not dismiss the DOE report entitled, Energy-
Efficient Air Conditioning (Attachment B). The Company pointed out that the emphasis
of this report was on the sizing of AC units. The report does not address load control
cycling. In fact, this report affirms that if a customer s AC compressor is oversized , it
will 'over cycle' whether the customer is a participant in this Pilot Program or not. Thus
load control cycling will not be detrimental, but over sizing would be. An oversized air
conditioner cycles more often for many days on end while load control cycling occurs
infrequently and for limited time periods.
If a fifty percent cycling routine is used, the AC compressor will turn off
only twice per hour. This operation is well within the industry guidelines. (See
Guideline Number 4, cycle rate, in Attachment A.) A properly sized air conditioner
IDAHO POWER COMPANY'S RESPONSE TO COMMENTS , Page 4
would likely operate continuously during extreme heat and , thus, exhibit no cycling. The
same air conditioner would cycle a number of times per hour during less than, extreme
periods. Frequent cycling during moderate temperatures is normal and should not
decrease the life of the air conditioner. The proposed Program is designed to prevent
short cycling" in which the compressor is commanded to come on prior to a reasonable
cooling down period after it was last shut off.
Staff suggests that Idaho Power provide each Program participant with a
copy the DOE Energy Efficient Air Conditioning report and ARI Guideline A. Idaho
Power believes that by providing participants with these reports, Idaho Power would be
implying that the Company has concerns with the proposed program when , in fact , it
has no such concerns. Idaho Power would not choose to implement this Program if the
Company believed the Program could cause damage to a customer s air conditioner
compressor. Other utilities operating air conditioner cycling programs in the United
States report that damage to air conditioning units has not been a problem despite the
fact that these programs have been in operation for over 20 years.
In their comments, Staff states "Staff believes the option of adjusting the
thermostat's temperature set-point will not have this effect because it will not cause
compressors to cycle more frequently." The Company disagrees. At a fifty percent
cycle, a customer s AC compressor, if running, will be turned off twice an hour, once
every fifteen minutes. Under this percentage cycling routine, the Company would be
cycling AC compressors within normal industry standards. By changing the
temperature set point, the Company has no idea how many cycling events would occur.
IDAHO POWER COMPANY'S RESPONSE TO COMMENTS , Page 5
The number of cycling events may be more or less than the unit would normally cycle.
This would only add uncertainty to the Program.
Evaluate Effects of Proqrammable Thermostats
In its comments , Staff recommends evaluating the effects of the advanced
programmable thermostats. The primary goal of this pilot program is to reduce summer
peak loads by cycling residential customers' AC compressors. The cycling will provide
an immediate dispatchable load reduction. Through analysis of data stored in the mass
memory meters and data stored in the thermostats, the Company will be able to
aggregate the information and estimate the peak demand reduction by participants in
this Program due to the AC cycling. Evaluating the effects of programmable
thermostats on either energy consumption or average demand is not within the scope of
this pilot. When the Company stated that these thermostats "may reduce overall energy
use" it was identifying a possible secondary potential benefit of the Program. Some of
the energy savings participants may obtain from these sophisticated thermostats may
be attributed to potential reduced heating costs in the winter months in the form of
reduced use of fuels other than electricity which the Company has no ability or desire to
monitor.
Importance of Reportinq
The Company agrees with Staff that information gathering is the primary
goal of a pilot program. However, the Company believes that the information gathered
analyzed and reported in a pilot program should be directed at the viability of the pilot
IDAHO POWER COMPANY'S RESPONSE TO COMMENTS , Page 6
program s objectives and scope. Idaho Power, with input from the EEAG , has designed
a pilot program to test the feasibility of deploying a residential air conditioner cycling
program. The pilot program analysis has been designed to target the issues that are
significant, measurable and reportable. Adding participants , testing more and different
Demand Side Management programs, or enlarging the scope of this pilot could delay
the deployment of this Program and the analysis of the data collected and ultimately not
satisfy the test of feasibility for an ongoing AC cycling program. The Company believes
that the additional analyses and reporting recommended by Staff are not related to the
goal of the Program , will not be beneficial to its overall evaluation and will likely delay
the Program.
In its comments , Staff notes "it has still not received a full report for the
Company s 1999 Idaho City automated meter reading trial." The 1999 Idaho City
automated meter reading (AMR) trial was intended to test Two-Way Automated
Communication System (TW ACS) power line technology to see if it would work on
Idaho Power s system. The Company did not make a filing with the Idaho Public
Utilities Commission for this trial nor did the Company have any reporting obligation on
the Idaho City AMR trial. Nevertheless , Idaho Power informed the Staff of this program.
On March 30 , 1998 , Idaho Power personnel met with Stephanie Miller and other
Commission Staff and made a presentation concerning the Idaho City AMR trial. On
April 18 , 1998, several Commission Staff members including Beverly Barker, Randy
Lobb and Rick Sterling visited Idaho Power s headquarters to receive an overview of the
AMR trial , to see the two types of meters used and to watch a demonstration of how
information inputs and outputs were conducted. They received information regarding
IDAHO POWER COMPANY'S RESPONSE TO COMMENTS , Page 7
outage detection , outage magnitude, restoration and reliability reporting by AMR. At
this demonstration , Staff members operated the AMR system to access actual meter
information. Idaho Power believes that it has acted in good faith and has been
forthcoming in all matters related to the 1999 Idaho City AMR trial.
Control Groups
In addition to the participant group, Staff proposes evaluating multiple
control groups. The attached spreadsheets (Attachment C) illustrate the expected
levels of precision that might be achieved under ideal conditions comparing a non-
cycling control group as recommended by Staff with the participant group. Assuming at
the end of the first year there are 200 participants and 200 non-participants in a control
group, the margin of error in a comparison of the groups' loads for an hour would be
roughly plus or minus 39%. Assuming later in the program there are 500 participants
and 500 customers in a control group, the margin of error would drop to plus or minus
24%. The differences in load reductions between control groups may well be within the
margin of error. Given the relatively large margin of error in these estimates, it is
unlikely that the additional cost of control groups would yield results of significance and
value.
Control groups , however, would add significant costs to the project. The
budgeted installed costs for mass memory meters to store interval data is approximately
$39 000 the first year and an additional $58 000 the second year. (See Attachment D).
Similar metering costs for control groups can be avoided by using participants' data
from non-cycling days, which is the methodology recommended by the Company, in lieu
IDAHO POWER COMPANY'S RESPONSE TO COMMENTS , Page 8
of a control group. This approach would still have a significant margin of error in the
estimated load reduction but the costs would be much lower. If the control group were
selected from the volunteers for the Program, the total number of actual Program
participants could be diluted. If the Program costs were to be held to the budgeted
amount, the actual number of Program participants would be decreased by a factor of
two or three depending upon the number of control groups utilized.
To increase the accuracy of the load reduction estimates, the Company is
exploring the option of using smaller intervals than the 15-minute intervals that are often
used in load studies. If load data were collected in 5-minute intervals, then there would
be intervals where the air conditioner compressors were completely on or completely off
in addition to transition intervals. This increased resolution might enable improved
engineering estimates of the load reduction from cycling. However, the feasibility of
collecting 5-minute interval data has not yet been established and would certainly
increase the costs of the pilot program.
Staff suggests the use a control group with mass memory meters and
without Company-supplied programmable thermostats and without the knowledge that
they are part of a control group for the pilot program. People who volunteer for the
Program may have different behaviors and attributes than customers who qualify but do
not volunteer. This issue is known as "self-selection bias." If a control group were
selected from a group that is different from the participant group, its loads may not be
an accurate representation of what the participants' loads would have been if a cycling
event did not occur.
IDAHO POWER COMPANY'S RESPONSE TO COMMENTS , Page 9
Another concern in establishing this control group is that the Company
records do not include information concerning which customers have central air
conditioners or which customers do not have programmable thermostats. Selecting a
control group without active cooperation from customers would not be impossible but it
would be difficult , expensive and delay deployment of the Program.
Other Demand Side Manaqement ProQrams addressinq Air ConditioninQ
Idaho Power, with input from the EEAG , has designed a pilot program to
test the feasibility of deploying a dispatchable residential air conditioner cycling
program. This Program is designed to address reduction of summer peak demand on
Idaho Power s system. The Company s plan is to operate the Program such that the
peak load is reduced in a uniform and dispatchable manner. For the Company to
measure and evaluate the sizing of AC units , adequate return air flow of residential
HV AC systems , proper charging of residential AC equipment , the cleanliness of coils on
residential AC equipment , properly sealed ducts in residential HV AC systems
household insulation and sealed building envelopes of residences, as well as
promotion of evaporative coolers instead of residential air conditioners is out of the
scope of this pilot program. Programs similar to these have been and are being
considered by the Company in consultation with the EEAG , but will require separate
program design , evaluation and goals.
IDAHO POWER COMPANY'S RESPONSE TO COMMENTS , Page 10
Customer Incentives and Promotional Costs
Both the Staff and NW Energy Coalition support increasing the customer
incentive. When the Company first presented the residential AC Cycling Pilot Program
to the EEAG, the Program contained no financial incentive for the participating
customers. Other utilities with similar programs use the free programmable thermostat
as the only incentive to participate. Austin Energy, for example , offers only the installed
free programmable thermostat as a customer incentive and has 24 000 participants.
The members of the EEAG felt strongly that the participants must receive
a monetary incentive as well as the installed thermostat. The Company and EEAG both
felt that the incentive could be increased in the future but it would be difficult, if not
impossible, to decrease the incentive and maintain participation in the future. The
Company believes, and the EEAG has concurred , that $5 is an appropriate level to
begin the incentive. If the Company finds that it is difficult to enlist participants at this
incentive level , the incentive could be increased at a later date.
Expanded Proqram
The NW Energy Coalition noted in their comments that the Company
DSM Rider funds are not fully allocated and , thus , an expanded program should fall
within the Company s DSM budget. The Company believes that the monies allocated
for the AC cycling program are adequate to test a pilot program. The Company has
approached the expenditure of rider funds as a need for a portfolio of programs directed
at the different customer classes. The Company has a number of programs in the
IDAHO POWER COMPANY'S RESPONSE TO COMMENTS , Page
planning stage and any resources not yet allocated will be used to investigate other
DSM options.
CONCLUSIONS
Both the Staff and the NW Energy Coalition have recommended
increasing the incentives to customers. The NW Energy Coalition also recommended
increasing the size of the Pilot Program. The Company believes that increasing the
Program size , incentives, or scope of this pilot program and/or adding multiple control
groups would add significant costs to the Program with little or no statistical or analytical
benefits. Changing the scope and intentions of this Program could cause delays in its
implementation or delays in the research necessary to assess if an ongoing program is
effective, practical and economical.
DATED at Boise , Idaho, this 28th day of February, 2003.
MONICA MOEN
Attorney for Idaho Power Company
IDAHO POWER COMPANY'S RESPONSE TO COMMENTS , Page 12
CERTIFICATE OF SERVICE
I HEREBY CERTIFY that on the 28th day of February, 2003, I served a
true and correct copy of the within and foregoing IDAHO POWER COMPANY'
RESPONSE TO COMMENTS upon the following named parties by the method
indicated below, and addressed to the following:
Lisa Nordstrom
Deputy Attorney General
Idaho Public Utilities Commission
472 W. Washington Street
O. Box 83720
Boise, Idaho 83720-0074
Hand Delivered
S. Mail
Overnight Mail
FAX
William M. Eddie
Advocates For the West
O. Box 1612
Boise, Idaho 83701
Hand Delivered
S. Mail
Overnight Mail
FAX
MONICA MOEN
CERTIFICATE OF SERVICE
ATTACHMENT A
. -
1987
GUIDELINE for
(REAFFIRMED 1997)
iii
.,.
AIR-CONDITIONING &
REFRIGERATION
INSTITUTE
ENERGY
MANAGEMENT
SYSTEMS AND
LOAD
MANAGEMENT
THROUGH
DUTY
CYCLING
Guideline
4301 NORTH FAIRFAX DRIVE ARLINGTON. VIRGINIA 22203
IMPORTANT
SAFETY RECOMMENDA nONS
It is strongly recommended that the product be designed, constructed, assembled and installed in accordance
with nationally recognized safety requirements appropriate for products covered by this guideline.
ARl, as a manufacturers' trade association, uses its best efforts to develop guidelines employing state-of-the-
art and accepted industry practices. However, ARI does not certify or guarantee safety of any products
components or systems designed, tested, rated, installed or operated in accordance with these guidelines or
that any tests conducted under its standards will be non-hazardous or free from risk.
Note:
This is a new guideline.
(Reaffinned 1997)
Price $5.00 (M) $10.00 (NM)
Printed in U,
ftDi;
~.,.
(oCopyright 1987, by Air-Conditioning and Refrigeration Institute
Re!!istered United States Patent and Trademark Office
ARI GUIDELINE A-1987
ARI GENERAL GUIDELINES ON ENERGY MANAGEMENT
SYSTEMS AND LOAD MANAGEMENT THROUGH DUTY
CYCLING
ARI recognizes the desire of many customers, users and
other building owners to install some sort of energy
management system (EMS) device on heating, ventilating,
air conditioning and refrigeration equipment. It is also
recognized that some power suppliers feel the need to effect
load management through duty cycling," a program
designed to reduce the peak load on a power distribution
system and hence delay or eliminate the need for additional
generating capacity. ARl offers these guidelines without
stipulating that either energy savings, user comfort or
equipment perfonnance will be achieved.
The product scope of ARI encompasses a wide variety of
products. The availability of various type of EMS devices is
very broad and the effect of such devices on equipment
warranties may vary product-by-product and manufacturer-
to-manufacturer. Therefore, ARl urges that the equipment
manufacturer be contacted for specific recommendations
concerning that equipment.
The general guidelines are as follows:
Safety
Do not alter, disable or bypass any of the safety
controls.
Control Circuits
Control the unit operation through the control
wiring. An auxiliary power supply may be required
to carry the load of any additional field supplied
controls. Additional load on the equipment
transfonner can cause voltage drop, chattering
contactors, and ultimate failure of motor-
compressor or other components.
3. Fail-Safe Requirement
In the event of failure of an add-on control
device( s), the nonnal operation of the equipment
being controlled should not be jeopardized.
4. Cycle Rate
Do not short cycle motor controllers, motors, or
motor-compressors. The compressor off cycle must
be five (5) minutes or longer. If more than four (4)
cycles per hour are anticipated, contact the
equipment manufacturer for specific
recommendations.
5. Fossil Fuel Heating Equipment
Do not short cycle or underfire fossil fuel heating
equipment. Adequate burner operating time and
temperature is necessary to prevent condensation
damage to heat exchanger and/or flue.
In the event of any conflict between the manufacturers
specific instructions and these Guidelines, such instructions
should prevail over these Guidelines.
The infonnation in these Guidelines is current as of the date
of publication. These Guidelines are only guidelines and
should not be referred to or construed as a standard
certification or warranty. The appropriate steps to be taken
with respect to duty cycling devices should be done by and
under the supervision of qualified and experienced personnel
to insure proper installation, and should be properly
inspected. However, no changes in these Guidelines (when
identified as ARl guidelines) shall be made without the
approval of ARl.
Released for publication by the ARI General Standards
Committee on June 12, 1985.
Note: Published in the approved ARI Guideline Fonnat in
1987 without change.
ATTACHMENT B
ENERGY
EFFICIENCY
AND
RENEWABLE
DOE/GO-1O099-379
FS 206
June 1999Energy-Efficient
Air Con di ti 0 ning
Are you considering buying a new air
conditioner? Or. are you dissatisfied with
the operation of your current air condi-
tioner? Are you unsure whether to fix or
replace it? Are you concerned about high
summer utility bills? If you answered yes
to any of these questions. this publication
can help, With it, you can learn about
various types of air conditioning systems
and how to maintain your air conditioner,
hire professional air conditioning services
select a new air conditioner, and ensure
that your new air conditioner is properly
installed.
Understanding Air Conditioners
Many people buy or use air conditioners
without understanding their designs,
components, and operating principles.
Proper sizing, selection, installation
maintenance. and correct use are keys to
cost-effective operation and lower overall
costs.
This publication discusses both central
and room air conditioners. Heat pumps.
which provide both home cooling and
heating, are not covered in this publica-
tion, Contact the Energy Efficiency and
Renewable Energy Clearinghouse
(EREC-see Source List below) for more
information about heat pumps of all kinds.
How Air Conditioners Work
Air conditioners employ the same operat-
ing principles and basic components as
your home refrigerator. An air conditioner
cools your home with a cold indoor coil
called the evaporator. The condenser, a hot
outdoor coil, releases the collected heat
outside. The evaporator and condenser
coils are serpentine tubing surrounded by
aluminum fins. This tubing is usually
made of copper. A pump, called the
compressor, moves a heat transfer fluid
(or refrigerant) between the evaporator
and the condenser. The pump forces the
The fluid that collects heat at the evaporator and releases it at the condenser is called refrigerant.
A pump. called the compressor. forces the refrigerant through the circuit of tubing and fins inthe coils. Air moves through the tiny spaces between the fins and is cooled by the refrigerant in
the coils.
This document was produced for the US Department of Energy (DOE) hy the National Renewable Energy Laboratory (NREL), DOE national laboratory,
The document was produced by the InformatIon Services Program, under the DOE Office of Energy Efficiency and Renewable Energy, The Energy Efficiency
and Renewable Energy Clearinghouse (EREC) is operated by NCI Information Systems, Inc" for NREL/ DOE The statements contained herein are based on
information known to EREC and NREL at the time of printing No recommendation or endorsement of any pmdua or service is implied if mentioned by EREe
Printed with a renewable-source ink on paper containing at least 50% wastepaper, including 20% postconsumer waste
refrigerant through the circuit of tubing
and fins in the coils. The liquid refrigerant
evaporates in the indoor evaporator coil
pulling heat out of indoor air and thereby
cooling the home. The hot refrigerant gas
is pumped outdoors into the condenser
where it reverts back to a liquid giving up
its heat to the air flowing over the
condenser s metal tubing and fins.
Types of Air Conditioners
The basic types of air conditioners are
room air conditioners, split-system central
air conditioners, and packaged central air
conditioners.
Room Air Conditioners
Room air conditioners cool rooms rather
than the entire home. If they provide cool-
ing only where they re needed, room air
conditioners are less expensive to operate
than central units. even though their
efficiency is generally lower than that of
central air conditioners.
Smaller room air conditioners (Le., those
drawing less than 7.5 amps of electricity)
can be plugged into any 15- or 20-amp,
lIS-volt household circuit that is not
shared with any other major appliances.
Larger room air conditioners (Le., those
drawing more than 7.5 amps) need their
own dedicated lIS-volt circuit The
largest models require a dedicated
230-volt circuit.
Condenser fan
Evaporator fan
Room Air Conditioner
Room air conditioners are installed directly in windows or walls, which means
they have no ductwork. The evaporator s fan faces indoors, while the condenser
fan faces outdoors.
Central Air Conditioners
Central air conditioners circulate cool air
through a system of supply and return
ducts. Supply ducts and registers (Le.
openings in the walls, floors, or ceilings
covered by grills) carry cooled air from the
air conditioner to the home. This cooled
air becomes warmer as it circulates
through the home; then it flows back
to the central air conditioner through
return ducts and registers. A central air
conditioner is either a split -system unit or
a packaged unit
In a split-system central air conditioner
an outdoor metal cabinet contains the
condenser and compressor, and an indoor
cabinet contains the evaporator. In many
split -system air conditioners, this indoor
cabinet also contains a furnace or the
indoor part of a heat pump. The air
conditioner s evaporator coil is installed
in the cabinet or main supply duct of this
furnace or heat pump, If your home
already has a furnace but no air
conditioner, a split-system is the most
economical central air conditioner to install.
In a packaged central air conditioner, the
evaporator, condenser, and compressor
are all located in one cabinet, which
usually is placed on a roof or on a concrete
slab next to the house s foundation. This
type of air conditioner also is used in
small commercial buildings. Air supply
and return ducts come from indoors
through the home s exterior wall or roof to
connect with the packaged air conditioner
which is usually located outdoors. Pack-
aged air conditioners often include electric
heating coils or a natural gas furnace. This
combination of air conditioner and central
heater eliminates the need for a separate
furnace indoors.
Maintaining Existing
Air Conditioners
Older air conditioners may still be able to
offer years of relatively efficient use.
However, making your older air condi-
tioner last requires you to perform proper
operation and maintenance,
Packaged Air Conditioner
Evaporator
Condenser
A packaged air conditioner sits outside the house next to the foundation or on the
roof. Its cabinet contains the evaporator. condenser. compressor, and all other parts
ofthe air conditioner. Supply and return ducts connect to this outdoor cabinet.
Evaporative Coolers
An evaporative cooler (also called a "swamp cooler ) is a completely different
type of air conditioner that works well in hot, dry climates.
Evaporative Cooler
i'h
::z
Evaporative coolers cost about half as much as central air conditioners and
use about 25% less energy.
These units cool outdoor air by evaporation and blow it inside the building,
causing a cooling effect much like the process when evaporating perspiration
cools your body on a hot (but not overly humid) day. When operating an
evaporative cooler, windows are opened part way to allow warm indoor air
to escape as it is replaced by cooled air.
Evaporative coolers cost about one-half as much to install as central air condi-
tioners and use about one-quarter as much energy, However, they require
more frequent maintenance than refrigerated air conditioners and they're
suitable only for areas with low humidity.
Air Conditioning Problems
One of the most common air conditioning
problems is improper operation. If your air
conditioner is on, be sure to close your
home s windows and outside doors.
Other common problems with existing air
conditioners result from faulty installation
poor service procedures, and inadequate
maintenance. Improper installation of your
air conditioner can result in leaky ducts
and low air flow. Many times, the refriger-
ant charge (the amount of refrigerant in the
system) does not match the manufacturer
specifications. If proper refrigerant charging
is not performed during installation, the
performance and efficiency of the unit is
impaired. Service technicians often fail to
find refrigerant charging problems or even
worsen existing problems by adding refrig-
erant to a system that is already full. Air
conditioner manufacturers generally make
rugged , high quality products. If your air
conditioner fails, it is usually for one of the
common reasons listed below:
refrigerant leaks. If your air conditioner
is low on refrigerant, either it was
undercharged at installation, or it leaks,
If it leaks , simply adding refrigerant is
not a solution. A trained technician
should fix any leak. test the repair, and
then charge the system with the correct
amount of refrigerant. Remember that
the performance and efficiency of your
air conditioner is greatest when the
refrigerant charge exactly matches the
manufacturer s specification, and is
neither undercharged nor overcharged,
inadequate maintenance. If you allow
filters and air conditioning coils to
become dirty. the air conditioner will
not work properly, and the compressor
or fans are likely to fail prematurely,
electric control failure. The compressor
and fan controls can wear out, especially
when the air conditioner turns on and
off frequently, as is common when a
system is oversized, Because corrosion
of wire and terminals is also a problem
in many systems, electrical connections
and contacts should be checked during
a professional service call.
The most important
maintenance task
that will ensure the
efficiency of your air
conditioner is
routinely replace
clean its filters.
Regular Maintenance
An air conditioner s filters, coils, and fins
require regular maintenance for the unit to
function effectively and efficiently
throughout its years of service. Neglecting
necessary maintenance ensures a steady
decline in air conditioning performance
while energy use steadily increases.
Air Conditioner Filters
The most important maintenance task that
will ensure the efficiency of your air con-
ditioner is to routinely replace or clean its
filters, Clogged , dirty filters block normal
air flow and reduce a system s efficiency
significantly. With nonnal air flow obstructed
air that bypasses the filter may carry dirt
directly into the evaporator coil and
impair the coil's heat-absorbing capacity.
Filters are located somewhere along the
return duct s length. Common filter
locations are in walls, ceilings, furnaces, or
in the air conditioner itself.
Some types of filters are reusable; others
must be replaced. They are available in a
variety of types and efficiencies. Clean or
replace your air conditioning system s filter
or filters every month or two during the
cooling season. Filters may need more
frequent attention ifthe air conditioner is
in constant use, is subjected to dusty
conditions, or you have fur-bearing pets
in the house,
Air Conditioner Coils
The air conditioner s evaporator coil and
condenser coil collect dirt over their
months and years of service. A clean filter
prevents the evaporator coil from soiling
quickly. In time, however, the evaporator
coil will still collect dirt. This dirt reduces
air flow and insulates the coil which
Leakage at registers
reduces its ability to absorb heat.
Therefore, your evaporator coil should be
checked every year and cleaned as
necessary.
Outdoor condenser coils can also become
very dirty if the outdoor environment is
dusty or if there is foliage nearby. You can
easily see the condenser coil and notice if
dirt is collecting on its fins.
You should minimize dirt and debris near
the condenser unit. Your dryer vents.
falling leaves, and lawn mower are all
potential sources of dirt and debris.
Cleaning the area around the coil, removing
any debris, and trimming foliage back at
least 2 feet (0.6 meters) allow for adequate
air flow around the condenser.
Coil Fins
The aluminum fins on evaporator and
condenser coils are easily bent and can
block air flow through the coil. Air
conditioning wholesalers sell a tool called
a "fin comb" that will comb these fins
back into nearly original condition.
Sealing and Insulating Air Ducts
An enormous waste of energy occurs
when cooled air escapes from supply
ducts or when hot attic air leaks into
return ducts. Recent studies indicate that
10% to 30% of the conditioned air in an
average central air conditioning system
escapes from the ducts.
For central air conditioning to be efficient
ducts must be airtight. Hiring a competent
professional service technician to detect
and correct duct leaks is a good investment
since leaky ducts may be difficult to find
without experience and test equipment.
Duct Leakage at Seams and Registers
Air from hot attics can leak into the home around registers of the duct system. Air in the ducts
can leak out through holes and seams.
Ducts must be sealed with duct "mastic.
The old standby of duct tape is ineffective
for sealing ducts.
Obstructions can impair the efficiency of a
duct system almost as much as leaks. You
should be careful not to obstruct the flow
of air from supply or return registers with
furniture , drapes, or tightly fitted interior
doors. Dirty filters and clogged evaporator
coils can also be major obstructions to air
flow.
The large temperature difference between
attics and ducts makes heat conduction
through ducts almost as big a problem as
air leakage and obstructions, Ducts in
attics should be insulated heavily in
addition to being made airtight,
Using Your Air Conditioner
An air conditioner will cool the air in your home fairly quickly. For economical
operation, turn it on only when your home is occupied. You may consider
installing a programmable thermostat. These allow you to set the time when
the air conditioner will turn on, such as 30 minutes before you arrive home
from work on a hot day. Contact EREC (see Source List) for the fact sheet
Automatic and Programmable Thermostats. During the day, keep the drapes or
blinds closed on windows that face east, south, and west. This will help reduce
solar heat gain into your home.
Buying New Air Conditioners
Today's best air conditioners use 30% to 50%
less energy to produce the same amount
of cooling as air conditioners made in the
mid 1970s. Even if your air conditioner is
only 10 years old, you may save 20% to 40%
of your cooling energy costs by replacing
it with a newer. more efficient modeL
Sizing Air Conditioners
Air conditioners are rated by the number
of British Thermal Units (Btu) of heat they
can remove per hour. Another common
rating term for air conditioning size is the
ton " which is 12 000 Btu per hour.
How big should your air conditioner be?
The size of an air conditioner depends on:
. how large your home is and how many
windows it has;
. how much shade is on your home
windows, walls, and roof;
. how much insulation is in your home
ceiling and walls;
. how much air leaks into your home
from the outside; and
. how much heat the occupants and
appliances in your home generate.
An air conditioner s efficiency. performance.
durability, and initial cost depend on
matching its size to the above factors.
Make sure you buy the correct size of air
conditioner. Two groups-the Air Condi-
tioning Contractors of America (ACCA)
and the American Society of Heating,
Refrigerating, and Air Conditioning
Engineers (ASHRAE)-publish calculation
procedures for sizing central air condition-
ers. Reputable air conditioning contractors
will use one of these procedures. often
performed with the aid of a computer, to
size your new central air conditioner.
Be aware that a large air conditioner will
not provide the best cooling, Buying an
oversized air conditioner penalizes you in
the following ways.
. It costs more to buy a larger air
conditioner than you need.
. The larger-than-necessary air condi-
tioner cycles on and off more frequently,
reducing its efficiency. Frequent cycling
makes indoor temperatures fluctuate
more and results in a less comfortable
environment. Frequent cycling also
inhibits moisture removaL In humid
climates, removing moisture is essential
for acceptable comfort. In addition, this
cycling wears out the compressor and
electrical parts more rapidly.
. A larger air conditioner uses more
electricity and creates added demands
on electrical generation and delivery
systems.
Air Conditioner Efficiency
Each air conditioner has an energy-
efficiency rating that lists how many Btu
per hour are removed for each watt of
power it draws. For room air conditioners
this efficiency rating is the Energy
Efficiency Ratio, or EER. For central air
conditioners, it is the Seasonal Energy
Efficiency Ratio, or SEER. These ratings
are posted on an Energy Guide Label
which must be conspicuously attached to
all new air conditioners. Many air condi-
tioner manufacturers are participants in
The higher
initial cost of an
energy-efficient
model will be repaid
to you several times
during its life span.
the voluntary EnergyStarCID labeling
program (see Source List in this publication).
EnergyStar-labeled appliances mean that
they have high EER and SEER ratings.
In general, new air conditioners with
higher EERs or SEERs sport higher price
tags, However, the higher initial cost of an
energy-efficient model will be repaid to
you several times during its life span.
Your utility company may encourage the
purchase of a more efficient air conditioner
by rebating some or all of the price
difference. Buy the most efficient air
conditioner you can afford, especially if
you use (or think you will use) an air
conditioner frequently and/or if your
electricity rates are high.
Room Air Conditioners-EER
Room air conditioners generally range
from 5 500 Btu per hour to 14 000 Btu per
hour. National appliance standards
require room air conditioners built after
January 1 1990, to have an EER of8.0 or
greater. Select a room air conditioner with
an EER of at least 9.0 if you live in a mild
climate. If you live in a hot climate, select
one with an EER over 10.
The Association of Home Appliance
Manufacturers reports that the average
EER of room air conditioners rose 47%
from 1972 to 1991. If you own a 1970s-
vintage room air conditioner with an
EER of 5 and you replace it with a new
one with an EER of 10. you will cut your
air conditioning energy costs in half.
Central Air Conditioners-SEER
National minimum standards for central
air conditioners require a SEER of 9.7 and
10., for single-package and split-systems
respectively. But you do not need to settle
for the minimum standard-there is a wide
selection of units with SEERs reaching
nearly 17.
Before 1979, the SEERs of central air con-
ditioners ranged from 4.5 to 8.0, Replacing
a 1970s-era central air conditioner with
a SEER of 6 with a new unit having a
SEER of 12 will cut your air conditioning
costs in half.
Hiring Professional Service
When your air conditioner needs more
than the regular maintenance described
previously, hire a professional service
technician. A well-trained technician will
find and fix problems in your air condi-
tioning system. However, not all service
technicians are competent. Incompetent
service technicians forsake proper
diagnosis and perform only minimal stop-
gap measures. Insist that the technician:
. check for correct amount of refrigerant;
. test for refrigerant leaks using a leak
detector;
. capture any refrigerant that must be
evacuated from the system. instead of
illegally releasing it to the atmosphere;
. check for and seal duct leakage in
central systems;
. measure air flow through the evaporator
coil;
. verify the correct electric control
sequence and make sure that the heating
system and cooling system cannot
operate simultaneously;
. inspect electric terminals, clean and
tighten connections, and apply a non-
conductive coating if necessary;
. oil motors and check belts for tightness
and wear; and
. check the accuracy of the thermostat.
Choosing a Contractor
Choosing a contractor may be the most
important and difficult task in buying a
new central air conditioning system. Ask
prospective contractors for recent references,
If you are replacing your central air
conditioner, tell your contractor what you
liked and did not like about the old
system. If the system failed, ask the
contractor to find out why. The best time
to fix existing problems is when a new
system is being installed.
When designing your new air conditioning
system, the contractor you choose should:
. use a computer program or written
calculation procedure to size the air
conditioner;
. provide a written contract listing the
main points of your installation that
includes the results of the cooling load
calculation;
. give you a written warranty on equip-
ment and workmanship; and
. allow you to hold the final payment
until you are satisfied with the new
system.
Avoid making your decision solely on
the basis of price. The quality of the
installation should be your highest
priority. because quality will determine
energy cost, comfort, and durability,
Installation and Location of
Air Conditioners
If your air conditioner is installed
correctly, or if major installation problems
are found and fixed, it will perform
efficiently for years with only minor
routine maintenance. However, many
air conditioners are not installed correctly,
As an unfortunate result, modern energy-
efficient air conditioners can perform
almost as poorly as older inefficient models.
Be sure that your contractor performs the
following procedures when installing a
new central air conditioning system:
. allows adequate indoor space for the
installation, maintenance, and repair of
the new system, and installs an access
door in the furnace or duct to provide a
way to clean the evaporator coiL
. uses a duct-sizing methodology such as
the Air Conditioning Contractors of
America (ACCA) Manual
. ensures there are enough supply
registers to deliver cool air and enough
return air registers to carry warm house
air back to the air conditioner.
. installs duct work within the conditioned
space. not in the attic, wherever possible.
. seals all ducts with duct mastic and
heavily insulates attic ducts,
. locates the condensing unit where its
noise will not keep you or your
neighbors awake at night, if possible.
. places the condensing unit in a shady
spot, if possible. which can reduce your
air conditioning costs by 1 % to 2%.
. verifies that the newly installed air
conditioner has the exact refrigerant
charge and air flow rate specified by the
manufacturer,
. locates the thermostat away from heat
sources, such as windows, or supply
registers.
All ducts should be insulated when they are
located in attics or crawl spaces.
Sealing Ducts
Reputable contractors seal alljoints in both
new and existing ducts with duct mastic.
If you are replacing an older or failed split
system, be sure that the evaporator coil is
replaced with a new one that exactly
matches the condenser coil in the new
condensing unit. (The air conditioner
efficiency will likely not improve if the
existing evaporator coil is left in place;
in fact, the old coil could cause the new
compressor to fail prematurely,)
If you install a new room air conditioner
try to:
. locate the air conditioner in a window
or wall area near the center of the room
and on the shadiest side of the house.
. minimize air leakage by fitting the room
air conditioner snugly into its opening
and sealing gaps with a foam weather
stripping material.
Paying attention to your air conditioning
system saves you money and reduces
environmental pollution. Notice whether
your existing system is running properly.
and maintain it regularly. Or, if you need
to purchase a new air conditioner, be sure
it is sized and installed correctly and has a
good EER or SEER rating.
1J,
::;:::;:
ATTACHMENT C
Idaho Power Company
Control Group Statistics
Air Conditioner Cycling Pilot Program
2/27/2003
rou = 200
Size of control group (n(c))
Size of participant group (n(p))
200
200
oe:==input
oe:==input
Standard deviation of population (s)
Standard error of difference of means (se)
351
235
in kW (from load research)
computed
Confidence level
Normal deviate (z)
90%
645
oe:==input
computed
Margin of error (+/- d)387 inkW
Difference of means (m(c)-m(p))
38.
assuming 1 kW avg AC load reduction from
cycling 50% of ACs having 2 kW loads,
ercent of mean difference
Partici
Size of control group (n(c))
Size of participant group (n(p))
500
500
oe:==input
oe:==input
Standard deviation of population (s)
Standard error of difference of means (se)
351
149
in kW (from load research)
computed
Confidence level
Normal deviate (z)
90%
645
oe:==input
computed
Margin of error (+/- d)245 inkW
Difference of means (m(c)-m(p))
24.
assuming 1 WII avg AC load reduction from
cycling 50% of ACs having 2 WIIloads,
ercent of mean difference
74 The formula for the relative margin of error (r) is this:75 r=z* sA2 * 1/n
Formulas for Control Group Statistics
Size of control group (n(c)) 200 oe:==input
Size of participant group (n(p)) 200 oe:==input
Standard deviation of population (s)
Standard error of difference of means (se)
351
((662A2)*(1/659+1/660))AO,
in kW (from load research)
computed
Confidence level
Normal deviate (z)
90%
NORMSINV((1 +665)/2)
oe:==input
computed
Margin of error (+/- d)663*666 in WII
Difference of means (m(c)-m(p))
Relative margin of error (+/- r)668/670
assuming 1 WII avg AC load reduction from
cycling 50% of ACs having 2 kW loads,
percent of mean difference
Case No, IPC-O2-
2/28/2003
ATTACHMENT D
Idaho Power Company
Estimated Costs
Air Conditioner Cycling Pilot Program
Year
2 Number of Participants
3 Thermostat CosUUnit
4 Installation CosUUnit
Thermostat Cost (2 x (3 + 4))
6 Palm Pilots (Thermostat Data Recorders)
7 System Implementation & Training
8 System Hosting
9 Software Fees
10 Communications Costs11 Control System Cost (Sum 6 : 10)
12 Interval Meters CosUMeter
13 Interval Meter Installation CosUMeter14 Metering Cost (2 x (12 + 13)
15 ManagemenUData Analysis/Evaluation/Recruitment
16 Promotion
17 Ongoing Maintenance
18 Customer Incentives19 General Programs Costs (Sum 15: 18)20 Total Cost per Year (5 + 11 + 14 +19)21 Total Cost for two Years (208 + 20C)
Idaho Power Company
Case No, IPC-O2-
2003
200
$195
$50
$49 000
380
$19,000
000
250
300
$33 930
$187
$38,716
$115 000
$100 000
$50 000
000
$268,000
$389 646
2004
300
$195
$50
$73,500
000
700
800
$16 500
$187
$58,074
$115 000
$100 000
$50 000
500
$272 500
$420 574
$810 220