M e m o r a n d u m
FROM:
Michael Baker, SBW
TO:
RTF Staff
DATE:
February 11, 2013
RE:
Phase I Review and Update Recommendations: Manufactured Home Air Source Heat
Pump Upgrades
This memo documents the results of The Cadmus Group Inc.’s detailed review of the UES (Unit Energy
Savings) measure Manufactured Home Air Source Heat Pump Upgrades. This measure has been
categorized as Proven and therefore this memo outlines recommendations consistent with that
category. This measure covers energy savings from energy-efficient heat pumps installed in
manufactured homes. We also reviewed the SEEM1 workbooks
ExistingResidentialSingleFamily_SEEMRuns_02a.xlsm (and 03a) that relate to the Heat Pump upgrade
measure. The review focused on the derivation of the heat pump upgrade UES values and associated
documentation.
Summary Recommendation. The status of this measure should be changed to Under Review.
The following recommendations lead to a change in status to Under Review.
1. Workbook needs to be updated to use latest ProCost template which includes Measure Cost
and EUL summary sheets.
2. Update the measure to use the results from the most recent version of the SEEM model.
3. Remove requirement that equipment be installed “in substantial compliance with PTCS
specifications.”
4. Define that electric resistance backup heat use is a requirement of this measure.
Limitation of Review
We accept, without review, the climate zones selected to estimate energy consumption of heat pumps.
Climate zones include Portland, Seattle, Spokane, Boise, and Kalispell. We understand savings are
1
The Simple Energy and Enthalpy Model (SEEM) simulation program is designed to model small scale residential
building energy use. http://www.nwcouncil.org/energy/rtf/measures/support/SEEM/Default.asp
2820 Northup Way, Suite 230
Bellevue, WA 98004
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weighted by climate and population and we accept that this strategy reasonably estimates average
energy consumption and savings for heat pump upgrades.
We did not review the details of SEEM models that are used to estimate savings. The input parameters
(worksheets “SEEMinputmap” and “SEEMinput”) and the workbook’s manipulation of the output data
(worksheet “SEEMoutput” and “Results”) were reviewed to check for calculation and consistency errors.
We did not independently run any SEEM models.
Alterations to Workbook and Documentation

Cadmus added a sheet called “Summary” to the workbook. This sheet describes how measures
are identified, lists important constants and their sources. It also describes the savings
estimation algorithm, the associated baseline and efficient case parameters, and their sources
for each measure and UES component.

Cadmus removed the following worksheets:
o
o
o
MeasureTable – CCS
CommissioningControlsSizing
Combined Measures
We removed these worksheets in an effort to house the high efficiency heat pump upgrade
measure in an individual workbook. There are some spreadsheets that contribute to all three of
the heat pump measures (Upgrades; Conversions; and Commissioning, Controls, and Sizing)
which were left in to keep the measure cost portions of the workbook complete.
Recommendations for Updates
The RTF should implement the following recommendations:
1) Workbook Structure and Formulas
a) Workbook needs to be updated to use latest ProCost template, which includes Measure Cost
and EUL summary worksheets. This deficiency causes a change of status to Under Review.
b) Update UES values using most recent SEEM model. The SEEM model referenced in the
workbook is titled: “ExistingResidentialManufacturedHome_SEEMRuns_02.xlsm” (SEEM Version
2a). It appears a newer version exists titled:
“ExistingResidentialManufacturedHome_SEEM94Runs_03a” (SEEM Version 0.94). The newer
version should be used to maintain consistency between similar measures. KEMA recommended
an update1 for a similar measure (Residential: Heating/Cooling - PTCS Commissioning, Controls,
1
See Recommended Memo on RTF website titled: Residential: Heating/Cooling - PTCS Commissioning,
Controls, & Sizing SF
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& Sizing SF) using the latest SEEM (v0.94) modeling. We recommend the same update for this
measure using UES values from SEEM Runs Workbook 3a1. There are differences in all UES
values (see Table 1). This deficiency causes a change of status to Under Review.
Table 1. SEEM Model Output Differences
SEEM Version
3a (kWh)
213
311
149
262
382
184
290
419
204
SEEM Version
2a (kWh)
266
391
184
310
455
214
338
494
236
Measure Description
HeatPump Upgrade - 7.7/13 to 8.5/13 - Heating Zone 1
HeatPump Upgrade - 7.7/13 to 9.0/14 - Heating Zone 1
HeatPump Upgrade - 7.7/13 to 8.2/13 - Heating Zone 1
HeatPump Upgrade - 7.7/13 to 8.5/13 - Heating Zone 2
HeatPump Upgrade - 7.7/13 to 9.0/14 - Heating Zone 2
HeatPump Upgrade - 7.7/13 to 8.2/13 - Heating Zone 2
HeatPump Upgrade - 7.7/13 to 8.5/13 - Heating Zone 3
HeatPump Upgrade - 7.7/13 to 9.0/14 - Heating Zone 3
HeatPump Upgrade - 7.7/13 to 8.2/13 - Heating Zone 3
2) Documentation
a) Add documentation of the study results that have been used to validate and/or calibrate the
SEEM model to manufactured homes. This deficiency causes a change of status to Under
Review.
3) Measure Definition
a) Remove requirement that equipment be installed “in substantial compliance with PTCS
specifications” meaning the measure and savings are based on the equipment only, with no
prescribed installation requirements. There are two related measures that cause this
recommendation:
o This measure: Installation of a heat pump system “in substantial compliance with PTCS
specifications”
o Heat Pump PTCS C,C&S: Installation of a heat pump system by “PTCS Commissioning,
Controls, and Sizing”
The first bulleted item is a requirement of this measure. The second is a different measure that
includes savings in addition to the savings for this measure. According to the RTF measure
workbook for this measure, “Res_MHHeatPumpsFY10v2_4.xls”, the “Heat pump system must be
1
http://www.nwcouncil.org/energy/rtf/measures/support/Default.asp file called:
“ExistingResidentialManufacturedHome_SEEM94Runs_03.xls”
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installed in substantial compliance with PTCS1 specifications.” The measure specification also
states the following exception: “PTCS Commissioning, Controls, and Sizing are not a requirement
of this measure.” Cadmus reviewed all PTCS specifications that are requirements of this heat
pump upgrade measure. It appears that the PTCS Specifications form requires controls and
commissioning in accordance with good, high efficiency installation practice. Cadmus also
reviewed the document “Performance Tested Comfort Systems - Air-Source Heat Pump System
Installation Standards” which is found under the “Program Specifications” section of the Heat
Pump measure reviewed in this memo. If the heat pump upgrade measure had no PTCS
requirements there would be no overlap between the two measures listed above. Although we
recognize the importance of the requirement to use quality installation practices for heat pump
installation, there exists another measure “PTCS Commissioning, Controls and Sizing” to which
savings are attributed. Savings for this heat pump equipment measure should be based on
equipment efficiency differences only. Additional savings are counted if the heat pump is
commissioned. Note that SEEM model runs assume an un-commissioned system, so removing
this requirement is consistent with the model savings. This deficiency causes the measure to
change to status Under Review.
b) Define that existing measures use electric resistance backup heat, as this is the assumption used
to estimate savings. The UES from SEEM models are based on heat pumps with electric
resistance backup heat. If a heat pump system has a backup gas furnace rather than electric
resistance heat, these SEEM runs are not applicable and the UES may be less than expected.2
This deficiency causes the measure to change to status Under Review.
4) UES Savings Estimation Method
a) No recommendations.
5) Input Parameters
a) The primary input parameters for this measure are inputs to the SEEM model. These were
reviewed and no issues were found.
Additional Considerations
1) Add measures for heat pump systems that use non-electric backup heat. During an evaluation of
Avista Utilities service territory in Washington and Idaho we observed a large proportion (~40%) of
1
Performance tested comfort system: www.ptcsnw.com/. The document “Performance Tested Comfort
Systems - Air-Source Heat Pump System Installation Standards” describes installation standards.
2
This depends on the balance point of the heat pump. However, the heat pump may run when the backup
electric resistance heat runs. It will not run if the gas furnace is running. Installing a gas furnace (instead of
electric resistance heat) will always reduce heat pump run time.
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heat pump systems installed backup gas furnaces in single family homes. We expect a smaller
proportion in manufactured homes, but dual-fuel system installations are a possibility that requires
consideration. If a heat pump system has a backup gas furnace rather than electric resistance heat,
the system HSPF is not applicable and the UES may be less than expected1.
2) An alternative to dropping the requirement of “substantial compliance with PTCS specifications” is
to add an eligibility requirement to the Commissioning Controls and Sizing (C,C&S) measure that
participants must not have also claimed savings for this upgrade measure.
1
This depends on the balance point of the heat pump. However, the heat pump may run when the backup
electric resistance heat runs. It will not run if the gas furnace is running. Installing a gas furnace (instead of
electric resistance heat) will always reduce heat pump run time.
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