M e m o r a n d u m
FROM:
Jeff Romberger, SBW
TO:
Mark Kendall
DATE:
March 2, 2012 Version 2, March 15, 2012
RE:
Deemed Measure Detail Review and Update Recommendations: Residential
Manufactured Homes Duct Sealing
CC:
Tom Eckman, Charlie Grist and Adam Hadley
This memo documents the results of EMP2’s detailed review of the deemed measure category
Residential Manufactured Homes Duct Sealing. This measure category covers savings from
improvements made to ducts in existing manufactured homes to reduce air leakage. Duct sealing must
be carried out in accordance with the PTCS (Performance Tested Comfort Standard) duct sealing
specification. EMP2 reviewed the RTF supplied file Res_MHDuctSealingFY10v2_2.xls. We also reviewed
the parts of the SEEM workbook ExistingResidentialManufacturedHomes_SEEMRuns_02.xlsm related to
this measure. The review focused on the derivation of Unit Energy Savings (UES).
Summary Recommendation. This measure category should be re-classified as under review. Additional
documentation for key parameters is needed and the savings runs need to be reanalyzed using SEEM94.
Once these and documentation issues are resolved it can be returned to the active classification.
Limitation of Review. We accepted without review the characteristics of the calibrated SEEM models
and the associated climate and prototype weighting methods. Also, we did not review the macro
“hpmid5bytype” which weights results by heat pump HSPF and control strategy.
Additions to Workbook Documentation.

A sheet called “Summary” has been added to the workbook. This sheet describes how measures
are identified, lists important constants and their sources, describes the savings estimation
algorithm and the associated baseline and efficient case parameters and their sources for each
measure and UES component.
2820 Northup Way, Suite 230
Bellevue, WA 98004
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Workbook Calculation Errors.

An error was found in the SEEM workbook
ExistingResidentialManufacturedHome_SEEMRuns_02.xlsm. On the
“MeasureInputsANDresults” tab, the cooling savings per unit weighted to average house size for
duct tightness (see X213:AB213) uses the “Wx, etc.” weighting (“inputWeightings” tab, B2:B4)
rather than the “Duct Tightness & Insulation” weighting (“inputWeightings” tab, C2:C4). It
should be noted that this error does not affect the savings since the two weighting matrices are
identical.
Recommendations for Updates. The RTF should consider the following findings and recommendations
for additional updates:
1) Workbook Structure and Formulas
a) The workbook should be linked to the latest version of the SEEM runs workbook, which is
currently “ExistingResidentialManufacturedHome_SEEMRuns_03.xlsm”. The workbook does
not currently references SEEM Runs_03.
b) The Measure Table sheet contains the UES values output by the ProCost model. ProCost must
be run after any changes are made to input parameters or UES estimation equations. A quality
control test should be added to this workbook that detects an out-of-date ProCost run by
comparing the input and output UES values.
c) The RTF adopted an updated version of SEEM94 in December of 2011. This updated version
varies the infiltration calculations within the model. The duct sealing measure should be reanalyzed under the most current version of SEEM94 and updated appropriately.
2) Documentation
a) The duct leakage factors used in the SEEM simulations are based primarily on a 2009 Study
(Summary of 2006 NEEM Manufactured Homes) but were modified by Ecotope based on
assumptions. Other studies also informed these assumptions such as the MAP 1995
(Manufactured Home Acquisition Program Analysis of Program Impacts). The main assumptions
are the baseline duct leakage rate estimated at 15% and the post condition duck leakage rate of
5%. The studies appear to support similar figures, but it is unclear of how these percentages
were determined. The 2006 NEEM Study, Table 19: Supply Leakage Fraction has varying results
in terms of Supply Leakage Fraction (SLF), if figures are mainly based on the 2006 NEEM study,
additional data needs to support the baseline and post condition key parameter input. Also, the
NEEM study compares the 2000 sealing standards to the post condition 2006 sealing standards.
A more appropriate study would apply duct leakage values from existing homes prior to
compliance with the current PTCS standard. It is recommended that these assumptions be fully
documented.
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b) As a reference, EMP2 found a document similar to the PTCS Standard. The document is ACCA
Standard 5 (HVAC Quality Installation Specification). This may be a good document to reference
when updating the PTCS Standard.
3) Measure Definition
a) No changes recommended.
4) UES Savings Estimation Method
a) No changes recommended.
5) Input Parameters
a) The baseline and post condition SLF needs further verification and documentation. These
figures are based primarily on the results of the NEEM 2000 and NEEM 2006 Study. The NEEM
study evaluates impacts of changes in specification and manufacturing techniques on the
performance of the homes. A more appropriate study would be a comparison between a large
grouping of existing manufactured homes compared to manufactured homes that are in
compliance with the current PTCS standard. The NEEM study reduced SLF leakage percetnage is
from introducing duct mastic into factories in 2005, not by meeting the requirements in the
current PTCS Standard. It is recommended to further investigate existing studies which may be
more appropriate for this application. EMP2 also found several other documents for
Manufactured Homes that may be beneficial for future reference under the ACEEE website:
1. Comprehensive Evaluation Study of 12,000 California Mobile Homes
2. Measured Heating System Efficiency Retrofits in Eight Manufactured (HUDCode) Homes
3. Savings from an Expedited Duct Sealing Program for Mobile Homes
Overall, EMP2 recommends that the additional documentation and formulation of base and
post condition case key parameters be supported with studies that support existing SLF% to
SLF% that meet the PTCS standard.
Summary of 2006 NEEM Manufactured Homes: Field Data and Billing Analysis, David Baylon et al, Ecotope,
2009.
2
Comprehensive Evaluation Study of 12,000 California Mobile Homes, Anne Blankenship, Robert J. Mowris,
and Ean Jones et al, Robert Mowris & Associates, Dave Robinson and Howard Reichmuth et al, Stellar
Process, 2003.
3
Measured Heating System Efficiency Retrofits in Eight Manufactured (HUD-Code) Homes, Jeff Siegel et al,
Lawrence Berkeley National Laboratory, Berkeley, CA, Bob Davis, Paul Francisco, and Larry Palmiter et al,
Ecotope Inc., Seattle, WA, 1998.
4
Savings from an Expedited Duct Sealing Program for Mobile Homes, Anne Minor et al, West, West and
Company, David Robinson and Howard Reichmuth et al, Stellar Processes, Inc., Tom West et al Eugene
Water and Electric Board, 1998.
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