M e m o r a n d u m
FROM:
Jeff Romberger, SBW
TO:
Mark Kendall
DATE:
February 10, 2010
RE:
UES Review and Update Recommendations: Residential Heat Pump Upgrade
CC:
Tom Eckman, Charlie Grist and Adam Hadley
This memo documents the results of PECI’s detailed review of the UES measure category
Residential Heat Pump Upgrade. This measure category covers the incremental savings from
installing an air-source heat pump of above average efficiency, compared to a standard
efficiency heat pump unit, when retrofitting a single family home’s HVAC system or when
building a new single family home. PECI reviewed the RTF measure savings workbook
(Workbook) file Res_SFHeatPumpsFY10v2_3_Reviewed.xls. The review focused on the
derivation of Unit Energy Savings (UES). The current UES values for retrofits were approved by
the RTF on 8/3/2010 and are scheduled to sunset on 8/2/2015. The scope of the UES was
expanded to include new construction projects on 2/14/2012.
Summary Recommendation. This measure category should be re-classified as under review.
The measures should be rerun in the latest version of SEEM (SEEM94) to reflect the latest
information on heating and cooling loads in the region. Additionally, a separate UES category
should developed for new construction applications to account for the difference between an
existing weatherized home and a new home.
Limitation of Review. No attempt was made to verify that the SEEM modeling tool used to
calculate savings was calibrated to measured end-use data. SEEM was used to develop a
number of UES values for residential measures. An independent review of the tool’s
methodology and end-use loads should be undertaken to ensure compliance with the
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Guidelines. It is particularly important to investigate how the tool accounts for system
performance at part load as the actual conditions experienced in each heating zone are likely to
vary from those evaluated when developing the equipment’s HSPF rating.
Additions to RTF Measure Workbook Documentation.


A worksheet called ‘Summary’ has been added to the Workbook. It 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.
The following modifications were made to improve the documentation of sources within
the Workbook:
o Source information was added to the worksheet ‘SEEM Savings’.
Workbook Calculation Errors.

No calculation errors were identified in the review.
Recommendations for Updates. The RTF should pursue the following recommendations for
additional updates:
1) Workbook Structure and Formulas
a) The Workbook currently includes information related to three distinct UES categories:
Residential Heat Pump Conversion, Residential Heat Pump PTCS Controls, Commissioning
and Sizing and Residential Heat Pump Upgrade. While all three categories are relevant
to residential heat pump installations, they represent distinct applications and should be
represented by three stand-alone workbooks to avoid confusion. The following
worksheets should be removed from the Workbook for heat pump upgrades because
they lack relevancy:
 Measure Table – Conversions
 Measure Table – CCS
 HPConvert
 CommissioningControlsSizing
 Duct Sealing Cost
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b) The Worksheet ‘AssumptionsSummary’ should be deleted. The worksheet is redundant
as the measure category is now clearly defined in the new worksheet ‘Summary’.
Additionally, the value for the baseline equipment efficiency is inconsistent with the
values presented in the measure names. Based on the minutes from the RTF meeting
held August 3rd, 2010, it appears a decision was made to change the baseline equipment
heating efficiency from 7.7 HSPF to 8.5 HSPF. The worksheet ‘AssumptionsSummary’
currently displays 7.7 HSPF as the baseline.
c) The Worksheet ‘SEEM Savings’ should be revised to include only those rows relevant to
the upgrade measures (Rows 3, 5, 7).
2) Documentation
a) No additional documentation updates are required at this time.
3) Measure Definition
a) UES unit description is missing from worksheet ‘Lookup Table’, cells F15:F17. Based on
the calculations in ExistingResidentialSingleFamily_SEEMRuns_03.xlsm, it appears the
active unit is per single family home.
4) UES Savings Estimation Method
a) The UES savings were developed in the workbook
‘ExistingResidentialSingleFamily_SEEMRuns_03.xlsm’. An updated version of this
document exists as ‘ExistingResidentialSingleFamily_SEEMRuns_v04.xlsm’. The update
does not appear to have altered the values associated with the upgrade category, but it
makes sense to use the latest version of the file for all measure categories so that
outdated versions can be retired.
5) Input Parameters
a) The measure currently reflects baseline equipment of a heat pump with a rating of 8.5
HSPF. This value was established using Energy Trust of Oregon's 'Air Source Heat Pump
Market Transformation Model Development and Market Research. Prepared by Summit
Blue Consulting, LLC. December 29, 2009' and is intended to represent a typical
installation when incentives are not available. The report indicates that the relative
percentage of units sold with the different heating efficiency levels fluctuated up to 10%
year of year. This input parameter should be reevaluated periodically to ensure the
baseline heat pump heating efficiency level represents a typical installation.
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b) On 2/14/2012, the RTF expanded the scope of this UES category to include new
construction. A separate UES category should be developed for new construction. The
building shell parameters should reflect best practices for the new construction industry
in the region. The baseline heat pump heating efficiency should reflect common practice
for new construction, which may differ from common practice for retrofit applications.
c) As noted in the ‘Limitation of Review’ section of this memorandum, no attempt was
made to verify that the SEEM modeling tool runs used to develop the UES values were
calibrated to metered end-use load data. The Guidelines explicitly state that UES
developed using calibrated engineering must be calibrated to either end-use or whole
building energy usage. The review did find that a newer version of SEEM with updated
infiltration values was approved for use by the RTF on December 13, 2011. This updated
tool could impact the heating and cooling loads used to calculate measure savings. The
measures should be rerun in SEEM94 to reflect the latest information on heating and
cooling loads in the region.
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