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: Grocery PSC Motors
This memo documents the results of DNV KEMA’s review of the UES (Unit Energy Savings) measure
Grocery PSC Motors. This measure has been categorized by the RTF as Proven, however this memo
recommends that this measure be categorized at Deactivated. This measure category addresses savings
that result from installing a permanent split-capacitance motor (PSC) on a grocery walk-in or display
case evaporator fan in place of a shaded pole (SP) motor. The measure applies to retrofits.
Summary Recommendation. The categorization of this measure should be changed to Deactivated.
The following recommendations lead to a change in category to Deactivated.
1. Whenever this measure is implemented, it is immediately eligible for upgrade through the ECM
motor UES measure. Therefore, it is inappropriate to maintain this measure since it is not the
most efficient measure available for this motor application.
Limitation of Review. None.
Alterations to Workbook and Documentation.

A sheet called “Summary” has been added to the workbook. This worksheet 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.

Since a standardized RTF measure workbook was not available, the standardized workbook
ComGroceryEvapFanPSCMotor_v1_0.xlsm was developed using supporting information from
the RTF workbook DeemedMeasuresV26.xls. Obviously superfluous elements of that workbook
were ignored. All subsequent review was of this new workbook.
o The following worksheets were removed since they did not contain information relating
to the PSC measure
2820 Northup Way, Suite 230
Bellevue, WA 98004
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o
o

 SavingsData&Analysis
 Summary (2)
 ECM on Compressor Fans
 evap fans wi ecm
 evap fans case ecm
Some worksheets contained additional (measure) rows which were not needed for this
particular measure category. These rows were removed, as follows:
 “MeasureTable” worksheet – Row 10
 “Measure_InputOutput” worksheet – Row 10
 “LookupTable” worksheet – Row 5
 “evap fans” worksheet – Rows 4 – 6, 9 – 12, 15 – 16, and 19 (all rows containing
information not specific to PSC motor retrofits i.e. ECM and motor controller
measures ).
The measure description cells on the “LookUpTable” worksheet were filled in with
values sourced from DeemedMeasureV26.xls where applicable.
The calculations for the refrigeration demand savings resulting from the decreased refrigeration
load due to lower Fan Input Power were erroneous. They were calculating a value expressed in
units of MWh (kWh/1000). Cells K4:K9 on the “evap fans ” worksheet were changed to have
their calculations reference the following equation:
𝑅𝑒𝑓𝐷𝑒𝑚𝑎𝑛𝑑𝑆𝑎𝑣𝑖𝑛𝑔𝑠 =
𝑀𝑜𝑡𝑜𝑟𝑆𝑎𝑣𝑖𝑛𝑔𝑠 × 3.413
𝐸𝐸𝑅 × 𝐷𝐹
Where,
RefDemandSavings = “Refrigeration Demand Savings” in kW/motor (Cells K4:K9)
MotorSavings = “Direct Demand Savings” in kW/motor (Cells J4:J9)
3.413 = Conversion ratio of 3.413 kBtu/hour = 1 kW
EER = “EER – Blended” expressed in kBtuh/kW (Cells H4:H9)
DF = Degradation Factor (Cells E4:E9)

The calculations for the indirect energy savings resulting from refrigeration demand savings
previously used the refrigeration system’s compressor full load hours instead of the fan’s run
time hours (Fan Runtime Hours parameter). This was a mistake noted by PECI. The indirect
energy savings due to the decreased load on the refrigeration system should use the runtime
hours of the affected equipment (i.e., the fan motor) that reduced the refrigeration load. Cells
O4:O9 on the “evap fans” worksheet were changed to have their equation reference the Fan
Runtime Hours in Cells D4:D9 instead of the refrigeration system full load hours in Cells F4:F9.

The base case and efficient case Fan Input Power did not match the reference data provided.
The “Efficient Fan Input Watts” values found in Cells C8 and C9 (the “Combined Temp Shaded
Pole to PSC” retrofits) on the “evap fans” spreadsheet were referencing values that were
inconsistent with values used for the low and medium temperature Shaded Pole to PSC retrofit
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values for display cases and walk-ins. Cell C8 (display cases) had the value 29.5, which is the
referenced value for ECM motors in display cases (Cell E50). Cell C9 (walk-ins) had the value
21.0, which is the referenced value for PSC motors in display cases (Cell D45). The values in Cell
C8 and C9 were changed to match the reference data found in Cell D45 and D50. The “Baseline
Fan Input Watts” (Cell B8 and B9 on the “evap fans” worksheet) were also changed to match the
values found in Cell C45 and C50 for their respective case types.

Removed “evap fans” worksheet notes contained in Cell A1. These notes were not applicable to
the PSC motor measure
Recommendations for Updates. The RTF should implement the following recommendations:
1) Workbook Structure and Formulas
a) No changes recommended
2) Documentation
a) No changes recommended
3) Measure Definition
a) This measure is out of date and rarely installed. Also, if it is implemented, it is immediately
eligible for an upgrade to an ECM motor, which is a UES measure that is categorized at
Proven. It is inappropriate to maintain this measure since it is not the most efficient
measure available for this motor application. This deficiency causes a change of category to
Deactivated.
4) UES Savings Estimation Method
a) No changes recommended
5) Input Parameters
a) No changes recommended.
Additional Considerations.
1) None
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