M e m o r a n d u m
FROM:
TO:
DATE:
RE:
This memo documents the results of DNV KEMA’s review of the UES (Unit Energy Savings) measure
Grocery Walk-In Evaporator Fan ECM Controllers. This measure has been categorized by the RTF as
Proven, and therefore this memo outlines recommendations consistent with that category. This measure addresses savings that result from installing a fan speed controller (controls full speed and low speed operation) on a grocery walk-in case evaporator fan with an electronically commutated motor
(ECM) motor. The measure applies to retrofits. The review focuses on the derivation of Unit Energy
Savings (UES).
Summary Recommendation. The status of this measure should be changed to Out of Compliance.
The following recommendations lead to a change in status to Out of Compliance.
1.
Collect and implement primary or a sufficiently reliable secondary data source to establish the
Full Speed Fan Motor Input Power for the 16 to 23 watt motor size category
2.
Collect and implement primary or a sufficiently reliable secondary data source to establish the
Low Speed Fan Motor Input Power.
3.
The Average EER parameter needs to be derived transparently from publically available regional data.
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.
Document basis for the baseline Annual Fan Operating Hours. If documentation is not available, use the recommended source for low temperature (LT) units and an expert panel to develop documented values for medium temperature (MT) units.
2820 Northup Way, Suite 230
Bellevue, WA 98004
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Limitation of Review. None
Alterations to Workbook and Documentation.
 Revised the “Application” criteria (Column M on the “LookupTable” worksheet) with the following: o “Must control a minimum fan load of 1/20 hp per fan, operating continuously at full speed. Must reduce fan motor power by at least 75% when operating at reduced speed.
Not recommended if any of the following conditions exist: 1) the compressor runs with a very high duty cycle (more than 65%); 2) the evaporator fan does not run at full speed all the time; or 3) the evaporator does not use off-cycle or time-off defrost. This measure cannot be used in conjunction with Efficient Evaporator Fan Motor measure.”
 The calculations for the Motor Energy Savings UES component have been modified to directly reference post retrofit high-speed and low-speed fan operating hours. The previous method referenced available Percent Runtime figures, but not operating hours directly. This caused uncertainty as to what actual operation hours are used. o Additional columns were added in the WI ECM Cycling (2-speed) worksheet to indicate calculated Full Speed and Low Speed fan operating hours. Equations for Proposed Evap
Fan motor energy usage (Cells U35:U38) were changed to have their calculations reference the following equation:
𝑃𝑟𝑜𝑝𝑜𝑠𝑒𝑑 𝐴𝑛𝑛𝑢𝑎𝑙 𝐸𝑛𝑒𝑟𝑔𝑦 =
[(𝐻𝑖 𝑆𝑝𝑒𝑒𝑑 𝑂𝑝𝑒𝑟𝑎𝑡𝑖𝑛𝑔 𝐻𝑜𝑢𝑟𝑠) × (
𝐼𝑛𝑝𝑢𝑡 𝑃𝑜𝑤𝑒𝑟 − 𝐻𝑖𝑔ℎ 𝑆𝑝𝑒𝑒𝑑 (𝑊)
1000
)]
+ [(𝐿𝑜𝑤 𝑆𝑝𝑒𝑒𝑑 𝑂𝑝𝑒𝑟𝑎𝑡𝑖𝑛𝑔 𝐻𝑜𝑢𝑟𝑠) × (
𝐼𝑛𝑝𝑢𝑡 𝑃𝑜𝑤𝑒𝑟 − 𝐿𝑜𝑤 𝑆𝑝𝑒𝑒𝑑(𝑊)
1000
)]
Where,
Hi Speed Operating Hours (Cells N35:N38) = 𝐴𝑛𝑛𝑢𝑎𝑙 𝐻𝑜𝑢𝑟𝑠 (8,760) ×
𝐵𝑎𝑠𝑒 𝐹𝑢𝑙𝑙 𝑆𝑝𝑒𝑒𝑑 𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑅𝑢𝑛𝑡𝑖𝑚𝑒 (𝐶𝑒𝑙𝑙𝑠 𝐺35: 𝐺38) ×
𝑃𝑟𝑜𝑝𝑜𝑠𝑒𝑑 𝐹𝑢𝑙𝑙 𝑆𝑝𝑒𝑒𝑑 𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑅𝑢𝑛𝑡𝑖𝑚𝑒 (𝐶𝑒𝑙𝑙𝑠 𝐿35: 𝐿38)
Low Speed Operating Hours (Cells R35:R38) = 𝐴𝑛𝑛𝑢𝑎𝑙 𝐻𝑜𝑢𝑟𝑠 (8,760) ×
𝐵𝑎𝑠𝑒 𝐹𝑢𝑙𝑙 𝑆𝑝𝑒𝑒𝑑 𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑅𝑢𝑛𝑡𝑖𝑚𝑒 (𝐶𝑒𝑙𝑙𝑠 𝐺35: 𝐺38) × (1 −
𝑃𝑟𝑜𝑝𝑜𝑠𝑒𝑑 𝐹𝑢𝑙𝑙 𝑆𝑝𝑒𝑒𝑑 𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑅𝑢𝑛𝑡𝑖𝑚𝑒 (𝐶𝑒𝑙𝑙𝑠 𝐿35: 𝐿38) o As a result of making these revisions, a discrepancy was found in the savings calculations. The calculation for the Proposed Evap Fan Motor Annual kWh, found in
Cells P35:P38 of the WI ECM Cycling (2-speed) worksheet, references Proposed Evap Fan
Motor Avg Input (Cells O35:O38) and Annual Hours (Cells D35:D38). Proposed Evap Fan
Motor Avg Input then references the Proposed Full Speed Percent Runtime (Cells
K35:K38), but doesn’t appear to reference the Baseline Full Speed Percent Runtime
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(Cells G35:G38), which accounts for decreased operation of LT evaporator fan motors due to defrost. This discrepancy was addressed in the revisions. A summary of the changes that the revisions had on the savings are presented in the following table.
Motor Description
1/10-1/20 Hp (37.3-74.6 W)
16-23 Watt
Refrig.
Temp
MT/LT
LT
LT
WI ECM Cycling
(2-Speed) Savings
Pre Revision
WI ECM Cycling (2-
Speed) Savings Post
Revision kW kWh kW
0.0257 206.6 0.0269
0.0101 81 0.0105 kWh
230.1
90.2
Difference kW
-0.0012
-0.0005 kWh
-23.5
-9.2 o References found in the “Savings Summary” worksheet were changed to reference the revised calculations in the WI ECM Cycling (2-speed) worksheet. This includes Cells
E13:H16 and J13:K16 on the “Savings Summary” worksheet.
Recommendations for Updates. The RTF should implement the following recommendations:
1) Workbook Structure and Formulas a) Update workbook with latest ProCost template to include Measure Cost and Effective
Useful Life (EUL) summary sheets. This deficiency causes a change of status to Under
Review
2) Documentation a) No changes recommended
3) Measure Definition a) No changes recommended
4) UES Savings Estimation Method a) No changes recommended
5) Input Parameters a) Recommend collecting primary meter data or use a sufficiently reliable secondary data source to establish the Full Speed Fan Motor Input Power for the 16 to 23 watt motor size category. Currently, the 16 to 23 watt motor size category references a ratio developed from a primary data source that forms the average Full Speed Fan Motor Input Power for the 1/10 to 1/20 hp motor size category. This recommendation is also relevant for the
Grocery Walk-In Evaporator Fan Shaded-Pole Controllers, Grocery Walk-In ECMs, and
Grocery PSC Motors measures, where the data sources for those measures are either unreliable or need to have explicit documentation in order to be considered Active status.
This deficiency causes a change of status to Out of Compliance.
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b) Recommend collecting primary meter data or use a sufficiently reliable secondary data source to establish the Low Speed Fan Motor Input Power. The Low Speed Fan Motor Input
Power uses the Full Speed Fan Motor Input Power and an analyst-assumed Fan Law
Exponent value of 2.5. The use of this assumed exponent is not in-line with the Guidelines for meta-statistical UES estimation procedures. This recommendation is also relevant for the Grocery Walk-In Evaporator Fan Shaded-Pole Controllers measure, which uses the same assumption for the Fan Law Exponent. The procurement of primary data or a sufficiently reliable secondary data source would subsume the Fan Law Exponent and the Fan Speed.
This deficiency causes a change of status to Out of Compliance. c) The Average EER parameter is based on proprietary DOE 2.2-R simulations of Northwest grocery environments. The Degradation Factor will need to be removed as a parameter from the UES Savings Estimation Method and spreadsheet calculations and incorporated into the Average EER value to include this degradation impact. This parameter needs to be derived transparently from publically available data. This deficiency causes a change of status to Out-of-Compliance. d) Further documentation support is needed for the baseline Annual Fan Operating Hours. No source is currently cited for this parameter, which is listed as 8,760 for medium temperature cases and 8,395 for low temperature cases. Units will typically have some form of downtime during the year for maintenance. If supported documentation is not available, an expert panel should determine the Annual Fan Operating Hours value for low- and medium-temperature areas. This deficiency causes a change of status to Under
Review.
Additional Considerations.
1) Since this measure does not rely on external codes, standards, or efficiency specifications, the measure sunset criteria should be set to 5 years after the RTF decision to move the measure to
“Active” status.
2) The RTF should reconsider the use of or the definitions for the Motors per Controller measure identifier since revised inputs are likely to change the cost-effectiveness thresholds.
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