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Federal Register / Vol. 86, No. 58 / Monday, March 29, 2021 / Rules and Regulations
AHAM generally agreed with the waivers, which included the weighting factors above. AHAM, No. 13 at p. 4
ASAP, the Joint Commenters, and Rice expressed concern that DOEs proposed approach would not reflect seasonal efficiency, claiming it would result in underweighting performance at the higher outdoor temperature conditions and overweighting performance at the lower temperature conditions. ASAP commented that, under the weighted-average calculation proposed in the June 2020 NOPR
delivered cooling from an hour of operation under the 95 F test condition was equal to that under the 82 F test condition, even though the delivered cooling, and energy consumption, at the 95 F test condition is greater. ASAP, Public Meeting Transcript, No. 12 at pp.
3536 Rice suggested replacing the proposed performance weighting factors based on fractional bin hours with fractional delivered cooling output per bin because the proposed approach ignores that, at the lower ambient temperature bins, the delivered amount
of cooling is proportionally lower 50
percent at 82 F ambient. Rice also recommended replacing the 92 F test condition with a 75 F test condition, to supplement the 82, 87, and 95 F
variable-speed ratings tests, to represent the missing 40 percent of cooling load, as discussed in section III.C.2 of this document. For the proposed 75 F test condition, Rice stated the variable-speed unit should be run at a reduced speed level to obtain 30 percent of rated capacity at 95 F ambient temperature.
Rice expressed further concern that PAFs based on the wrong weighting factors and an inappropriately narrowed cooling range will give too much credit to variable-speed designs that operate best in this narrowed range, and may inadvertently favor variable-speed designs that seek ratings advantage by boosting performance at the 82 F and higher test conditions at the expense of lower ambient temperature performance. Joint Commenters, No. 15
at p. 2; Rice, No. 17 at pp. 12
DOE agrees that the cooling delivered by room ACs at lower outdoor
temperature test conditions is proportionally lower than at the appendix F single-speed test condition.
Thus, calculating the test condition weighting factors using fractional delivered cooling output per temperature bin, as suggested by Rice, applied to the set of test conditions required by DOE above, would improve the representativeness of the test procedure. This change would not increase the testing burden as compared to the test procedure required under the waivers. While this change would diverge from the industry-accepted test procedure AHAM RAC12020, the deviation is justified due to the improvements in representativeness of the test procedure. Therefore, DOE is adopting the test condition weighting factors shown in Table III7, calculated by adjusting the weighting factors in Table III6 by the expected cooling load at each condition based on the building load calculation in AHRI Standard 210/
240 Equation 11.60, and normalizing the resulting values so the final weighting factors sum to 1.0.

TABLE III7FINAL RULE TEMPERATURE CONDITION WEIGHTING FACTORS
Evaporator inlet air, F

Test condition
Dry bulb Test Test Test Test
Condition Condition Condition Condition
1 2
3 4

7. Weighted CEER and Performance Adjustment Factor The final step in the waivers and the June 2020 NOPR proposed approach is to calculate the PAF, representing the improvement over a theoretical comparable single-speed room AC
resulting from the implementation of a variable-speed compressor. 84 FR 20111
May 8, 2019; 85 FR 31481 May 26, 2020; 85 FR 35700, 35712 Jun. 11, 2020. The PAF is calculated as the percent improvement of the weightedaverage CEER value of the variablespeed room AC compared to the weighted-average CEER value of a theoretical comparable single-speed room AC under the four defined test conditions.
After calculating the PAF, it is added to one and the sum is multiplied by the CEER value of the variable-speed unit when tested at the 95 F test condition according to appendix F, resulting in the final CEER metric for the variablespeed room AC. By adjusting the variable-speed room AC CEER values to
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Condenser inlet air, F

Wet bulb 80
80
80
80

Dry bulb 67
67
67
67

be comparable to single-speed room AC
CEER values, DOE expects that consumers will have the information they need to understand the relative efficiency of both types of room AC. In the June 2020 NOPR, DOE proposed calculations to determine a PAF, which would adjust the CEER of a variablespeed room AC to appropriately account for its efficiency improvements relative to a theoretical comparable single-speed room AC under varying operating conditions. 85 FR 35700, 35712 Jun. 11, 2020.
Rice proposed a new method to calculate the weighted average CEER in which the individual weighting factors are divided by the tested CEER values, summed, and the reciprocal of the sum is the weighted CEER value. Rice noted that the result of this formulation exactly matches the result of the conventional binned method from AHRI
210/240. Rice, No. 19 at pp. 34
Rice provided little explanation or evidence supporting this new calculation approach and whether it
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Wet bulb 95
92
87
82

CEER
weighting factor
75
72.5
69
65

0.08
0.20
0.33
0.39

provides more representative results than the approach proposed in the June 2020 NOPR, beyond indicating the result matches that of the binned method in AHRI 210/240. DOE notes that the calculation approach prescribed in the waivers and proposed in the June 2020 NOPR is the same approach specified in the AHAM RAC12020, which is the latest version of the industry standard specific to room ACs.
Therefore, DOE is adopting the PAF and weighted CEER calculations proposed in the June 2020 NOPR that align with AHAM RAC12020 and the waivers granted to date.
8. Air-Enthalpy Test Alternative DOE recognized the additional test burden associated with testing variablespeed room ACs at multiple test conditions as proposed. In an effort to minimize that additional test burden, DOE initially provided for an optional test in the interim waiver granted to LG
that allowed for use of the air-enthalpy method. 83 FR 30717 Jun. 29, 2018;

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