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Federal Register / Vol. 86, No. 58 / Monday, March 29, 2021 / Rules and Regulations
burdensome. Therefore, DOE is not adopting boost compressor speed provisions in appendix F.
4. Capacity and Electrical Power Adjustment Factors In the waivers and proposed June 2020 NOPR approach, a capacity adjustment factor is used to estimate the increased cooling capacity and reduced electrical power draw of a single-speed room AC at lower outdoor temperature conditions, using a linear extrapolation based on the measured capacity and power draw at the 95 F test condition, respectively. 85 FR 35700, 35711 Jun.
11, 2020. To determine these two adjustment factors, DOE used the MarkN model 32 to model room AC
performance at reduced outdoor temperature conditions. Id. These modeling results suggested linear capacity and electrical power adjustment factors of 0.0099 per F and 0.0076 per F, respectively. Id.
To confirm the validity of these modeled adjustment factors, DOE tested a sample of 14 single-speed room ACs at a range of reduced outdoor temperature test conditions 92 F, 87 F, and 82 F and compared the predicted values of cooling capacity and electrical power with the measured values at each test condition. The results generally indicated close agreement i.e., less than 5 percent difference on average between the modeled cooling capacity
based on an adjustment factor of 0.0099
per F and the measured capacity at each test condition, and between the modeled electrical power draw based on an adjustment factor of 0.0076 per F and the measured electrical power draw at each test condition. DOE
tentatively determined that the average difference of less than 5 percent between the modeled values and the experimental values confirmed the validity of these modeled adjustment factors. Therefore, in the June 2020
NOPR, DOE proposed to use the modeled adjustment factors of 0.0099
per F and 0.0076 per F for capacity and electrical power, respectively, to calculate the theoretical comparable single-speed room AC performance at reduced outdoor temperature test conditions. 85 FR 35700, 35711 Jun. 11, 2020.
NEAA expressed concern about DOEs proposal to use linear capacity and electrical power adjustment factors to predict the capacity of fixed speed equipment at lower outdoor temperatures. NEAA commented that, while the order of magnitude of the error is small, the factors chosen consistently overpredict capacity and underpredict energy use for singlespeed equipment. NEAA further commented that this will reduce the CEER ratings of variable-speed room ACs. NEAA recommended modifying the capacity and electrical power
adjustment factors so that they do not overpredict capacity and underpredict energy use consistently. NEAA, No. 16
at p. 5
DOE disagrees with NEAAs assessment that the modeling factors consistently overpredict capacity and underpredict energy use. DOE observed that the modeling factors were able to predict capacity and energy use in the test sample within four percent on average, and often more accurately.
Additionally, there was no consistent trend in the variation in capacity or energy use predictions i.e., some predictions were higher than the actual, some were lower. Therefore, DOE is adopting as proposed the capacity and electrical power adjustment factors of 0.0099 per F and 0.0076 per F, respectively.
5. Cycling Loss Factors In the June 2020 NOPR, to represent the cycling losses of a theoretical comparable single-speed room AC at reduced outdoor temperature test conditions and expected reduced cooling loads, DOE identified cycling loss factors CLFs to apply to the interim CEER values at each of the four cooling mode test conditions for a theoretical comparable single-speed room AC. 85 FR 35700, 35711 Jun. 11, 2020. Table III4 shows the CLFs for each of the four test conditions.

TABLE III4JUNE 2020 NOPR PROPOSED CYCLING LOSS FACTORS
Evaporator inlet air, F

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

These CLFs were based on the default cooling degradation coefficient Cd in Section 11.2 of AHRI Standard 210/
240. The CLF at the 82 F test condition for a theoretical comparable singlespeed room AC is consistent with the default Cd of 0.25, which corresponds to a part-load cycling loss factor of 0.875, as determined in Section 11.2 of AHRI
Standard 210/240. The remaining CLFs for the other test conditions are consistent with linear interpolation between the CLF of 0.875 at the 82 F
test condition and the CLF of 1.0 at the 32 MarkN is an energy modeling program developed in an ECS direct final rule for room ACs that DOE published on April 21, 2011. 76 FR 22454.

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Condenser inlet air, F

Wet bulb 80
80
80
80

Dry bulb 67
67
67
67

Cycling loss factor
Wet bulb 95
92
87
82

75
72.5
69
65

1.0
0.971
0.923
0.875

95 F test condition, at which no cycling is expected.
Thus, DOE proposed to implement CLFs consistent with the default Cd in AHRI Standard 210/240, to represent the expected performance of a theoretical comparable single-speed room AC at reduced outdoor temperature test conditions. Id.
AHAM commented that while DOE
cited Section 11.2 of AHRI Standard 210/240 and a Cd of 0.25, AHRI
Standard 210/240 includes a Cd of 0.20
for Single Stage Systems in Section 6.1.3.1.1. AHAM recommended that
DOE ensure it uses the most recent version of the standard and the correct Cd. AHAM, No. 13 at p. 5
The California IOUs, NEAA, and Rice expressed concern about the proposed default Cd of 0.25. California IOUs, Public Meeting Transcript, No. 12 at p.
30; NEAA, No. 16 at p. 5; Rice, No. 17
at pp. 34 NEAA commented that room ACs may cycle more than central air conditioners due to improper sizing, further pointing to a need for additional testing. NEAA, No. 16 at p. 5 Rice commented that Figure III.1 in the June 2020 NOPR suggested that the Cd for the
The MarkN program is an update of an adaptation to the Oak Ridge National Laboratory Mark III Heat
Pump program for modeling room AC cooling performance.

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