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Federal Register / Vol. 86, No. 58 / Monday, March 29, 2021 / Rules and Regulations
their test mode.26 The California IOUs also cited research conducted at the Bundesanstalt fur Materialforschung und -prufung BAM Federal Institute for Material Research and Testing in Germany, in which all but one of the seven residential mini-split air conditioners with variable-speed equipment that were tested consumed significantly higher energy when consumer-adjustable, built-in controls were used relative to fixed controls i.e., controls that set the compressor speed using a manufacturer-provided remote or code.27 The California IOUs stated that researchers reported many units reverted to on-off cycling operation when the outdoor temperatures were between 77 and 86 F. The California IOUs encouraged DOE to amend the test procedure to improve representativeness and facilitate product comparison with air conditioners tested under appendix M1 28 to 10 CFR part 430. The California IOUs further encouraged DOE, in collaboration with industry and energy efficiency advocates, to update the test procedure for room ACs by requiring the measurement of units at the 95 F test condition under their native controls to see the speeds at which the compressors operate to ensure accurate testing.
California IOUs, Public Meeting Transcript, No. 12 at pp. 3033;
California IOUs, No. 14 at p. 4
DOE notes that the findings of the 2019 Appliance Standards and Rulemaking Federal Advisory Committees Variable Refrigerant Flow Working Group applied to variablerefrigerant flow multi-split air conditioners and heat pumps, which have different applications and typical use cases from room ACs and which typically provide cooling to multiple locations within a home. Based on a review of the market, room ACs are typically marketed for temporary 26 All published documents directly related to the 2019 Appliance Standards and Rulemaking Federal Advisory Committees Variable Refrigerant Flow Working Group test data are available in docket EERE2018BTSTD0003 https regulations.gov/
docket/EERE-2018-BT-STD-0003.
27 Palkowski, Carsten & Schwarzenberg, Stefan &
Simo, Anne. 2019. Seasonal cooling performance of air conditioners: The importance of independent test procedures used for MEPS and labels.
International Journal of Refrigeration. 104. 10.1016/
j.ijrefrig.2019.05.021.
28 Appendix M is the currently applicable DOE
test procedure for central air conditioners and heat pumps. Appendix M1 will become the test procedure mandatory for use for central air conditioners and heat pumps on or after January 1, 2023. Appendix M and appendix M1 contain similar test conditions, so DOEs evaluation of comments relative to appendix M applies equally to appendix M1.

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seasonal installation 29 for the purpose of cooling a single room,30 whereas multi-split systems are permanent and may be used as part of a larger wholehome cooling system. For these reasons, the comparability of the room AC test procedure and the test procedure for multi-split air conditioners was not further considered in this final rule.
During investigative testing, two variable-speed room AC models from different manufacturers performed differently under fixed temperature conditions with the user settings e.g., fan speed, grille position and thermostat setpoint selected in accordance with the appendix F test appendix F setpoint, relative to the fixed controls, as specified in the waivers and proposed in the June 2020
NOPR. When operating under fixed temperature conditions and the appendix F setpoint i.e., the setpoint which resulted in the maximum cooling capacity, per the requirement in ASHRAE 162016, one unit was 10
percent more efficient than when using fixed controls at the 95 F test condition as specified in the waivers. The second unit was 11 percent less efficient when operated under fixed temperature conditions and the appendix F setpoint than when using fixed controls. Based on the observed differences in the room AC performance when using the fixed full compressor speed as compared to the fixed temperature conditions and appendix F setpoint, DOE is requiring the use of fixed chamber temperature conditions with a unit setpoint of 75 F
for the full speed test, as use of this test setup improves representativeness and reproducibility of results. While AHAM RAC12020 requires the use of a fixed full compressor speed set in accordance with manufacturer instructions, as described above, DOE is adopting a revised approach in this final rule to improve representativeness and repeatability. Using a constant temperature test with a thermostat setpoint of 75 F, in place of the fixed full compressor speed, will ensure measured performance reflects the expected performance of the unit when using a common setpoint selected in the 29 Only 14 room AC models on the market have reverse-cycle heating a heating technology implemented in other electric cooling products intended for year-round operation, compared to the 1,825 total room AC models on the market according to DOEs CCMS database, as accessed February 10, 2021. This indicates that room AC are overwhelmingly used for seasonal cooling.
30 Room air conditioners are typically purchased by selecting cooling capacity to match the size of a single room to be cooled. See, for example, the ENERGY STAR buying guidance at: https
www.energystar.gov/products/heating_cooling/air_
conditioning_room.

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field at 95 F and 92 F outdoor temperatures, where DOE expects these units to be operating at full speed.
However, DOE is not requiring the use of fixed temperature conditions, user settings, and thermostat set at 75 F for the 87 F and 82 F outdoor test condition tests, because those tests represent lower cooling load conditions and would require a load-based test to represent expected unit performance at the associated reduced loads without fixing the compressor speed. As discussed in section III.E.1.d of this document, a load-based test is not feasible at this time. Therefore, the reduced outdoor conditions tests are conducted with fixed compressors speeds that are representative of performance at the expected loads at those reduced conditions. The fixed compressor speeds are defined based on the resulting cooling capacity using fixed temperature condition tests and a unit thermostat setpoint at 75 F, as discussed in section III.D of this document.
Therefore, in this final rule, DOE is requiring fixed temperature conditions with a unit thermostat setpoint of 75 F, rather than using manufacturer instructions to fix the compressor speed for variable-speed room ACs at the 95 F
and 92 F test conditions, while requiring that the compressor speed be fixed to intermediate speed at the 87 F
test condition and low speed at the 82 F
test condition, as discussed and defined in section III.D.1.b of this document and in Sections 2.15 and 2.16 in appendix F, respectively.
b. Instructions for Fixing Compressor Speeds Setting and maintaining a specific compressor speed for a variable-speed room AC is not typically possible without special control instructions from manufacturers.
In the June 2020 NOPR, DOE
proposed to require that manufacturers provide in their certification reports the control settings for each variable-speed room AC basic model required to achieve the fixed compressor speed for each test condition, consistent with the approach in the waivers. 85 FR 35700, 35709 Jun. 11, 2020. These include the compressor frequency setpoints at each test condition, instructions necessary to maintain the compressor speeds required for each test condition, and the control settings used for the variable components. Id. DOE received no comments on the proposal.
Due to the change to require that user settings be implemented to achieve maximum cooling capacity when testing at the 95 F and 92 F test conditions, as
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