['Air Programs']
['Mobile Emission Sources']
08/01/2024
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Manufacturers may generate credits applicable to the CO 2 fleet average program described in §86.1865-12 by implementing specific air conditioning system technologies designed to reduce air conditioning refrigerant leakage over the useful life of their passenger automobiles and light trucks (including MDPV). Calculate credits for each air conditioning system used to generate CO 2 credits. This section applies starting with model year 2031.
(a) Calculate an annual rate of refrigerant leakage from an air conditioning system in grams per year for refrigerants with GWP at or below 150 according to the procedures specified in SAE J2727 SEP2023 (incorporated by reference, see §86.1).
(b) Determine the CO 2 -equivalent gram per mile leakage reduction separately for passenger automobiles and light trucks, as follows:
(1) Calculate the leakage credit to the nearest 0.1 g/mile using the following equation:
Equation 1 to Paragraph (b)(1)
Where:
MaxCredit is the maximum per-vehicle value of the leakage credit. Use 1.6 g/mile for passenger automobiles and 2.0 g/mile for light trucks.
GWPREF means the global warming potential of the refrigerant as indicated in paragraph (e) of this section.
HiLeakDis is the high leak disincentive, as determined in paragraph (b)(2) of this section.
(2) Calculate the high leak disincentive, HiLeakDis, using the following equation, except that if the calculated result is less than zero, set HiLeakDis equal to zero:
Equation 2 to Paragraph (b)(2)
Where:
K = a constant. Use 1.6 for passenger automobiles and 2.0 for light trucks.
LeakScore means the annual refrigerant leakage rate as described in paragraph (a) of this section, expressed to the nearest 0.1 grams per year. If the calculated rate for passenger automobiles is less than 8.3 grams/year (or 4.1 grams/year for systems using only electric compressors), use 8.3 grams/year (or 4.1 grams/year for systems using only electric compressors). If the calculated rate for light trucks is less than 10.4 grams/year (or 5.2 grams/year for systems using only electric compressors), use 10.4 grams/year (or 5.2 grams/year for systems using only electric compressors).
LeakThreshold = 11.0 or [ Refrigerant Capacity × 0.015], whichever is greater, where Refrigerant Capacity is the maximum refrigerant capacity specified for the air conditioning system, in grams.
(c) Calculate the total leakage reduction credits generated by the air conditioning system separately for passenger automobiles and light trucks to the nearest whole megagram using the following equation:
Equation 3 to Paragraph (c)
Where:
Leakage = the CO 2 -equivalent leakage credit value in grams per mile determined in paragraph (b) of this section for passenger automobiles or light trucks.
Production = The total number of passenger automobiles or light trucks, produced with the air conditioning system to which to the leakage credit value from paragraph (b) of this section applies.
VLM = vehicle lifetime miles. Use 195,264 for passenger automobiles and 225,865 for light trucks.
(d) Include the results of paragraph (c) of this section in your credit totals calculated in §86.1865-12(k)(5).
(e) Calculate leakage credits using values for refrigerant global warming potential ( GWPREF) as follows:
(1) Use the following values for the specific refrigerants:
(i) For HFC-152a, GWPREF = 124.
(ii) For HFO-1234yf, GWPREF = 1.
(iii) For CO 2 , GWPREF = 1.
(2) EPA will assign values for GWPREF, up to a value of 150, for other refrigerants upon request.
[89 FR 28196, Apr. 18, 2024]
['Air Programs']
['Mobile Emission Sources']