UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

NATIONAL VEHICLE AND FUEL EMISSIONS LABORATORY

2565 PLYMOUTH ROAD

ANN ARBOR, MICHIGAN 48105-2498

 

 

MEMORANDUM

SUBJECT: AC17 Results from USCAR Testing Which Demonstrate the Effect of A/C Load Reduction 

on CO2 Emissions

FROM: Brian Nelson

TO: Docket EPA-HQ-OAR-2010-0799

DATE: August 13, 2012

______________________________________________________________________________

United States Council for Automotive Research (USCAR) members Ford, General Motors, and 

Chrysler conducted many environmental chamber tests throughout the multi-year process of 

assisting EPA and CARB in the development of the new A/C test cycle, AC17. As part of the 

test programs that each manufacturer conducted, there was an effort, where possible, to 

determine if CO2 emissions effect of A/C efficiency-improving (and by extension, A/C loadreducing) technologies and control strategies could be observed using the new test cycle. It had 

been noted that the SC03 test procedure, which is primarily a short-duration, high-A/C-load 

cycle for measuring HC, CO, and NOx emissions, was not adequate for the purpose of measuring 

relatively small changes in A/C related CO2 emissions. Therefore, USCAR, EPA and CARB 

initiated a study in April of 2010 to develop a new cycle and test procedure.

The tests were conducted at the Ford, GM and Chrysler laboratories in 2010-2012, and are still 

underway as of the writing of this memo. Results were presented to the USCAR members at 

scheduled meetings, and to EPA and CARB participants. The results of tests are still preliminary 

in that these are “developmental”, often conducted on “development” vehicles. Furthermore, 

some of the tests were conducted under conditions that may not match those that are in the LD 

GHG final rule. Therefore the results should not be used to quantify the magnitude of the effect 

of any particular technology. However, they do (qualitatively) demonstrate that the AC17 cycle 

is capable of detecting the lower A/C-related CO2 emissions which result from the incorporation 

of some A/C efficiency-improving technologies. In all six cases where the effect of a single 

efficiency-improving technology was isolated and compared to a base case (without the 

technology), the CO2 emissions were measurably lower for the improved technology.

EPA is grateful for USCAR participation in this extensive test program. This memo only shows 

some of the preliminary results of USCAR testing, and does not represent any of the opinions of 

the USCAR members. 

OFFICE OF

AIR AND RADIATION
Effect of SOLAR FILM on AC17 Test Results:

Mfr. = Chrysler

Vehicle = 2011 Dodge Avenger with and without solar film

Delta AC17 result = 12.0 g/mi lower (442.4 – 430.4 g/mi) on Phase 1 (SCO3 drive cycle) and 

5.3 g/mi lower (256.3 – 251.0 g/mi) on Phase 2 (HWY drive cycle) with Solar Film

Note: “Baseline” condition is A/C OFF
Effect of SOLAR FILM on AC17 Test Results:

Mfr. = Ford

Vehicle = 2010 Fusion with and without solar film

Delta AC17 result = 4.0 g/mi lower on Phase 1 (SCO3 drive cycle) and 1.0 g/mi lower on Phase 

2 (HWY drive cycle) with Solar Film
Effect of SOLAR FILM on AC17 Test Results:

Mfr. = Chrysler

Vehicle = Fiat 500 with and without solar film

Delta AC17 result = 47.3 g/mi lower (337.2 – 289.9 g/mi) on Phase 1 (SCO3 drive cycle) and 

12.4 g/mi lower (231.9 – 219.5 g/mi) on Phase 2 (HWY drive cycle) with Solar Film
Effect of SOLAR REFLECTIVE GLAZING on AC17 Test Results:

Mfr. = General Motors

Vehicle = Cadillac CTS with and without solar reflective glazing

Delta AC17 result = 9.2 g/mi lower (442.8 – 433.6 g/mi) on Phase 1 (SCO3 drive cycle) and 6.7

g/mi lower (277.5 – 270.8 g/mi) on Phase 2 (HWY drive cycle) with Solar Reflective Glazing

Note: “Baseline” condition is ‘solar absorbing’ glazing
Effect of RECIRC and REDUCED REHEAT on AC17 Test Results:

Mfr. = Chrysler

Vehicle = Avenger with and without forced recirc and reduced reheat 

Delta AC17 result = 8 g/mi lower on Phase 1 (SCO3 drive cycle) and 3 g/mi lower on Phase 2 

(HWY drive cycle) with recirc and reduced reheat

Note: “ATC72” data used to calculate delta AC17 result
Effect of COLD STORAGE EVAPORATOR on AC17 Test Results:

Mfr. = General Motors

Vehicle = Buick Lacrosse with and without solar reflective glazing

Delta AC17 result = 24.0 g/mi lower (78.7 – 54.7 g/mi) on Phase 1 (SCO3 drive cycle) and 3.4

g/mi lower (20.0 – 16.6 g/mi) on Phase 2 (HWY drive cycle) with Cold Storage Evaporator

Note: “Hot Start Test” data used to calculate delta AC17 result