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Tao Zhan, Ph.D.

California Air Resources Board

California’s Regulatory Proposal for Reducing 

Greenhouse Gas Emissions from

Mobile Air Conditioning

MACS Worldwide 2011 Convention and Trade Show

US EPA Regulatory Session

Lake Buena Vista, Florida, January 29, 2011
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Evolution of Regulations

LEV III

2009 

MY

2017 

MY

CA

US EPA Federal Rule

2012 

MY

Mandatory requirements (proposal):

• Low-GWP refrigerant

• Low leak rate

• Indirect emissions limit

New Federal Rule

MAC improvements earn 

credits for GHG emissions

Credit method similar to CA 

Pavley approach via “Rose 

Garden Agreement”

AB 1493 (Pavley)
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LEV III MAC Requirement 1:

GWP ≤ 150 (100% for 2017 MY)

• Benefits

– Provides a nearly 90% direct emission reduction

– Harmonizes with EU’s MAC Directive (Directive 2006/40/EC)

• Potential candidates / SNAP approval: HFC-152a (approved), 

R744 (CO2) (pending), and HFO-1234yf (pending)

• Movement toward use of low-GWP refrigerant

– GM and Aston Martin plan to introduce HFO-1234yf for 2017 or prior 

models

– Chemical manufacturers indicated their ability to provide sufficient 

supply of HFO-1234yf with firm purchase commitment and sufficient 

lead time

– Several stakeholders have expressed concerns about proposed timeline

– A multi-year phase-in as proposed by some stakeholders would delay 

climate benefits, result in larger HFC banks, and cause more potential 

cross-contamination during service
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LEV III AC Requirement 2:

Fleet Average Leak Rate ≤ 9 g/yr

• Low leak rate is important, regardless of refrigerant used

– Maintain efficiency

– Reduce need for maintenance

• Leak rate will be evaluated using SAE J2727-type standards 

for AC using low-GWP refrigerants

• 9 g/yr (refrigerant) is achievable

– 18 g/yr around 2003 MY (US EPA), 50% reduction feasible (I-MAC)

– 14-15g/yr for 2009 MY (Minnesota MAC Leakage Database, CA MAC 

certification programs, Ward’s Auto data), depending on how leak 

rates are averaged

– Some commercially available AC platforms using premium 

technologies are already achieving 9 g/yr

– Some carmakers appear on track for meeting 9 g/yr

– Several stakeholders have expressed concerns about stringency of 

proposed leak rate limit
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LEV III AC Requirements 1 & 2:

Estimated Emission Reduction

Potential emission reduction: ≥ 90% by 2040

Refrigerant Emissions from Light-Duty Vehicles in California

0.0

0.5

1.0

1.5

2.0

2.5

3.0

2010 2015 2020 2025 2030 2035 2040

Calendar Year Emissions (MMTCO2E/yr)

BAU:

Continued use of HFC-134a (GWP=1,430)

HFC Phaseout 1:

MY 2017 & newer, Low-GWP Refrigerant 

(GWP=150)

HFC Phaseout 2:

MY 2017 & newer, Low-GWP Refrigerant 

(GWP=4, if HFO-1234yf is chosen by industry)
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LEV III MAC Requirement 3:

Indirect Emissions Standard

• ARB is proposing to develop a fleet average AC indirect 

emissions standard 

– Evaluate through a Whole-Vehicle Performance Test Procedure

• For LEV III going to the Board this year, ARB will propose initial 

adoption of US EPA’s Idle Test procedure and AC Efficiency 

Credits scheme as a placeholder

– Amend the regulation after developing a performance test procedure 

and an AC indirect emissions standard in ~2 years

– Implementation to begin in 2017

• Performance test benefits

– Able to evaluate all current and new technologies under realistic solar 

load and driving conditions

– Enforceable
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LEV III MAC Requirement 3 (Cont.):

Proposed Performance Test Procedure

SC03 Driving Cycle

• Elements of proposed test procedure:

– Simulated solar load (e.g., 1 hour soak at 850 W m-2)

– Moderate ambient cell conditions (e.g., 250C, 50% RH)

– Transient test cycle (e.g., SC03+HWFET)

– Evaluate AC during both initial cool down and steady state temperature 

control

• Difference between CO2from AC-off cycle and CO2from 

weighted average of AC-on cycles (cool down and steady state) 

must be  the standard
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• California’s new vehicle GHG emission standards for 2017 MY 

and beyond will be incorporated into the Low Emission Vehicle 

regulation (LEV III)

• Mandatory requirements for MAC proposed under LEV III:

– Low-GWP refrigerant

– Limit on leak rate

– Limit on indirect emissions (evaluated by performance test)

• LEV III is under development, and is expected to go to the 

Board in October, 2011. We are still accepting comments on all 

aspects of the proposal.

Summary
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Direct Emissions

• Research Division 

– Dr. Tao Zhan (staff lead), (916) 445-9495, tzhan@arb.ca.gov

– Dr. Tao Huai (manager), (916) 324-2981, thuai@arb.ca.gov

Indirect Emissions

• Mobile Source Control Division

– Dr. Leela Rao (acting manager), (626) 350-6469, lrao@arb.ca.gov

ARB Contacts

For more information, visit

http://www.arb.ca.gov/cc/hfc-mac/hfc-mac.htm

http://www.arb.ca.gov/msprog/levprog/leviii/leviii.htm