Emissions of HFC-134a from Light-Duty Vehicles in California

The current refrigerant in mobile air conditioning (AC) systems, HFC-134a (also known as R134a), is a potent greenhouse gas (GHG) with a global-warming potential (GWP) of 1300. Its emissions from 2009 and subsequent model-year (MY) light-duty vehicles may be regulated under the terms of a law (Sec. 43108.5, Health and Safety Code) adopted in California in 2002. To support regulation development, we have estimated direct emissions of HFC-134a from vehicular AC systems in California by a novel, three-prong method that uses: 1) data on the consumption of HFC-134a by California commercial fleets, 2) surveys of vehicle owners on AC system repair incidence, and 3) data on repair incidence among California commercial fleet vehicles. Although these sources do not report direct emission rates of HFC-134a, the data reflect actual leakage integrated over long periods from vehicles in all stages of useful life. Results from the analysis suggest that in California, the typical light-duty vehicle loses approximately 1.4 kg of HFC-134a over a 16-year average lifetime, and HFC-134a emissions in 2003 were approximately 80 grams per vehicle. These results are consistent with the limited data available from emission measurements but less than the estimates annually published by U.S. EPA.