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Analysis of Refrigerant Use for AC Equipment Maintenance

By: Theresa Pistochini, P.E., Member ASHRAE; Roger Silveira; Derrick Ross, Associate Member ASHRAE; Robert McMurry; Adarsh Umarani

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©2022 This excerpt taken from the article of the same name which appeared in ASHRAE Journal, vol. 64, no. 10, October 2022.

About the Authors
Theresa Pistochini, P.E., is a research and development engineering manager at the UC Davis Western Cooling Efficiency Center (WCEC). Roger Silveira is the director of facilities maintenance and operations at East Side Union High School District Derrick Ross assisted wtth this project as a research and development engineer at WCEC; he is currently an energy coach at Cascade Energy, Inc. Robert McMurry is a research and development engineer at WCEC. Adarsh Umarani assisted with this project as a student assistant at WCEC; he is currently a manufacturing engineer at Aehr Test Systems.


Understanding refrigerant emissions from air-conditioning (AC) equipment is critical for accurately estimating its global warming impacts. The goal of the study described in this article was to develop a primary data collection method to estimate average refrigerant emission rates of R-22 and R-41 OA in AC equipment by examining historical refrigerant used relative to the initial refrigerant charge of the AC equipment inventory. The methodology was applied to estimate annual refrigerant emission rates at one school district with 1,853 pieces of small AC equipment. The methodology was developed to be easily extended to additional equipment inventories such that the available data set could be expanded by future data collection and research.

A variety of reputable sources have reported a range of typical values for refrigerant emissions in small AC equipment. The Intergovernmental Panel on Climate Change (IPCC) publication "2006 IPCC Guidelines for National Greenhouse Gas Inventories" estimates 1% to 10% annual emissions rates for residential and commercial AC, including heat pumps, with lower values for developed countries and higher values for developing countries.1 Nonducted residential split AC, ducted residential split AC, and ducted commercial split AC and packaged AC were all reported to have a 4% to 5% annual emissions rate.2 A report from United Nations Environment Programme in 2010 found that various countries have demonstrated a reduction in refrigerant emissions from air-conditioning and refrigeration equipment through design changes from 10% to 15% down to 5% per year.3


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