Life Cycle Optimization of Residential Air Conditioner Replacement

RefrigerantsAs described in Section 3.3, the leakage was assumed to decrease from 4% to 2% of refrigerantmass during the time period of the study. In addition, the refrigerant was modeled ascompletely changing over from R‐22 to R‐410a by 2010. Figure 4.2 shows the changeovermodel based on estimates from the industry (Zellmer, 2008).100%90%80%70%60%50%40%30%20%10%0%2002 2003 2004 2005 2006 2007 2008 2009 2010R‐410aR‐22Figure 4.2: Growth in R‐410a Market Share of Residential CAC Market4.3 Energy IntensityOver time the energy required to produce goods generally decreases as processes arestreamlined, waste is reduced, and new more efficient manufacturing technologies emerge. Amethod for estimating the changes in energy intensity of basic materials was utilized by Kimwhile modeling the life cycle of a mid‐sized car (2003). These values were used in this study forthe period from 1985 to 1998. Values after 1998 were updated with actual data that hasbecome available since Kim’s work. The same techniques for estimating future energyintensities were also used to extend the index to 2025. A more detailed description of thevarious data sources used and the resulting material index is given in the Appendix. Thisdecrease in the energy and GHG intensity of the raw materials used to make the CACcomponents counteracts the tendency of increasing environmental burdens due to the need tomake larger, more energy efficient components.The proportion of energy required and GHG emitted from the production of each major type ofraw material and from the manufacturing of the components was found from the SimaProanalysis of the outdoor unit and indoor unit. This allowed for scaling of the energy and GHGburdens associated with the CAC components for each model year based on the changingenergy intensity of the raw materials and manufacturing in that particular year.