Life Cycle Optimization of Residential Air Conditioner Replacement

Each component was assigned to an appropriate NAICS category so an energy and GHGmultiplier could be obtained for that category using the Department of Commerce 1997 dataset(Carnegie Mellon University Green Design Institute, 2008). It was calculated that the cost of thecoils was composed of 55% copper costs and 45% aluminum costs based on an assumption ofequal mass proportions and a 20% higher price for copper per unit of mass than for aluminum(USGS, 2009). All the other components were assigned to a single category as shown in Table3.1.Table 3.1: CAC Components and Designated NAICS CodeComponentNAICS CodeOutdoor Unit Coil Materials 331421 Copper Rolling, Drawing, and Extruding331315 Aluminum Sheet, Plate, and Foil ManufacturingElectrical Materials 331422 Copper Wire (except Mechanical) DrawingMisc Materials 33272 Turned Product and Screw, Nut, and Bolt ManufacturingFan Materials 333996 Fluid Power Pump and Motor ManufacturingCabinet Materials 331221 Rolled Steel Shape ManufacturingPlumbing Materials 331421 Copper Rolling, Drawing, and ExtrudingCompressor Materials 333912 Air and Gas Compressor ManufacturingIndoor Unit Coil Materials 331421 Copper Rolling, Drawing, and Extruding331315 Aluminum Sheet, Plate, and Foil ManufacturingElectrical Materials 331422 Copper Wire (except Mechanical) DrawingMisc Materials 33272 Turned Product and Screw, Nut, and Bolt ManufacturingFan Materials 333996 Fluid Power Pump and Motor ManufacturingCabinet Materials 331221 Rolled Steel Shape ManufacturingPlumbing Materials 331421 Copper Rolling, Drawing, and ExtrudingDirect Labor (incl. benefits)81141 Home and Garden Equipment and Appliance Repair andMaintenanceOverhead (incl. benefits)55111 Management of Companies and EnterprisesThe energy and GHG results from each of these components were summed together to createthe life cycle inventories. The burdens for producing refrigerant were considered in a separateanalysis presented in Section 3.1.4.3.1.2 Process LCIThe second approach to estimating the production of the CAC was based on a process LCAapproach. The burdens associated with the material production, the fabrication of thosematerials into components, and the final assembly of the products were considered.Outdoor UnitIn order to estimate the material composition of the outdoor unit, a retired unit was dissembledand the components were weighed to determine their mass. The unit was a 3‐ton, 10 SEER unit(Byrant Model 561CJ036‐C). Based on the model revision number, it is estimated that this unitwas likely manufactured around 2001. Table 3.2 shows the breakdown of the weights of thevarious components. The refrigerant used in the unit was considered separately.