was due to improved compressors. This assumption derives from the opinions of two different expert analysts (Baxter, 2001). The assumption is reasonable since the corresponding improvement in compressor efficiency was 50 percent and the DOE compressor contractor seemed to lead the field and pull improvements from other manufacturers.
The cost of efficiency improvements to the consumer was assumed to be $170 (Rosenfeld, 1991), and half this cost was assumed to be for the improved compressor. Thus, the cost of the compressor improvements was $85, which is likely too high for the reasons mentioned above. The lifetime of the refrigerators was assumed to be 20 years (Rosenfeld, 1991).
For each year from 1981 through 1990, the annual energy use reduction compared to 1979 was used to calculate the energy savings due to advanced compressors and the total life-cycle savings for units sold that year. From these savings and the national average residential cost of electricity, the life-cycle energy cost savings were calculated for units sold in each year. From this cost savings, the incremental cost of the compressors was subtracted and the net life-cycle savings were calculated and summed over the decade. The result was about $9 billion in energy cost savings and primary energy savings of about 2.2 Q. In addition, the committee applied its 5-year rule. To calculate realized benefits, half of the efficiency savings per unit in 1981 was applied to the units sold in 1986, and for 1987, half the energy savings per unit in 1982 was multiplied by the number of units sold in 1987, and so on for each year to 1990. Life-cycle energy savings were subtracted for each year from the previous savings for that year and the results summed to obtain a cumulative effect. This reduced net energy savings attributable to improved compressors from 2.2 to 1.3 Q, and the energy cost savings were reduced from $9 billion to $7 billion. The simple payback varied over a period beginning in 1981 for about 10 years and lessened to about 5 years in 1990.
The analysis assumed that half the annual energy use reduction measured by the industry for models sold in a particular year was due to improved compressors. Additional assumptions were made for the consumer cost of buying improved compressors. Nevertheless, the committee believes the cost savings and energy savings are reasonably attributable to improved compressors, and that the DOE R&D investment played an important role in bringing continuously improving compressors to market.
From 1990 through 2005, improvements in refrigerator-freezers have continued and will continue to occur. A princi-