Opportunities for improving the energy efficiency of window-type room air conditioners.

As required by the National Appliance Energy Conservation Act (NAECA), minimum energy efficiency standards ranging from 8.0 to 9.0 EER went into effect for window-type room air conditioners on January 1, 1990. But by incorporating commonly used technologies such as high-efficiency rotary compressors, grooved refrigerant tubing, slit-type fins, subcoolers, and permanent split capacitor fan motors, 10.0 EER efficiency levels can be achieved for the most popular classes of room air conditioners without having to increase chassis size. Even greater efficiency increases can be realized with brushless permanent magnet fan motors, enlarged heat exchanger coils, and variable speed compressors. Efficiency increases were estimated through the use of a calibrated computer simulation model. To assess the cost-effectiveness of the above design options, their impact on manufacturing cost was estimated with data supplied by both room air conditioner manufacturers and component suppliers. New minimum efficiency standards set at levels requiring approximately a 10.0 EER for the most popular classes would result in the following projected benefits: (1) national energy savings of 0.69 Quads over the period 1999-2030, (2) S02, NO., and C02 emission reductions of Ill kt, 104 kt, and 57 Mt, respectively, over the period 1999-2030, and (3) peak demand savings of 2.17 GW by the year 2025. For tlie consumer, a" 10.0 EER" minimum standard yields the lowest life-cycle cost and the corresponding payback period is no greater than six years for the most popular classes.