单项选择题

Staring longingly into your empty refrigerator at 3 a. m. is about to become a whole lot cheaper. The U.S. Department of Energy recently released new efficiency standards for refrigerators and freezers manufactured after July 1, 2001. To meet these standards, next generation refrigerators must use 30% less energy.
Manufacturers will achieve most of the energy savings through improvements in the compressor—lower-viscosity oil and tighter bearings, for example. Other changes will include thicker insulation, more efficient fans, and increased surface area of the condenser and evaporator coils. Manufacturers will also step up efforts to incorporate smart features, such as sensors that determine when defrosting is needed. "These are evolutionary, not revolutionary, changes," says Len Swatkowski, director of engineering for the Association of Home Appliance of Manufacturers in Chicago.
The appliances will also likely employ a new blowing agent for foam insulation. The current agent—a hydrochlorofluorocarbo—will be banned as of January l, 2003, because of its ozone- depleting properties. Tests of a potential replacement—a hydrofluorocarbon—show that it conveys heat about as well as the old chemical, with less harm to Earth’s ozone layer.
If issues concerning efficiency, toxicity, and large-scale availability can be worked out, manufacturers will likely switch to the new blowing agent at the same time they incorporate the efficiency improvements.
The bottom line: Consumers will reap energy savings of about $20 per year for a typical 20-cubicfoot refrigerator. And although the new refrigerators will cost approximately $80 more, consumers will see significant savings over a refrigerator’s average 19-year life. The new fridges will have the same features and usable space as conventional units
The DOE has now turned its attention to air conditioners, ranges and ovens, clothes washers, water heaters, and fluorescent light ballasts. Within a few years, all will be subject to new energy standards.
Through this passage, the author intends to ______.