Cool choices in room air conditioners.(up front: News / Trends / Advice)(Product/service evaluation)

Prices as low as $100 have made room air conditioners an affordable luxury. Research suggests that they also save lives. A study published in the journal Environmental Health Perspectives in 2003 found that on average, heat-related mortality rates in 28 major U.S. cities dropped as air conditioners became more prevalent.

Another reason to buy: The latest use less energy. All of the recently tested picks in our Quick Ratings, which combine performance and value, meet or exceed the 10.7 Energy Efficiency Rating needed to merit the Energy Star for models at least 10 percent more efficient than the minimum standard. Every 0.1 hike in EER means a roughly 1 percent drop in electricity use for similarly sized models.

The most miserly model we've seen: the large Friedrich SS10L10-A, with an EER of 12. It performed very well but costs $700. Recouping the extra cost over a typical $250 unit would take more than 50 years under normal use.

CR's take. All the listed A/Cs excelled at comfort-set on low cool, they provided even temperature and humidity throughout the room. The CR Best Buys give the most heat relief for the dollar. Many models are better at directing air to their left than to their right. The midsized and large Kenmores blow well to their right. So does the small Haier, but it lacks adjustable up/down louvers.

WATCH OUT FOR PORTABLES

A/Cs that roll from room to room and vent through a window may seem like a good alternative where window or wall mounting won't work. But in our tests, three large portable A/Cs delivered less heat relief than their claims suggest.

The Amana AP095R, Everstar MPK-10CR-1, and Frigidaire FAP09EP1Z cost $400 to $500 and are rated about 10,000 Btu/hr., enough to cool some 400 square feet with a regular A/C. Yet none of them supplied even half that cooling power. All have a single exhaust hose, which draws warm air from elsewhere in the house to cool the condenser coils. If you must use a portable, buy one with two exhaust hoses. That type cools coils with outdoor air and should come closer to delivering its rated BTUs.