Hey Mr. Green, Should we replace our 1990 refrigerator? I know new models are much more efficient, but my husband asked about the environmental costs of replacing the old one before it conks out: Yes, we'd save energy, but what about the downside of removing and disposing of the old fridge, plus manufacturing the new one? —Gwen in Syracuse, New York

I applaud your husband's thoughtful questions, even if he's just deploying them to avoid shelling out money for a new fridge. Fortunately, you can tell him to chill. The average refrigerator today uses a third less energy than those of 15 years ago, thanks to federal regulations mandating greater efficiency. (Take that, you folks who whine about "burdensome regulations.") Because of this improvement, the energy used to dispose of a fridge as old as yours and to make a new one is recovered in just a few years' operation. Plus about 80 percent of the material in old refrigerators gets recycled. Before you buy, take a look at models bearing the EPA's Energy Star rating (energystar.gov), because they use at least 15 percent less energy than federal regulations require. (The refrigerator retirement calculator on the Web site will show you how much you can save.) Some utilities will even offer you a rebate on 'em.

One more thought: Like so many other things in the United States, from Big Gulps to trophy homes, refrigerators have developed a deplorable tendency toward gigantism and superfluous gadgetry. About all that's missing from the most Hummer-esque fridges is a robot to open your beer and chirp "Cheers" in one of a thousand programmable languages. You can easily end up paying four to five times more for space and features you'll never use. If you buy a modest 15-cubic-footer, you'll recoup its purchase price during its lifetime because of its miserly power demands.

Hey Mr. Green, Can campers still cook over a campfire, or should we use a Coleman stove? —Karen in Los Altos, California

The campfire is part of Americana, with cowboy actors staring into the flames and feeling lonely, philosophical, horny, or homicidal while wolves howl in the distance. But you are not John Wayne or Clint Eastwood or even Roy Rogers, and you should not rely on campfires for cooking--especially in dry areas or regions that are heavily used. Deadwood plays an important role in an ecosystem's life cycle, providing nutrients to the land as well as habitats for small animals, insects, and microorganisms. In many cases, land managers forbid fires, so check with the officials first. Take that Coleman or other stove along, and be sure you know how to use it properly.

If there's plenty of fuel, an occasional campfire is OK, as long as it complies with the cardinal rule of outdoor activity: Leave no trace. That means no carbon scars on the ground, no way for anybody but the shrewdest Old West marshal to know you were there. You can learn how from a Colorado-based organization called Leave No Trace or (800) 332-4100, or get advice from the affiliated National Outdoor Leadership School, at www.nols.edu or (800) 710-6657, ext. 3.

ON THE WEB Read more Mr. Green and submit your own questions at sierraclub.org/mrgreen, or mail them care of Sierra at 85 Second St., 2nd Floor, San Francisco, CA 94105.

Illustration by Melinda Beck; used with permission.