Can a luxury home really be green? The question is a topic of debate among conservationists, especially since — until recently — "luxury" has typically meant sprawling complexes that consume large amounts of resources while housing relatively few people.

Upper-end buyers tend to put more of a premium than do other groups on the home's relation to its surroundings. "The home has to fit the site," says Downes. In other words, it has to communicate "green" to everyone who sees it.

However, luxury green buyers also want to keep amenities like the Sub-Zero refrigerator and the Wolf range. They typically want to hang on to high-end home theater systems and heated pools, neither of which is particularly green because they consume lots of energy. To offset, these buyers respond favorably to products that offer extreme energy savings: super-insulated, super-tight walls; recycled, long-lasting metal roofs; and solar panels, wind turbines, rainwater harvesting and irrigation systems, and geothermal heat.

Be says luxury green buyers also want materials that aren't commonly found in lower-priced homes. For instance, granite countertops and hardwood floors don't interest them. Instead, these are the people who will spend $250 per square foot on 100 percent recycled glass countertops, and who enjoy being able to tell the story behind their wood floors that were reclaimed from a local historic building. "They want recycled metal tile backsplashes or tiles made from unusual materials, such as coconut shells," Be says. "It's anything which makes the home stand out and pop visually."

Downes agrees. "Granite is overdone," he says. "There are far more exciting choices now. Stainless steel, concrete, recycled glass and wood counters are all fine where appropriate. A lot of designers say they'd be happy never to see another piece of granite again."