NEW YORK (CNNMoney.com) - In most of America, "greens" live on the margins. But, today, the mainstream is embracing many of the home-building techniques, designs and materials greens advocate.

As we celebrate Earth Day, April 22, the National Association of Home Builders reports that green building is near a "tipping point." The green construction industry segment will climb from 2 percent of all residential starts in 2005 to between 5 percent and 10 percent in 2010.

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"The necessity for more energy-efficiency is driving the trend," says Matt Belcher, who runs Belcher Homes in St. Louis and who chaired the Green Home Building Conference there. "Consumers are looking for energy savings."

That has put green builders in demand and led many traditional builders to embrace their earth-friendly side.

What's holding some back is higher perceived costs. But skyrocketing energy prices change the math - homeowners paying $2.70 a gallon for heating oil are more receptive to paying now and saving later.

Many green methods also conserve materials, which appeals to mainstream builders and consumers alike - fewer materials equal lower building costs.

Builders of dome homes, for example, use the shape's inherent strength to "drastically reduce the lumber needed to frame out a building," says Dennis Johnson, owner of Natural Spaces Domes. "A dome uses about a third or even a quarter of the material a conventionally framed house of equal size requires."

Using longer-lasting materials also means less in repair and replacement costs. David Balas, who designed a green house on Bainbridge Island in Washington, topped it with a steel roof that will last for decades.

Other long-lasting materials include fiber-cement siding, natural earth plasters and stone and tile. Balas points out that many of these "new" materials are actually quite old, even ancient. "The Romans used fly-ash in their concrete," he says, just like he did. "It's one-and-a-half times stronger."

Conserving water is often as vital as saving energy. Green homes use water-efficient bath and kitchen fixtures such as low-flush toilets, low-flow shower heads and recycled gray water.

Great water savings can also be made by choosing the right plants for your yard. "Native plants are always the way to go," says architect Roy Prince, who runs the Web site "green homes for sale." In the parched Southwest that often requires xeriscaping, or dry landscaping. Cactus, turf grasses, succulents and other drought-tolerant species can save a tremendous amount of precious water each year compared with that spent to maintain grass and other thirsty plants.

Sustainable harvests have also gone mainstream. Most lumber today is from sustainable forests. And the use of other sustainable materials - bamboo for flooring, for example - are becoming big, according to Prince.

Some of these materials were once thrown away. These include sawdust, which is now recycled into things like fiber-cement siding; wood chips, for composition board; and even small pieces of waste wood, which are finger-jointed together to make things like moldings and door frames.

Then there are the agricultural byproducts, like the straw and chaff left over from grain harvests.

"In California, about 10 or 15 years back, there was a huge excess of straw bales – they were burning them," says Clyde Curry, a Texan who uses the bales for building. "It got people thinking that, way back, these were used to build houses."

Straw bale walls covered in stucco, adobe or other hard surfaces, produce high "R" factors, the measure of insulation efficiency. A typical new home with 4 inches of batt insulation has an R factor of 13. The walls of Curry's creations can go to R-50 or higher.

Green is not only good for the planet, it's good for the body.

According to Balas, traditional wood finishes – milk paints, shallacs and waxes – are coming back because they are much better for sensitive lungs and allergy sufferers than petroleum-based products.

Manufacturers are also making far more environmentally friendly adhesives, so green home builders are more likely to use them.

In fact, green materials, in general, have become much more a part of mainstream building, according to Belcher. Along with green designs and building methods, green materials have become so ubiquitous that even traditional home builders are, sometimes inadvertently, using them regularly. And their prices have dropped.

All this has already had a strong, positive impact on the environment; that should only improve.

"Green," says Prince, "is the wave of the future. We all have to think about being more conservative now."

• A green home is a healthy home.
• Bainbridge Island is one of out "Best Places to Live"