DAVID HOVEY junior runs his hands over the steel beams of his home, and smiles. Tucked on a hillside in Scottsdale, Arizona that overlooks Phoenix, the property is stunning. It is made entirely of glass and recycled steel. The floor is elevated, leaving intact a 150-year-old ironwood tree. Overhangs keep out the sun. The building is environmentally friendly, but also marketable. Mr Hovey, who runs an architectural company called Optima, thinks many people will want a house just like this.

America is now enamoured of all things green. A study by the National Association of Home Builders (NAHB) found that some 90% of home-builders are now using green ideas. In 2005 the study found a 20% increase in the number of new homes that were environmentally responsible: water-efficient, energy-efficient, built of nature-friendly materials. Last year, the figures were up another 30%.

Green building has become big business. Banks such as Bank of America are adding more green financing packages. Shops selling green building supplies are springing up, as are giant shows. The world's largest exhibition for residential builders is West Coast Green, held in San Francisco. Last September almost 9,000 attended; 4,000 more are anticipated this year. In its honour San Francisco has proclaimed next week “West Coast Green Week”. Christi Graham, the president of West Coast Green, says lower building costs are helping the movement. It used to cost at least 15% more to build using eco-friendly ideas and products, but today they add only 1-3% to the cost of construction, she says.

Media attention helps, too. Al Gore's documentary on global warming, “An Inconvenient Truth”, helped get Hollywood on board. Last summer Brad Pitt teamed up with Global Green, a non-profit group, in a contest to design environmentally friendly homes for New Orleans. In April Robert Redford's series on ecology and green living was aired. Vanity Fair, Newsweek, Forbes and Fortune magazines have run green issues and Entertainment Weekly, a Hollywood monthly, featured Al Gore on its cover.

All this has helped Americans see that green building is easy, rewarding and responsible. The lesson is being learned in Scottsdale, a place whose extraordinary growth in recent decades has often meant swimming pools and green lawns somehow engineered in the desert. At Camelview Village, a multi-family development designed by Mr Hovey's father, who is also an architect, a “desert garden” covers the roof of each house. It is made of plants that require minimal watering, keep the roof cooler than black roof tiles and absorb lots of carbon dioxide. With 16 months to go until the complex is finished, 586 of the 709 units have been sold already. At Sterling Ridge, the Scottsdale property, solar panels and energy efficient glass will keep windows cool in the searing Arizona summers. The power savings are phenomenal, Mr Hovey junior says.

Suppliers of building materials and furniture are now scrambling to give green consumers what they want. There is heavy demand for things such as oriented strand board, which wastes less wood and uses trees such as aspen and poplar that grow fast. Bonded Logic in Chandler, Arizona, sells insulation made from shredded denim, a good mould-resistant alternative to fibreglass. Rastra, a company based in Scottsdale that makes concrete from recycled styrofoam, increased its sales by 385% between 2002 and 2005 and is looking for more American factories.

Lack of uniform standards is a problem. One company selling hydrochloric acid for etching cement floors reckoned that, because it was in gel form and could legally be washed down the drain, the product was environmentally friendly. And paint manufacturers are creating their own green labels instead of complying with regulations.

The US Green Building Council, for its part, is helping by expanding its energy-efficiency rating system from commercial properties to homes. This is the first voluntary national green-building standard; already, 7,500 homes and 330 builders are taking part in the pilot scheme. Home- and building-owners receive credits for green materials used, which can then earn them lower mortgage rates from banks and tax incentives from state and local governments. The NAHB has also launched and trademarked its own national green-building standard.

Fans like Mr Hovey junior need no encouragement. As the sun dips over the Phoenix hills he surveys his masterpiece once more. “Green building”, he says, “is just the way to build.”