Soaring energy costs and increased concern about the environment are spurring US builders to step up building homes that use less energy and water.

More than 30 affordable homes being built during a Habitat for Humanity project in Los Angeles include materials designed to reduce energy costs and save the new homeowners money.

'Green building certainly is becoming more mainstream within the affordable housing community,' said Ted Bardacke, senior programme associate with Global Green USA, an environmental group that works with housing developers.

Homes being constructed during the Habitat project, an annual event hosted by former US President Jimmy Carter to build homes for lower-income families, include solar panels on the roof that generate energy, double-pane windows and energy-saving lights and ceiling fans.

This year, the Carter project is seeking LEED (Leadership in Energy and Environmental Design) certification -- a US standard that identifies buildings that are environmentally responsible and have lower operating costs.

'Energy over time is only going to get more expensive,' Bardacke said. 'In serving low-income families, we have to recognize that a truly affordable house is not just a house that's affordable to buy, but is more affordable to operate.'

Appliance maker Whirlpool is donating water- and energy-saving washing machines and refrigerators to the Habitat homes, while Dow Chemical provided exterior housewraps and insulation to minimize air leakage and control moisture.

To promote construction of energy-saving buildings, Dow said it is launching products including an insulated sheathing made with a high percentage of recycled material.

'We're constantly looking to innovate into that (green building) space, said Scott Young, global portfolio director of energy efficiency with Dow Chemical.

'We're looking to see if we can continue to drive down the cost of construction as well as the overall utility costs for homeowners.'

A move toward environmentally friendly homes is gaining momentum outside the affordable housing sector, too.

The National Association of Home Builders said on its Web site that by the end of this year, more than half its members, who build more than 80 per cent of US homes, will be using so-called green practices.

Lamar Cheatham, president of Ameristyle Construction in Marietta, Georgia, said his company has been including water- and energy-saving features in the higher-end homes it builds for years.

'Everybody is more concerned about (energy efficiency) especially with the rising cost of fuel,' Cheatham said. 'Now water is starting to be a big issue,' with concerns about drought in the US South.

Cheatham said his company's homes feature more efficient heating and air systems, extra insulation in the ceiling and other areas where air can be lost. Toilets with larger drainage throats save water by reducing the possibility of stopping-up, which in turn can cut down on flushing, he said.

Equipping a home with more energy-saving products can drive up costs, Cheatham said. But, he added, 'With the way that energy prices are going right now, it's probably worth it.' Reuters