SAN DIEGO, California - Environmentally-friendly buildings have evolved from hippy habitats to office towers and shopping centres, becoming a far more commonplace presence in city skylines and communities throughout the United States, as well as overseas.Call it the "Al Gore Factor" or the "George Bush Effect", but there are several reasons behind the renewed interest in the energy-efficient, low-impact buildings -- ranging from dramatic footage of melting icecaps to rising oil and gas prices, to the United States' dependency on energy sources from unstable regions of the world. There is now little disagreement that the U.S. needs to curb its appetite for fossil fuels in the years to come.

"It's definitely a growing trend. We have more work than we can handle," said Carolina Caroline E. Fluhrer, an engineer at the Rocky Mountain Institute (RMI), based in Boulder, Colorado.

RMI, a consulting and environmental design firm, has observed the change in perceptions firsthand as their roster of clients grows to include corporate titans such as Wal-Mart and even the White House. "People are starting to realise that green building is just good business," Fluher said.

She noted that there is empirical data verifying the overall benefits of sustainable building. "It's no longer just hearsay -- there's hard evidence you do realise significant energy and water savings," she said.

The soft benefits of natural lighting and improved ventilation are also gaining credence among advocates who cite reduced absenteeism and better health for building occupants.

Much of that evidence has been gathered by the U.S. Department of Energy in case studies involving the past two decades of green-build projects. According to the DOE, high-performance buildings that incorporate green design principles are worth the initial upfront investment.

Although up to 10 percent more expensive during initial the phase of construction, green buildings are cost-effective in the long run, cutting energy expenses up to 50 percent over the lifetime of the building. The potential for energy savings is even greater for residential properties, providing powerful incentives for owners and developers to consider green options.

For the average wage earner managing a home mortgage, energy conservation isn't a partisan issue. Nationwide, the average home uses 1,400 dollars of energy and emits 4.0 metric tonnes of carbon dioxide per year, accounting for up to 20 percent of greenhouse gases annually.

Recent studies indicate that 60 percent of the U.S. public consider themselves to be environmentalists, and when surveyed 40 percent of homeowners state they plan on incorporating green elements in home improvement projects, running the gamut from using low VOC (volatile organic compounds) emitting paints to retrofitting their homes with solar panels.

So far, government agencies have refrained from defining what an eco-friendly or green building is. That task has fallen to the U.S. Green Building Council (USGBC), a non-profit organisation founded in 1993 that has grown to include 12,000 members.

Over time, the USGBC developed the Leadership in Energy and Environmental Design (LEED), a widely accepted standard for green building certification. LEED-certified buildings incorporate three if not all of these elements -- fuel efficiency, water conservation, proper ventilation, and resource conservation and site management.

"People are looking for ways to turn the clock back on global warming. Green buildings are a demonstrable aspect of that, especially as gas prices continue to go up," said Ashley Katz, a spokesperson for the USGBC.

According to Katz, as of 2007, just 2 percent of homes were green. The value of this marketplace is approximately 7.8 billion dollars. However, growth is expected in coming years. Given forecasts of the overall housing trends, this segment of the housing market is expected to increase to 10 percent by 2010.

"They're really popping up all over the place," said Katz. Grand Rapids, Michigan, for example, has one of the highest numbers of certified projects in the country. Currently, there are 400 LEED certified homes with 10,000 more in the pipeline.

In California, LEED principles are in the process of being codified, and the construction of state government-owned buildings must adhere to green guidelines. Seventy-two cities nationwide are following suit.

Awareness of the global impact of green homes reached a tipping point in 2007 when the normally staid National Association of Homebuilders gushed on their web site that sustainable building is "exploding", and that more than half of their members -- who build 80 percent of the homes in the U.S. -- will be incorporating green elements in upcoming projects.

Having said that, perhaps the greenest buildings of all will be the projects not under construction. According to the U.S. Census, housing starts for single family homes fell 24 percent over the past year and will continue to decline in coming months, slowing the pace of urban sprawl and reducing the rate of carbon emissions as the transport of labour and materials to and from work sites slows to a crawl.

In fact, while the housing market is slow, green building is one segment of the industry where demand is outstripping supply as homeowners and builders, whether driven by sentiment or pragmatism, seek earth-friendly alternatives to traditional housing construction.

© 2008 Inter Press Service