In Washington, D.C., thousands of visitors stream through the “Green House” exhibit every week at the National Building Museum. It's on track to become the museum's most popular exhibit. Meanwhile, millions of Americans watched recently as This Old House transformed a 1926 Austin bungalow into an eco-friendly home.

It's official: Green has gone mainstream. As This Old House producer Deborah Hood says, people no longer need view green as experimental or expensive. “We're learning that green is basically just good planning and smart building.” And green remodelers echo that sentiment. They're as likely to use words such as “high-performance” when talking about their green work, so interwoven are the concepts.

Green remodeling, loosely defined, refers to building for energy efficiency, water conservation, and healthier indoor air quality; using products and materials that are sustainable; and reusing or recycling materials rather than dumping more waste into a landfill.

Different corners of the country play up different aspects of that definition, though. One of the basic principles of green building is to tailor strategy by region. So, for example, in California, reusing and recycling is key, since there's no more room in landfills. In New Mexico, water conservation is a critical focus. And the farther north you go, the more insulation factors in.

Consumers are driving the growing green trend for a number of reasons, among them the need to rein in soaring energy costs, the threat of global warming, and mounting health concerns — particularly for the one-in-13 children with asthma, a condition aggravated by poor indoor air quality.

In some parts of the country, legislation is spurring the need for energy-efficient buildings, as well. In Boulder, Colo., for example, residents will soon be charged a carbon tax based on how much electricity they use, prompting many to make updates to old, drafty homes. In Montgomery County, Md., new legislation requires public and some private construction to be LEED-certified.

Some state governments are also moving toward green reform. In California, the Air Resources Board is considering standards that would ban toxic substances such as formaldehyde, which is present in cabinetry, pressed wood products, glues, and adhesives. (The state already has Title 24, establishing energy-efficiency standards for construction.) And in Massachusetts, legislation passed last summer bans certain demolition debris from landfills.

By enacting legislation, green practices are being moved from the fringe to the mainstream, state by state. As electricity demands strain power plants and as landfills fill up, that trend will likely spread across the country. And remodelers who haven't yet come onboard may soon be forced to do so.

BETTER BUILDING “Green has absolutely exploded,” says David Johnston, a Denver-based green-building consultant and author of Green Remodeling: Changing the World One Room at a Time. “There's a market demand for it on all levels, both building and remodeling.”

But are remodelers ready? “Consumers are interested way beyond the industry's ability to respond, especially the remodeling industry,” Johnston says. “They're about five years ahead of us, which is why there's sort of a scramble among remodelers to catch up.”