'Green' has found an unusual mate in the housing market.

While they may seem like an odd couple, prefabricated housing -- in which most of a home's structure is pre-built in a factory then assembled on-site -- is an oddly natural partner for the green movement. Prefab or modular homes can be produced and erected more efficiently, consume less energy and generate less waste than the construction of conventional homes.

The surprising thing is that today's prefab housing is also beautiful, customizable and designed to fit naturally into its surroundings. In the past decade, prefab housing has transformed itself from ugly, concrete, cookie-cutter sub-divisions into elegant, sleek and stylish homes where sustainability is a natural part of the construction process.

The $9 billion prefab industry produces about 140,000 factory-built units annually, according to Bruce Savage, vice president of public affairs for the Manufactured Housing Institute.

Ninety percent of prefab homes are built in factories where skilled craftsman typically work regular nine-to-five shifts assembling pieces of the structure using uniform manufacturing processes on a level surface, rather than a potentially uneven construction site. The pieces are trucked to the site where they are erected on a poured foundation in a fraction of the time it takes to construct a conventional home.

While many people may feel suspicious of the quality and reliability of prefab building strategies, modular homes are constructed according to conventional building codes required by the state, county and municipality where the home will reside. They are not otherwise restricted by building or zoning regulations, says Jeremy Bertrand, executive director of building systems councils for the National Association of Home Builders in Washington, D.C., which now offers its members a voluntary green building standard designed as a tool kit for builders interested in green building practices.

"They meet the same quality standards as a site built home, and they don't look any different," Bertrand says.

Prefab housing manufacturers are subject to state inspector and independent inspection agency review of the manufacturing process during each phase for code compliance and workmanship. During assembly, local building inspectors ensure the structure meets requirements and the finish work is done properly. The modules are produced using modern assembly line techniques, which reflect the input from specialists from various facets of the building trades. The streamlined process results in fewer errors and greater efficiencies. "It's a well designed production system," Bertrand says. P

refab homes also benefit from being assembled in an optimal production environment, says Rebecca Woelke, director of media relations for MK Designs, an Oakland, Calif.-based architectural design firm specializing in sustainable prefab homes. "The factory craftsmen work together in normal shifts in a quality-controlled environment, not up on a ladder or out in the rain," she says. "As a result, the quality is amazing."