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A funny thing happened on the way out of the housing downturn. Before the slump, getting a big builder to even talk about things like solar panels, radiant barrier insulation, and sealed building envelopes was tough. Now, green is rapidly becoming the gold standard in production home building.

KB Home became the latest big builder to get into green in a big way back in mid-July, when it unveiled a prototype entry-level home in its Alamosa community in Lancaster, which is at the north end of Los Angeles County. It goes beyond everything that came before it in two ways: Its roof tiles eat air pollution, and it will be almost totally energy self-sufficient (except for a gas-fired heater and stove).

In a mid-July telephone interview, Steve Ruffner, president of KB's Southern California division, and Bob Kronenfeld, director of marketing, gave Tech Spec a briefing on the first of four prototype homes, which had just been completed and unveiled during a press conference July 13.

“We literally just put the first house up,” said Ruffner, explaining why he could not say how prospective home buyers were reacting to the house. “But the reaction from the media has been really, really interesting.”

For good reason. The prototype house, built to Energy Star standards, also has a 3.96-kilowatt photovoltaic power generation system with lithium-ion battery storage from BYD, a Chinese company that makes batteries not only for energy systems but for cell phones and cars, as well. It allows power generated during nonpeak periods to be stored for when rates are highest. It can store 10 kilowatt-hours of power, more than enough to carry the burden during peak-load periods. On an annual basis, it will generate more power than the house will use (6,800 kilowatt-hours versus the 5,895 kilowatt-hours used by the average household in one year).

The real kicker, however, is on the roof in the form of MonierLifetile, a clay roof tile pioneered by Monier Group in Europe. Into the tile is baked a photo catalyst that reacts with nitrogen oxide, a greenhouse gas that greatly contributes to smog, and converts it to nitrate, which is washed off the roof onto the ground, where it will serve as a fertilizer (though in insufficient quantity to make anything grow quickly). It does so with such efficiency that, over the course of a year, it neutralizes the nitrogen oxide pollution emitted by a car driven for 10,800 miles. Moreover, the catalyst also destroys organic dirt and algae, which also are rendered harmless and washed off with rainwater.

The tiles, which are handled in America by Atlanta-based Boral, are made in Stockton, Calif. The secret is titanium dioxide, according to John Renowden, product manager for the tiles. He also notes that among the other characteristics of the tiles are higher reflectivity and emissivity than comparable tiles, higher thermal mass, and an installation system that leaves an air gap between the tiles and the roof, which acts as an insulating barrier (the KB home also has radiant barrier insulation under the roof deck). Of course, the tiles are significantly more expensive than conventional roofing material such as asphalt shingles, but building codes in most of Southern California mandate the use of tile on new homes. Renowden couldn't provide details on costs, which isn't surprising, since KB's Ruffner said he has not received final pricing from Boral.

When the prototypes turn into models, the price tag will be lowered considerably by state and federal energy efficiency rebates and the waiving of development fees by the city of Lancaster. But here's the kicker: The HERS Index of the KB prototype home is 39. That makes it 61 percent more efficient than a home built to the 2006 International Energy Code.

SMOG BLASTER: KB's prototype home in Lancaster, Calif., features clay roof tiles that will eat air pollution and convert it to fertilizer.

Learn more about markets featured in this article: Los Angeles, CA.