SANTA CLARITA, Calif.—The KB Home development here looks like any other middle-class subdivision in Southern California—rows of stucco houses with tiled roofs and two-car garages—except for the sticker on the entryway of one of its showcase units.

The sticker displays the average monthly cost to heat and cool the home and run the appliances: $119, compared with $252 for a standard-built home of similar size. If an owner adds solar panels, the monthly bill would drop to near zero.

Buried inside the extra-thick walls of these homes are layers of high-density fiberglass insulation flanked by rigid foam boards taped together at the seams to forge a thermal barrier. Every crevice, duct and electrical outlet is coated with a special sealant to prevent leakage.

“We’ve turned the home into an airtight fortress,” says Jacob Atalla, KB Home’s vice president for sustainability. All of the nearly 2,300 houses the company built in California last year were equipped with similar energy-saving features. Some had even more. The company presold all of them, at premiums of 1.5% to 3.8% above the price of similar homes without those features.

Read the full story. (Wall Street Journal)