Amy and Ben Bonham are Baby Boomers who admire Frank Lloyd Wright's architecture and are keenly aware of their impact on the environment, right down to the number of kilowatt hours they use.

The couple, who live in Moon, foresee the day when living on one floor will make sense but still want to be able to walk to a vibrant, urban neighborhood. Their goal of building economical, ergonomic and energy-efficient housing prompted them to create a development called E Lane (www.elane.biz or 412-264-6682) at 826 Washington Ave., in Carnegie.

So far, two of nine planned condominiums have been built. The upgraded model, which was finished two weeks ago, lists for $219,900 and the other unit starts at $204,900. Both have two bedrooms, two bathrooms, a courtyard and 1,100 square feet of living space.

The upgraded model has porcelain tile in the entryway and bamboo floors. There's cork flooring in the kitchen, beech countertops, a multi-colored slate backsplash and IKEA cabinets. A tubular skylight installed in the kitchen ceiling has an inner mirror that bounces daylight into the room; a diffuser inside spreads the light and keeps out the heat.

You can leave the windows open when you are away. The Andersen awning-style windows have a rain sensor that alerts them to close if precipitation starts.

Tucked in a closet off the kitchen is an "energy smart" hot-water heater that senses patterns of usage. An attached garage with glass-block windows accommodates one full-size car, one compact car and still has room for storage shelves along one wall.

The house's exterior walls are built from structural insulated panels that contain extruded polystyrene that is 51/2 inches thick. The SIP roof is 101/4 inches thick and its insulation has an R factor of 43. Owners can expect to pay about $480 a year for heating and cooling, the Bonhams said.

With all that insulation, "you don't have a lot of heat loss" and the interior space is especially quiet, said Mr. Bonham, who is co-owner with his wife of Bonham Asset Management. The couple own 30 rental properties throughout Allegheny County.

They say the condos' ideal buyers would be first-time home buyers, couples who are downsizing or single parents with children. People who have disabilities may be interested because the units are ADA-friendly, Mr. Bonham said, adding that the towel bars in the showers are actually grab bars.

An open house will be held today from 1 to 4 p.m. The property is open at that time every Sunday and by appointment. The listing agent is Coral L. Stengel of Howard Hanna Real Estate Services (412-833-3600).

The Bonhams bought the property in February 2005 for $225,000 and the vacant land is assessed at $24,000 (www2.county.allegheny.pa.us). The condos are four blocks from Carnegie's five-block business district, which includes a restored Carnegie Library, art galleries, several restaurants, a cafe and an annual blues festival in late summer. Carnegie (www.carnegieborough.com) is in the Carlynton School District ( www.carlynton.k12.pa.us.)

Thirteen properties have sold on Washington Avenue in the past four years for prices ranging from $32,5000 in November 2006 to $225,000 in January 2006 (www.realstats.net).

Outside, there's landscaping with native plants such as Pennsylvania wild grasses, mountain laurel, teaberry shrubs, chestnut and witch hazel trees and Pennsylvania white pines. The trees and shrubs were planted around a retention pond that will capture water runoff from roofs and driveways and can handle a 100-year flood. A newly planted orchard includes raspberry bushes and flowering apple, quince, plum and pear trees.

"If we take the natural approach to everything, it really makes more economic sense," said Mr. Bonham.