Charles Darwin might have found an interesting research subject in the Burke family's Goleta home, which has evolved over the last 47 years as the family has changed.

Chuck and Harriet Burke purchased the five-bedroom tract house in 1962 as a place to raise their five rambunctious kids. As the children grew, the Burkes added a 425-square-foot family room in 1967 and a swimming pool in 1971.

The house became a post-child-rearing retreat for the couple in the 1980s and '90s. The kitchen was updated with granite counters and a slate floor, and two bedrooms were combined to make a grand master suite.

Then, following Chuck's death in 2006, the house evolved once again into an environmentally sensitive, solar-powered, intergenerational home for Harriet Burke and her oldest daughter, Kathy Scheidemen, 52.

The latest improvements -- completed last year in seven months for $300,000 -- include solar water heating, operable skylights, woods from sustainably managed forests, drought-tolerant landscaping, doors from century-old homes and a mirror salvaged from the Santa Barbara Biltmore.

"I'm really proud that we did it," said Burke, whose only regret is that her husband, who was involved in the early planning, did not live to see the remodel completed.

The idea to split the house into two living areas so Scheidemen could move in came about several years ago, as Burke increasingly needed help taking care of Chuck, who had emphysema and used oxygen tanks.

Though the house had bedrooms to spare, Scheidemen could not see herself moving into one of them. "That would be like being 12 again," she said.

The first idea was to add a second story for Scheidemen, who also became part owner of the house in the new living arrangement. But the cost of building up would be exorbitant, at around $500,000, and the new space meager -- around 210 square feet -- when required setbacks were figured in.

Working with Santa Barbara architect Paul Poirier, the mother-daughter duo decided to split the house in two sections, with Burke's space encompassing the original bedroom areas, and Sheidemen's taking the original living room and family room -- with a side entrance and the kitchen between the two.

This would give the two women opportunities to spend time together but also shut doors to the common areas for private time.

From the beginning, they wanted to make the project as environmentally responsible as possible. Through one of her siblings, Scheidemen was familiar with Dennis Allen, whose company, Allen Associates, is a large and respected green builder in Santa Barbara.

"We knew from the very beginning we wanted Dennis Allen, if he had time for us," said Scheidemen, who manages a research lab at UC Santa Barbara and is on a sustainability committee on campus.

At first, the mother and daughter figured on spending $200,000 for the remodel and "not a penny more," Scheidemen recalled. She and Burke listed everything they wanted in the project, including:

* Diversion of 98% of demolition and building waste from the landfill through reuse and recycling.

* Use of as much pre-owned and salvaged materials as possible.

* All energy for the home generated on-site (photovoltaics and solar water heating for the house and the pool).

* Materials obtained for the remodel from a 350-mile radius, whenever possible.

* Wood certified by the Forest Stewardship Council.