Ed Binkley has designed many costly mansions in his day, including a concept home for Tiger Woods. Now he's turning his attention to homes that are small but comfortable, affordable and green.

As the McMansion boom goes bust, "the focus is moving toward high-density, single-family houses on small lots," said Binkley, an architect who recently left BSB Design in Orlando, Fla., to launch his own company, Ed Binkley Design.

The plans and sketches on the drawing board in his home office show cottages and duplexes in a variety of architectural styles. The designs in his Shelter Series range from 600 square feet to a little more than 900. Each features flexible spaces that can be used for cooking, eating, living and sleeping.

Four units could fit onto a 70-by-120-foot lot, he said.

This fall, he plans to build his first model home, in a partnership with Kimmel Lumber, in Venice, Fla. He estimates the cost will be a modest $50 per square foot, or about $24,000 for the smallest design.

He also is meeting with builders and developers, with an eye to erecting models in Sarasota and Sanford.

"I picture them incorporating parking for a Smart car and Ikea-type fixtures," he said.

Binkley envisions his compact houses in a variety of settings, including on urban in-fill sites and suburban cul-de-sacs. The units also could serve as graduate-student housing on college campuses, backyard guest houses or resort-area cabins, he said. Or as first homes for newlyweds, retirement homes for empty-nesters or relief housing for victims of natural disasters such as hurricanes.

"I've long been interested in smaller, affordable housing," said Binkley, who won a national competition with a Habitat for Humanity house he designed in Yonkers, N.Y., in 1998.

"How small can a space be, and still be flexible and livable? It has a lot to do with volume and light. I've created sloped ceilings to add volume, and big windows for light."

He admits the lack of storage space might be a turn-off to some people: "But the less storage, the less stuff. We all have too much stuff."

Created from pre-cut and numbered SIPs (structural insulated panels) and pre-colored fiber-cement Hardie siding, the houses could be assembled rapidly on-site, producing little waste. And the panelized system could easily be expanded in 8-foot increments.

The houses would be energy-efficient "because they're so tight," he said.

The 8-inch-thick roof panels would have an R-36 heat-conductivity value, compared with the industry requirement of R-19 (the higher the value, the better the insulation).

Combine that with insulated walls and low-E windows, and you've got a "sealed system," he said.

The small size would eliminate the need for much air-conditioning duct work. Most electrical conduits would be external. And solar or point-of-service hot water could be an option.

For more details, go to Binkley's www.edbinkleydesign.com site.

For homes like these to be built, "We need more flexibility with zoning laws. Governments need to release some regulations to make building quicker and easier," said Binkley. "Then all I'd need is the nerve to just do it."