Buy five modules. Drop them on a West Town lot. Fit them together like Lego bricks and call it home.

Someday, green living might be as easy as Michael and Kathy Caisley made it look when they installed in one day what is considered the first prefabricated, modular home in Chicago. But the carefully choreographed, one-day event required extensive preparation.

"It's been over a year and a half in the planning," says Kathy Caisley. "If this were just any old house and it took this long, I would be annoyed. But we knew we were doing something different, out of the box, against the grain."

The resulting 2,000-square-foot home meets the highest levels of sustainable construction as defined by the U.S. Green Building Council's Leadership in Energy & Environmental Design. The couple hired Helios Design + Build, a licensed general contractor in Chicago, to build it.

Financing posed the biggest obstacle, Kathy says, because the banking industry views prefabricated homes differently than traditionally built homes. "We are still battling this myth that prefab is some sort of substandard construction type," says Jeffrey Sommers of Square Root Architecture + Design in Chicago, the architect who designed the modules. Also, banks seem reluctant to loan money for new projects in the aftermath of the mortgage crisis, he says.

Sommers and the Caisleys say they decided to prove that a prefabricated, modular, energy efficient house can cost the same as a traditional, "stick-built" house. They saved thousands of dollars in interest on their construction loan, Kathy says, because it took less time to build. Constructing it in a climate-controlled factory eliminates weather delays. Also, they expect utilities to be less than half those of a traditional house of the same size.

Further advantages of modular prefabrication include owning a designer house at a lower cost, Sommers says. "Everyone has an inherent hesitancy to work with architects, thinking they are only for high-end clients," he says. "We are trying to do some of the design work ahead of time so we can lower our fees but give clients something unique without re-creating the wheel every time."

Sommers says efficiency starts with the home's thermal envelope, which includes windows, doors, roofing and insulation. Without a tight envelope, everything else is "relatively meaningless," he says.

Mechanical systems come next. He says he chose a ductless HVAC system to eliminate heat loss, reduce the potential for mold and allergens, and allow room-by-room temperature control.

Solar thermal panels heat the Caisleys' water. They cost about $13,000, but tax credits and rebates cut that in half, according to Sommers. "It's a no-brainer," he says. "It's a good feeling to know the sun is heating all that water rather than using gas or electricity."

Still, the Caisleys say they missed their goal of spending $200 per square foot or less. "But that's including everything - the Miele appliances, the hardwood floors and the European cabinetry," Kathy says. "I wouldn't want to scare people off because I think you could definitely still have a great house and reduce some of those variable costs."

Chicago green builders say these types of projects spark awareness and more business. "It makes me feel good they are implementing and testing theoretical things," says Tony Slade, owner of highly rated DesignFirst Builders in Itasca [Ill.]. "I can start to implement some of the things they are doing."

He says his clients are open to green technologies, but they want to see a relatively quick return on their investment. "If you tell them it will pay for itself in 12 years because you will save a lot of energy, they are very interested in it," he says. "If it will pay for itself in 30 years, they say 'No way.'"

Pete Pryor, owner of highly rated Pryor Construction in Chicago, gets similar feedback. "It's a balancing act," he says. "People are trying really hard to do things right but keep it within something they can afford."

Still, projects like the Caisleys generate buzz. "It gets people asking more and willing to spend more," he says.