Paul and Desirée Brazelton's Minneapolis house was supposed to be the start of something.

The 1935 Tudor near Lake Nokomis was totally retrofitted in 2011 to meet the standards of an extremely efficient German building system that keeps a house warm without a furnace. The Passivhaus system maintains heat with efficient windows and doors and lots of insulation; the Brazeltons added the hot-water heater.

Their house, the first such retrofit of an existing structure in North America, was intended to inspire other middle-income people to build their own Passivhauses. It has inspired others, but their would-be followers are finding the financing harder than keeping a house warm in a Minnesota winter.

"When we first started it, there was very little information about people doing this other than, like, 'Crazy millionaire builds super-awesome house,' " Paul Brazelton said.

The Brazeltons' retrofit was a community event — and they wanted it that way. They blogged about the project and gave public tours once the house started taking shape. As word spread, more than a dozen companies signed on as sponsors, trading supplies and services for publicity.

After a year and a half in the house, they've seen their energy costs drop about 85 percent. There's still a lot of interest from those who dream of an energy-efficient house of their own.

But in the United States, it can be difficult to finance such projects, which cost a lot upfront but save money later. For families following in the Brazeltons' footsteps, there isn't the benefit of widespread sponsorship.

Tim Eian, the architect behind the Brazeltons' retrofit, said houses built to the Passivhaus standard are commonplace in his native Germany and in much of Europe.

"In Germany, you see a lot of high-performance buildings, not just for rich people, but for everybody," he said.

But it's a different story for American homeowners trying to build to this standard, Eian said.

For those who rely on traditional funding mechanisms, he said, it's "virtually impossible to do these projects right now."

Building despite the roadblocks

Tarek and Julie Alkatout are defying the odds, but it hasn't been easy.

Like the Brazeltons, they live in an old house and want to stay in their neighborhood, but they also want a more energy-efficient home that will accommodate their young family. Also like the Brazeltons, they'll be a household of five; their sons Malik and Zayd are 7 and 3, and they're expecting a baby in March.

Inspired by the Brazeltons, they wanted to make their 100-year-old northeast Minneapolis house into a Passivhaus. Soon, though, they found it was cheaper to start from scratch.

They bought the house next door, which had sat empty for three years, and started plans to build something more energy-efficient in its place. The house was recently torn down, and they started digging the footings for the new house this week. They're hoping construction will be complete by summer's end.

The new house won't meet Passivhaus standards, but it'll come close. Like the Brazeltons, the Alkatouts will be able to heat their house with the energy equivalent of three hair dryers.

Julie Alkatout said they knew that financing the house might be challenging, but they didn't anticipate how difficult it would be.

"It's a challenge, and it's a sore point for us, too," Tarek Alkatout said.

An appraiser visited the Brazeltons' house and learned as much about Passivhaus standards as possible. But in the end, there wasn't enough market data to show what the house's energy efficiency would be worth.

The appraisal compared their house with other 100-year-old houses that had recently sold in the neighborhood. When the final estimate came in, it was only 80 percent of the cost of construction — not including architect fees and the cost of buying the land.

"To make up the difference, we had to come up with the cash a different way," Julie Alkatout said.

"It's a little frustrating, because I guess it does make it more risky to build that," she said. "If we did for some reason have to sell, someone would get a really good deal."

Mortgage requirements for all houses have tightened since the recent financial meltdown. Part of what makes financing a Passivhaus even harder is the challenge of showing its benefits on paper, said Ryan Stegora, the professional builder for both the Brazeltons' retrofit and the Alkatouts' new house.

"It's impossible to describe the immediate benefits to owning a Passivhaus," he said. "Until you've spent some time in one, you really can't grasp the difference in comfort."

Stegora said he begins projects by preparing his clients for the cost.

The parts of the renovation that brought the Brazeltons' house to Passivhaus standards — tearing down the original shell, reinsulating, rebuilding and adding new windows and doors — cost about $200,000, Paul Brazelton said. The Alkatouts declined to reveal the cost of their project.

Building a dream house

Even though the Brazelton house is a success story, getting there wasn't easy.

They ran out of money the spring after the project began, even with sponsorships worth tens of thousands of dollars. Paul Brazelton and his father did a lot of the work themselves.

The family moved into the house in August 2012, and they're still finishing pieces of it as they can afford to. Every project comes with a price tag and "a week or two of disaster," Paul Brazelton said.

Still, he and Desirée say there's nothing about the house they'd change, although they plan to add air-conditioning this summer. Because the house is designed to retain heat, it can be a "solar oven" when outside temperatures rise, Paul Brazelton said.

In the winter, though, that's exactly what they want. Even on the coldest days, their heater turns off in the morning, and the house hovers at a toasty 70 degrees all day.

The more the Alkatouts hear about the Brazeltons' home, the more determined they are to make their own dream house.

"Just planning every single inch of this house, at some point you're like, 'OK, I need to start building this house,' " Tarek Alkatout said. " 'I can't wait anymore.' "

Emma Nelson is a University of Minnesota student reporter on assignment for the Star Tribune.