Tim and Muffi Abrahamson haven’t decided on a color scheme yet for the new house they’re building for themselves on Carter Avenue, but that hardly matters. Even before they buy a single gallon of paint, they’ve already got the greenest house in the neighborhood.
The Abrahamsons—with a little help from their good friend, local architect Lucas Alm—are the designers and builders of the first net zero house in St. Anthony Park. The house is still several months from completion, but if all goes according to plan, the Abrahamson house will create as much energy as it consumes, through an ingenious trifecta of good design, solar panels and super-thick insulation.
Huge south-facing windows will capture passive solar heat in winter, with the added bonus of offering year-round great views of their treestudded backyard. Then there is what Muffi calls (in the blog she’s writing about their project) “some serious insulation.” The 14-inch thick walls will be wrapped in several inches of the same expanded polystyrene (EPS) insulation that will be packed under the concrete foundational slab, with dense-packed cellulose used in the ceiling.
The final support in the balancing act that’s going to keep the house comfortable even in the worst of Minnesota’s weather is the array of solar panels that the Abrahamsons are installing on the south-facing roof of their detached garage.
The Abrahamsons will remain very much “on the grid,” essentially turning their house into a mini power-production facility for Xcel Energy. On sunny summer days the solar panels will allow them to produce more energy than they use.
“In summer, we’ll produce energy and sell it [through energy credits] to Xcel,” Tim says. “In winter, we’ll consume more than we produce.”
For the Abrahamsons, the new house represents the dream of a lifetime. When they moved to St. Anthony Park in the late 1980s, the couple bought a house with an extra lot, even then cherishing the plan that someday they might build their own house. They had always been interested in sustainable, environmentally friendly housing, and Tim’s decades of experience as the head of his own construction firm gave them confidence in their ability to master the technical details. Now on the cusp of their 60s, with their two children grown, the Abrahamsons knew it was finally time to make their move.
“I’m glad we waited,” Tim says. “We would have built a nice house [earlier], but solar technology has improved so much.”
They’ve also mastered the lessons of an earlier generation of green housing design. “In the 1970s, we wanted to build ‘tight’ houses, but now we know that we [also] need to provide air exchange” to keep fresh air flowing to the living spaces, he says.
The couple describes the planning process for their new house as “incredibly fun” (Muffi) and “the project of a lifetime” (Tim). “We always wanted to live in a house we designed together,” Muffi says. “We have similar tastes.”
For an occasional corrective suggestion, they called on the expertise of fellow St. Anthony Park resident, Lucas Alm, founder of Alm Design Studio. “Lucas can look at our design and prevent our mistakes,” Tim says.
The net zero project offers distinct building challenges even to an experienced contractor like Tim. “We’ve incorporated green products and techniques in other projects,” he says. “But I’m mostly a remodeling contractor.”
Many of the subcontractors working on the new house have worked with Tim before, he says, “but they can’t believe how much insulation we’re using this time. There are a lot of surprises, because this is a unique way to build.”
One of their building solutions came in response to the need to strengthen the wall bearing the giant array of solar windows on the south face of the house. How do you create enough window area to be effective on sunny days without running the risk that the wall blows in when the weather turns stormy? With the memory of straight-line winds that had downed dozens of trees in the neighborhood several years ago fresh in their minds, they knew that structural support was crucial.
“We created sheer walls with a 3.5-inch-by-9-foot-high solid piece of laminated chip board with steel anchors that ran down to the footings,” Tim says. A 20-inch-wide beam connects the wood and steel supports.
Although they describe themselves as using “early adopter technology,” the Abrahamsons have what might strike some as a surprising affinity for traditional design. The energy solutions of their new house may be radical, but the “look” of the house will not be.
“We want it to fit into the character of the neighborhood,” says Muffi. Their two-story, twobedroom house will feature an open floor plan on the first floor living area and lots of open space upstairs that can later be turned into additional bedrooms. A front porch and an exterior made of traditional lap-siding and cedar shakes will help the house blend in with its neighbors. The most eye-catching exterior feature may be the steel roof.
A steel roof may be unusual, but it will also pay off in the long run, Tim notes, comparing its 50- to 100- year life expectancy to the 20- to 35-year life of a conventional shingle roof.
And that raises a principle they’ve returned to often. “Building this house is more expensive than the conventional building process,” says Tim, “but I think people will have to realize that it will be more sustainable in the long run.”
Their roof may still be here in 100 years, but, of course, the Abrahamsons themselves will not. No matter. In their minds, they’re building not just a comfortable house but a better world.
“We hope the house will be an example to show that [net zero] construction can be done in an urban environment,” says Tim. “In order to move society forward, we need to be able to build houses that are both super-insulated and don’t ignore the position of the sun.”
The Abrahamsons think net zero houses like theirs will be “the norm by 2040.”
“We feel [building the house] is the right thing to do,” Tim says. “It’s a moral imperative. Our children and grandchildren have to live in this world.”
For now, though, he concedes, “this project is unusual.”
“You need the right client,” he adds with a laugh, “and I have the right client.”
Judy Woodward is a reference librarian at the Roseville Library and a regular contributor to the Park Bugle.