While 2020 was a rough year for most people, Matthew Vetting and Tracee Vetting-Wolf came out ahead.
At least their Rochester home did, in the amount of energy it produced compared to what the couple and their teenage son consumed.
The home rooftop has a 9.8-kilowatt solar system to generate electricity that was $21,000 after a $9,000 rebate. A heat-pump cooling and heating system with a wall-mounted air handler provides heat in the winter and cool air in the summer. It produces warm air from the outside condenser in temperatures as low as -15, Vetting said. A hybrid water heater extracts ambient warmth from the air to keep water warm. That, in turn, cools the basement.
“It basically turns into an air conditioner when it’s operating,” he said.
Those technologies add to the home’s efficiency, but they aren’t the core of it.
What allows the home to generate more power than it uses is the design of the house itself. The walls are double-studded walls 9.5 inches apart filled with spray foam. The triple-paned windows and doors, made by Milwaukee-based WASCO windows, have double seals. Most of the windows face south, with an overhang designed to invite in sunlight when the sun is low in the sky in the winter and shade the home from direct sunlight in the summer.
These features are what’s known as "passive design" — meaning the design of the house itself is an energy-efficient system.
Before moving into the medical field, Vetting-Wolf earned a degree in architecture. She recalls studying passive design elements during that time.
“To me, they seemed so obvious and so right,” she said.
While some architecture is designed for aesthetic beauty, Vetting-Wolf said she saw beauty in the function of the design.
“Another definition of beauty is how well you can build something to be functional in its environment,” she said.
The single-point heat-pump heater has been enough to warm their 1,800-square-foot, two-story home even during the polar vortex, along with some natural help.
“Usually when it gets down to -30, the next day is a sunny day,” Vetting said. The house worked the way it was designed to.”
Around the winter solstice, the sun pours into the main floor of the home a couple feet short of the far-north wall. That helps warm the concrete floor. An open interior lets the heat from the sun-bathed floor and the wall-mounted air handler move freely through the home. By June, the window angles and an overhang keep the sun from hitting the floor, which helps cool the house in the summer.
To learn more about the design, and follow updates on the home, visit the couple's blog at vettingwolfhomestead.com.
Vetting-Wolf came up with design concepts for the house. She had a former classmate and licensed architect draw up plans.
Rochester's Derby Builders constructed the home in 2018, and won a national efficiency award for a small, custom build. By that and other measures, the house is a success.
It has a Home Energy Rating System (known as the HERS index) score of 33. To put that into perspective, a typical new build has a score of 100. An older house with less energy efficiencies would have a 130. The home is 67% more energy efficient than a typical new home. Factor in the solar capability, and the score goes to 3.
The total cost of the home was $450,000. It sits on a plot of about 26 acres on the south edge of Rochester. The couple grow vegetables and raise bees on the land, and are working their way toward a self-sufficient homestead.
Three main reasons inspired the couple to build a net-zero house: One was financial, after living in a 1920s Craftsman house in Ossining, N.Y. It required about 1,000 gallons of oil per year to heat the home. When heating oil spiked to $3.80 per gallon, the couple decided to eventually build a home that wouldn’t put their finances at the whim of energy markets.
Another was scientific curiosity.
“I like to try things out, get results, and see if the results match the hypothesis,” Vetting said.
But the main reason was consideration for the future.
“We were just interested in doing our part to help the planet,” he said.
The home hit two building code snags as it was being completed. One of the second-floor windows was too low and was slightly redesigned.
Second, state code requires homes to be able to maintain a minimum temperature of 68 degrees. Inspectors were dubious the heat pump and passive efficiency was enough to maintain that temperature through a Minnesota winter. In order to pass inspection, the couple installed wall-mounted electric heaters in the bedrooms they rarely use.
“It was frustrating, but we’re OK with it now,” Vetting said.
Vetting-Wolf occasionally runs the one in her bedroom office for comfort while she’s working from home.
She said she hopes builders and others see how design can make a big difference in energy use.
"We wanted to inspire people to think differently about beauty," she said.
Through the project, architects and a local builder learned more about passive design — and that's a beautiful thing, she said.