In the Driftless region of Wisconsin, the state’s southwest corner, the Thornton family is covering new ground in the field of sustainable architecture. Set midway into the side of a hill, with exposed round timbers and a sod roof, their future home has aptly been named “Underhill House,” hearkening back to a character from J.R.R. Tolkien’s Lord of the Rings series.

“Everybody in my family is a big Tolkien fan,” said Denise Thornton, who will be living in the house year-round with her husband, Doug. “The house is designed by Whole Tree Architecture and Construction. It is a design and build firm in La Crosse. They name all the houses they work on, and we were involved in the naming process … Underhill was the name Frodo Baggins used when he went undercover.”

It’s no accident that Denise and Doug were able to work so closely with Whole Tree; their daughter, Della Hansmann, works for the firm and was the primary architect for Underhill. Della studied architecture at the University of Minnesota, after receiving her bachelor’s degree in geography from the University of Wisconsin. Her parents are UW alumni as well.

“We had a unique situation,” Denise said. “We got to talk to our architect more than most people do about what they like and what their dreams are. She knew ours.”

Denise and Doug have two daughters, 24 and 30 years old. Their empty nest and desire to downsize gave them the motivation they needed to put their idea of building a sustainable home into action. Retiring to the Driftless Area eight years ago coincided opportunely with Della’s career decision.

“We always knew we wanted to retire to Wisconsin,” Denise said. “Right after we bought the land, our daughter decided she was going to be an architect. We just made up our minds that when she got done with architecture school and was ready to design her first solo house, we would be that house.”

Heating from solar panels will offset utility use in their home, but much of what makes Underhill environmentally sustainable is the small amount of energy needed to transport materials. Everything has been locally sourced, much of it from the family’s land itself.

“Most of the wood in the house came from our land. No clear cutting, no long distance transport, no high-energy milling,” Denise said, explaining that the tree trunks they repurposed for the house were hand-selected for having diseases, being lightning-struck, or crowding other trees. “For the most part, this was a very low energy process.”

The lime stucco for the house’s exterior came from Manitowoc, the sand from Mount Horeb and straw bales for the insulation came from a neighboring farm. And, relating to a hot topic of discussion in Wisconsin this summer, the house will have no built-in air conditioning unit.

“The house is built into a hill, so that will keep that part of it cooler. And it’s insulated so it won’t be getting hot,” Denise said. “In the summer, the sun is higher in the sky, so we are going to have awnings over the window; it will be shaded. And the transpiration from the grass on the sod roof is a cooling process. It’s designed to have prevailing winds come in from one side and have breezes going through. We are also prepared to do what people used to do and sweat it out. If you turn the air conditioning on it’s only going to make everything else get even hotter.”

Denise and Doug will have a small, wood-burning stove in the main part of the house, and a propane backup. They hope to generate electricity as well as heat from solar power some day.

The couple feels the project is a perfect marriage between high-tech sustainable technologies and reverting back to nature.

“This is more out of the box,” she said. “This is kind of a hybrid between natural building techniques – very elemental things like lime plaster walls, round timbers for the frame, straw insulation and a sod roof – and then mixed together with cutting-edge technology, like windows that are designed to keep it as efficient as possible.”

Although Underhill is their most ambitious endeavor, Denise said all of the family’s homes have had some type of addition or update to make them more sustainable, from a greenhouse to extra insulation. This time around, they wanted “sustainability with a capital S,” which has brought its own set of challenges.

“Inviting all these different techniques is a constant challenge; it’s kind of like feeling your way along. We have to be coming up with solutions on the fly when things don’t quite come together the way they were imagined or planned originally. You have that in any building project but that certainly happens a little more when you are trying to build in a new style,” Denise said. “Nothing is ever square [when using whole trees and branches in construction], and that is a challenge in itself.”

She said, though, that she takes these obstacles in stride, since they are clearing the way for future environmentally-minded homebuilders.

“You learn as you go. But we feel like we are pioneering a message; some of the things we learn in our process will help other people to take it a step further and feel more comfortable. They’ll know what the pitfalls are,” Denise said.

The crew working on the house, Denise says, often comments that the process of building this “treehouse” has taught crewmembers techniques that they will bring to their next project. She says she is happy to be a part of that process, not only to act as a leader in environmental construction, but to help keep Wisconsin’s workers in that field employed.

“I would say we are definitely spending less on materials and more on labor. And I’m ok with that because these are wonderful guys and they have a job while they are building the house,” she said.

The crew has been just the first point of contact when it comes to spreading the word about the techniques employed at Underhill; the Thornton family hopes that once more people see their new home – friends, family and visitors – they too will be inclined to look into a similar project. 

“They are all very intrigued; when people see it, it seems more doable to them,” Denise said. “I think it’s almost got to be word of mouth, someone you know has done it and it came out well, before most people will venture on into familiar territory.

[UW journalism and mass communication professor] Sharon Dunwoody has done research on what makes people change their minds, and essentially found that same thing. Change the minds of people around you and people you know.”

While responses have been mainly positive, Denise said it is easy for people to hold some preconceptions about what life in Underhill house might be like. These hesitant onlookers will have to wait until the project is fully finished to decide if the Thornton’s dream for a liveable, environmentally sustainable home meets the final product. And they may want to revisit the opening line of Tolkien’s first novel:

“Not a nasty, dirty, wet hole, filled with the ends of worms and an oozy smell, nor yet a dry, bare, sandy hole with nothing in it to sit down on or to eat: it was a hobbit-hole, and that means comfort.”