On April 22, the world celebrated the 50th anniversary of Earth Day, an annual event that supports environmental protection. While average citizens can reduce, reuse, and recycle, join a cleanup, or encourage policymakers to act on climate change, builders, designers, and architects in the construction sector have a unique opportunity to alter building processes to reduce carbon footprints and control how the built environment interacts with and impacts the Earth.
In a recent Ann Arbor, Mich.–based project, a local residential building team that specializes in sustainable design, including Michael Klement and Susan Hall of Architectural Resource and Mike and Andrea Mahon of Adaptive Building Solutions, designed and built a high-performance, luxury custom home for a retired, empty-nester couple.
The clients, who advocate for the sustainability movement, initially approached Klement after the wife’s existing health condition required her to have a kidney transplant. Before the procedure, the couple pledged to each other that they were going to build the green home of their dreams when she recovered. They kept that promise and have since dubbed the house “For the Journey.”
The 4,500-square foot home—with an additional 1,750 square feet of conditioned garage and loft storage—includes typical modern features on face value, but its foundation, envelope, and energy-efficient components qualify the home to seek U.S. Green Building Council’s LEED for Homes Platinum Certification.
“Their vision for their dream home was to have a place where the primary function of the home was to be comfortable, with energy efficiency as a key driver” says Mike Mahon, founder and owner of green building company Adaptive Building Solutions. “The house was designed in a way that suits their lifestyle, as they are entering into this next phase of their life.”
Instead of using a traditional Michigan slab with 42-inch footings around the perimeter, the team decided to use a frost-protected, shallow foundation system frequently used in Sweden. Called WarmFörm, the simplified product eliminates the need for extending footings below the local frost line and relies on the home’s insulation to insulate the soil below and prevent it from freezing.
The 4-inch-thick XPS insulated form sits on top of an 18-inch bed of crushed limestone, no footings, and boasts 8 inches of XPS insulation under an 8-inch-thick polished concrete slab, according to Mahon.
“In this case, one design decision solved four things,” says Michael Klement, principal at Architectural Resource. “By deciding to go with the WarmFörm system, we addressed the site’s high water table, the need for solar energy harvesting, the need for a low-cost foundation system, and use that concrete as a way to also generate heat through in-floor heating.”
The in-floor radiant heating was prioritized for the client’s comfort on the polished concrete floors. Tubing was added throughout the entire home and garage, heated by a 4-ton Bosch geothermal system with five vertical wells and loops reaching 285 feet deep.
From the foundation, the walls were framed with 2x6 studs and covered with Huber Engineered Woods’ ZIP sheathing to create an air and vapor control layer. Every seam was taped and caulked to promote an air-tight envelope. Then, Nu-Wool cellulose insulation—an environmentally friendly product made from recycled paper—was blown into the walls. The builder also added 3 ½ inches of Dow XPS foam board insulation and Dow Weathermate housewrap to manage exterior water.
High vaulted ceilings and lots of natural light were additional items on the client’s wish list. The design team responded by developing a contemporary roofline with a mix of flat and shed style profiles.
With soaring ceilings, two layers of structural insulated panels (SIPs), or panels consisting of an insulating foam core sandwiched between two structural facings, were used to construct the roof. The first layer is 12 inches thick and the second outer layer is 6 inches thick. The second layer was added to stop thermal bridging from the 2x12 and LVL structural splines between the SIPs panels below. The entire roof was then covered with a gray TPO synthetic membrane with standing-seam metal accents on the garage facing the road.
Triple-pane windows and exterior doors were selected to complete the envelope and the exterior siding boasts a combination of thin brick, ledger stone, James Hardie fiber cement panels, and lap siding with stained Douglas fir for the soffits.
According to the builder, the final blower door test was 0.5 ACH50, showing minimal natural ventilation and high energy usage control. To provide fresh air for healthy living, the entire home receives a full house air exchange every hour from the RenewAire ERV system that brings in fresh air and expels stale air with about 85% retention of conditioned air temperature.
Energy for the home is generated through a nearby 15-kilowatt ground solar array, oriented to maximize solar gain. Plus, a 60-kilowatt lithium-ion battery backup was installed in the garage to power the entire home for three days, a first for Michigan, according to Mahon. Through the system, the owners produce enough solar power to offset their energy bills and charge two Tesla electric vehicles.
“The clients wisely decided to not add the panels to the roof,” says Klement. “It lets the roof be a roof and lets the panels be accessible in case you need to maintain or clean them. Plus, they didn’t want to impact the aesthetics of the building.”
In addition to energy efficiency, the designers also chose to incorporate several aging-in-place and universal design features for the retired couple.
By selecting the slab-on-grade construction, all of the home’s entrances are barrier-free. The house was designed to allow for wheelchair access on the first floor, with the addition of 36-inch doors for all rooms, and the team installed an elevator pad and framing in the pantry for a future elevator, if needed.
Due to the area’s likelihood of tornadoes, the team wanted to incorporate a safe space where the owners could retreat to since the home was built without a basement. The FEMA-approved tornado shelter was constructed in the master walk-in closet, adjacent to the bedroom for optimal proximity to the owners in case the disaster strikes at night. Built with concrete and a steel, fire-proof door, the space will protect the owners “from anything nature wants to throw at them,” states Mahon.
“This is a very special project,” continues Klement. “We really feel like it is a multiplicity of facets touching on where the market is heading. We are considering this the home of the future, today.”
As for the design details, the contemporary interior includes a neutral color palette with polished concrete floors, dark cabinetry, and white countertops. Custom walnut built-ins, including bookshelves and floating end tables, bring a sense of warmth to the space.
Although it can be difficult to achieve an indoor-outdoor connection in Michigan, where the temperatures can fluctuate dramatically between the summer and winter months, the team incorporated ample windows—high and low—to maximize the natural light inside and make the owners feel they were connected to the surrounding prairie while present in most of the home’s rooms.
“The house in every different way pulls, stretches, and pushes to create the incredible living experience that our clients have asked for,” adds Klement. “They have raved about how the house truly does provide the platform for an inspired life that they can live the journey in.”