People who move to New Urbanist communities tend to be fans of traditional architecture. But architect Barry Alan Yoakum was drawn to Harbor Town, a 32-year-old enclave just north of downtown Memphis, not by the historical styles of its homes but by its walkability and a requirement that houses have porches overlooking small front yards—features that promote sociability and healthy living.

Barry is a longtime proponent of sustainable architecture, and when he and his wife, Kathy, challenged themselves to build a radically energy-efficient home, a Harbor Town corner lot overlooking the Mississippi River presented the perfect site.

Barry chose to work within the letter of Harbor Town’s design guidelines to create a house rooted in 20th-century modernism, not just for looks but for efficiency. A traditional balloon-frame house, he explains, is a thermal disaster—the studs conduct heat, the myriad joints allow leakage—and hiding raw materials behind finished surfaces is wasteful.

Barry used a construction method that is far more efficient: Factory-made structural insulated panels—non-VOC insulation sandwiched between layers of flakeboard—were transported to the site and affixed to a steel and cross-laminated-timber structure, resulting in a faster build and less need for heating and cooling. The organization of the interior is just as simple: The lower volume, a rectangle perpendicular to the river, contains the main living spaces, a media room/guest room, and a small courtyard that separates the living room from the garage.

“Everybody told me I couldn’t do this in the hot and humid South.”
—Barry Alan Yoakum, architect and resident

Upstairs, a smaller rectangle contains the family’s two bedrooms, a convertible study, and the laundry room. Barry positioned that volume slightly over the northern edge of the lower level, clearing “view sheds” for several of the Yoakums’ inland neighbors while giving the house a jaunty asymmetry—off-kilter but balanced, like an abstract sculpture.

Barry, a partner in Archimania, an 18-person Memphis firm, was determined to minimize the building’s greenhouse gas emissions. Its “very tight” envelope and triple-glazed windows are big energy savers. Windows are sized and positioned to maximize daylight (electric lights are rarely needed before dusk, Barry reports) while reducing heat gain in summer.

A large operable skylight on the tiny third level draws air through the house like a chimney. The need for mechanical heating and cooling is low, and both are mostly provided by 18 geothermal loops that extend 29 feet into the ground. All those features reduce the house’s operational energy needs to well below the norm. The energy it does need is provided by the home’s four solar arrays, two of which feed batteries in a ground-floor mechanical room. (The other two are connected to the local utility.)

During its first year of occupancy, from November 2019 to November 2020, the house produced 13 percent more energy than it used, Barry says. (And that period includes the beginning of the pandemic, when Barry, Kathy, and their now 13-year-old son, Crews, were home most of the time, using far more power than usual.) “We’re like a little utility company,” says Barry.

Barry and his team attempted to minimize not just the amount of energy the house would take to operate but the environmental impact of the energy and materials required to build it in the first place. The first thing they did was avoid grandiosity—at 2,800 square feet, the house is small by the standards of its neighborhood—and unnecessary ornamentation.

Then they chose building materials carefully, using concrete with a fly ash component (a low-carbon alternative to the usual Portland cement) for the foundation and salvaged, recycled steel for the structure. They used software called Tally to weigh material choices based on their embodied carbon—that is, the amount of carbon dioxide released throughout the life cycle of the building and in construction—coming in at about 50 metric tons (11,000 pounds).

Nonetheless, Barry was determined to offset even that small number. He did it by buying offsets (at a total cost of about $390) representing 100 metric tons of carbon conserved by wind turbines off-site. Buying offsets is a tricky business: How do you know that the same wind-generated power hasn’t been used as an offset before? Or that the turbines wouldn’t have been built without your subsidy?

But it was enough for the Yoakum house to be certified as both Zero Energy (meaning 100 percent of the power it uses over the course of a year is provided by new renewable sources) and Zero Carbon (meaning that embodied carbon emissions associated with construction and materials are offset, and energy comes from new, renewable sources) by the International Living Future Institute, the organization that administers the Living Building Challenge—regarded as a gold standard for sustainability measurement. The institute says the home is not only the first house but the first building in the world to receive both its Zero Carbon and Zero Energy certifications.

As for its bold design, Barry was never concerned about what the neighbors would think. In fact, he welcomes their reactions, knowing that a dialogue about the house’s appearance would become a conversation about energy efficiency. “That’s my mission—to get people talking about it,” he says. “This is the future. If we’re going to solve the climate problem, we can’t be looking backward.”

Project Credits:

Architect of Record: Archimania / @archimania

Structural Engineering: Ozer Structural Engineering

Civil Engineering: Powers Hill Design

Landscape Design: Plants + People

Lighting Design: Benya Burnett Consultancy

Cabinetry Design: Warren Construction

Solar Panels and Battery: LightWave Solar

Geothermal and HVAV: Hydro-Temp

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A Radically Efficient Memphis Home Raises the Bar for Sustainability