High Design / High Performance

Memphis architect Barry Yoakum’s Harbor Town home, Civitas, is a groundbreaking glimpse into the future.

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“Great architecture comes from great constraints,” says Barry Yoakum, FAIA.

Many young artists believe that absolute freedom is vital to maximizing creativity. But as the lead partner at archimania, Yoakum understands that the blank slate doesn’t exist in the real world. “The way we in this firm practice, we embrace those constraints,” he says. “Because the minute we understand the constraints, we know we can actually do a great job.”

Yoakum learned the art of constraints early. In 1974, when he entered the University of Tennessee’s acclaimed architecture program, the world was feeling the effects of the first oil shock, when an embargo tripled the price of oil in a matter of months. Yoakum, then an 18-year-old who described himself as a “gear head,” began to think in new ways about energy. “I had a muscle car, and I knew what it did immediately.”

The architecture community found itself scrambling to adapt to a new world of scarcer energy. “They had to start teaching differently,” says Yoakum. “My immediate education became professors starting to figure out that we had to do more passive approaches. So my career has always been focused on doing more with less.”

He sees parallels in the current situation, when, after a long period of inexpensive fossil fuels, the Russian invasion of Ukraine has once again sent the cost of energy skyrocketing. “What’s happened in the last few months — the good side of it — is that people are asking, ‘Why are we dependent [on fossil fuels]? What do we do to make ourselves independent?’ We make ourselves dependent, but we don’t have to, if we want to control it.”

Climates, Large and Small

It’s no secret that Planet Earth is getting hotter, and the reason is carbon dioxide. Every time we burn natural gas for warmth, coal for electricity generation, and gasoline for transportation, we dump waste carbon into the air. It’s a big planet, so increasing the concentration of carbon dioxide in the atmosphere from 280 parts per million, where it was at the beginning of the Industrial Revolution, to 420 ppm, where it is now, may not seem like a big deal, but it is. Carbon dioxide traps heat, and more of it is in the atmosphere now than in the past 14 million years. If we want to continue to live on a planet that will allow such essential endeavors as growing food, we have to stop burning fossil fuels.

Building construction and operation produces 39 percent of the world’s carbon emissions, according to the United Nations Environmental Programme. Architects like Yoakum know that’s not sustainable. He and his colleagues have been working for years to make the buildings they design cleaner and more energy efficient.

In 2016, Yoakum’s professional interests merged with a new chapter of his personal life when he got married. “We met at church. I had another house. Kathy lived in Collierville with an eight-year-old who is now my son, too.”

At the time, Yoakum lived in a Harbor Town house he designed called Sky Cottage, but the couple started planning to build a new home for themselves on a 6,600-square-foot lot he owned on Mud Island. In 2017, the couple attended the American Institute of Architects National Convention in New York, where they learned about the AIA 2030 Challenge, a program whose goal is to create buildings that would emit zero carbon by the end of this decade. For Yoakum, given what he understood about the urgency of the climate crisis, that was too late. He and his wife agreed to design their new abode to meet the demanding standard. “We were trying to do something a decade early,” he says.

What excited Yoakum about the project was that it presented him with the most rigorous set of constraints he had encountered in his long career — and since the result was to be his home, he would have to live with the consequences of either success or failure. “It’s one of the most strenuous standards, that merges high design with high performance,” says Yoakum. “The goal was to keep it within a reasonable budget, so we could learn from it.”

In 2021, Civitas was 107 percent positive. These numbers are even more remarkable considering that they were achieved during a pandemic when the family was home, using energy almost all the time. The International Living Future Institute declared Civitas the first zero-energy, zero-carbon, single-family home in the world.

He knew he would need to call on all of his experience and creativity, and inspiration came from unlikely sources. “I had been reading a great book [Spacesuit: Fashioning Apollo by Nicholas de Monchaux] about the 21 layers it took to make the Apollo space suit. We were doing research for FedEx, trying to reinvent micro-climates. If you think about a house, it’s a micro-climate. If you can do that in a suit well enough to keep somebody from dying in space, surely you can do it decently for a house.”

Another inspiration was Roger Bannister. For years, conventional wisdom held that it was physically impossible for a human being to run a mile in under four minutes. But in 1954, Bannister, then a 25-year-old medical student, finally did it. Forty-six days later, another runner beat Bannister’s record, proving that the four-minute barrier had always been more psychological than physical. “If we’re serious about decarbonizing the built environment, it can be done and you can do it,” says Yoakum. “It’s about breaking a barrier of thinking.”

Getting to Zero

To figure out how to attain “net zero,” the team at archimania scoured the available research. Yoakum became convinced that it would be possible to exceed the goal, and achieve a “net positive,” where the home produced more energy than it consumed. “You’ve got to have a really good envelope, you’ve got to produce your own energy at some level, and you really have to have geothermal. That’s three ingredients to get to net positive.”

“A really good envelope” means as little air exchange between the inside and outside as possible. This proved to be especially important for a house sited on the banks of the Mississippi River. When he consulted with outside energy efficiency experts, Yoakum says he heard that, while constructing a net-zero home might be feasible somewhere with low humidity like Colorado, or places in Northern California where you could take advantage of coastal breezes, in the sultry South it seemed far-fetched.

Yoakum and his team turned to the field of materials science to find a solution. “We brought things that had not been done here before, like structural insulated panels, which are very green, very sustainable, and a very tight envelope,” he says. “So there’s a lot of new materials.”

Instead of a typical “balloon structure,” in which a basic framework is covered with non-load-bearing panels, the team chose repurposed steel beams to provide basic support and used a material called Cross Laminated Timber (CLT) to form the floors and ceilings. CLT utilizes wood planks glued together to form panels, which are then layered on top of each other to add thickness. Each additional layer is situated perpendicular to the last, and sealed with a laminate. “Cross laminating builds strength in both directions,” says Yoakum. “It is a structural panel. It’s not a finish.”

The CLT panels are easy to work with and, since they’re made of wood, they don’t add to the home’s carbon footprint. The archimania team were so impressed with CLT they immediately began to use it in other projects, such as The Grove at Germantown Performing Arts Center.

For much of the exterior, Yoakum chose coated aluminum panels. Aluminum can be recycled, but the process is very energy intensive, which worked against the carbon-free goal. But Yoakum says the white material helps reflect the bright summer sun, and its durability sealed the deal. “These panels are shielding this thing for life,” he says. “Even if the coat starts to wear off after 50 years, it’s aluminum under there, so it will continue to be white at some level. We think it’ll age really lovely.”

Sun King

The key to Yoakum’s second factor — producing your own energy — is solar power. Fifty-nine solar panels line the home’s multi-layered roof. Most of them charge the 9.8-kilowatt battery array that powers the house. Two solar arrays feed the electricity they produce back into the grid, which TVA buys through the Distributed Power Production program. Yoakum says that while they have a contract to sell energy to TVA, “they disbanded it right after we finished our house.”

He thinks that was a big mistake. “We need TVA back in the game, and I think TVA needs us as a collective.”

The third factor that proved critical in reaching net zero was a geothermal heat pump. The relatively new technology takes advantage of the fact that temperatures remain stable underground. Loops of pipes are sunk 29 feet into the ground and filled with a mixture of water and antifreeze, which circulate constantly. In the winter, it’s warmer underground than above ground, so the system harvests heat from below. In the summer, it’s cooler underground, so the earth acts as a massive heat sink.

The three stories are connected with both a staircase and an unusual glass elevator system that relies on compressed air rather than cables to move up and down. Yoakum says, “It’s kind of like the Jetsons!”

The heat pump maintaining the temperature inside the home saves a lot of energy, but it doesn’t solve the problem of the dreaded Memphis humidity. “You have to face the fact that we’re going to have high humidity, and we have to change that,” says Yoakum. “You can’t just depend on ocean breezes.”

To reduce the indoor moisture load, the team focused on any home’s biggest source of humidity — the bathroom. They decided to isolate the shower, bath, and toilet area from the rest of the envelope and vent the extra humid air directly to the exterior.

With these and other technologies, such as radiant floor heating and a system that funnels rainwater from the roof to create what Yoakum calls “a big refrigerator on top of the house,” the team thought they had cracked the zero-carbon problem.

But would it all work as planned? Yoakum acknowledges, “We were a little concerned for the year we were going through it. Are we going to make it? We have data and everything, but some of it’s still projections. You can’t determine exactly how much sunshine you get.”

Civitas

Yoakum sketched the initial plan for the three-story, 2,700-square-foot home freehand. The first floor would be wide and long, with massive windows. “I like to think cinematically,” he says, with widescreen views of the river.

To prevent the heating summer sun from penetrating the glass frontage, the windows are set back behind a wide, cantilevered ledge that shades the interior spaces “like a baseball cap.” The lower floor’s interior is usually visible from the street, but a series of aluminum scrims can be quickly wheeled into place when the occupants desire more privacy. The front door leads into a long, thin room that serves as kitchen, dining room, and sometimes a home office. “If you’re going to put a kitchen at your front door, it’s got to look not exactly like a kitchen,” he says.

“If we’re serious about decarbonizing the built environment, it can be done and you can do it. It’s about breaking a barrier of thinking.” — Barry Yoakum

The appliances are integrated seamlessly into the walls — and naturally, they are all electric. “We don’t burn any carbon in this house.”

Yoakum says the lower floor’s design was meant to blur the line between interior and exterior, and be a space that welcomes visitors. That hospitable spirit is reflected in the house’s name, Civitas, which means “community” in Latin. “I’ve always enjoyed creating things that create dialogue.”

The second floor is more private, containing the home’s bedrooms and bathrooms, with smaller windows strategically placed to take advantage of the river views. All the second-floor rooms are connected by a long hallway. “It’s a little wider than a normal hall, maybe, but this is a 62-foot-long gallery.”

One skylight on the western end of the hall is strategically placed so that a shaft of light illuminates a sculpture at noon on the summer solstice.

The third-floor loft serves as a gym and meditation room. The three stories are connected with both a staircase and an unusual glass elevator system that relies on compressed air rather than cables to move up and down. Yoakum says, “It’s kind of like the Jetsons!”

Putting It to the Test

Civitas was ready in late 2019. As soon as the family moved in, they immediately began collecting data from sensors placed throughout the house. While other energy-efficiency standards only prescribe what materials and techniques to use in a building, the AIA 2030 award is performance-based — meaning, you have to prove it works in the real world.

“We tried to pretty much live like a normal family,” says Yoakum. “We’ve got a son who is a teenager now — he’s 14. So we three were living in a new environment, and we had a year to see how it works. We’d been doing all kinds of calculations and software programming, trying to be reasonable, but we weren’t trying to dial it down too much. We were trying to determine how you become good stewards of the house, but we didn’t say, okay, we’re only going to take one-minute showers.”

Today, after almost three years of habitation, it’s clear that Civitas does work. “There’s a lot of other little subtleties,” says Yoakum, “but our desire was to hit AIA 2030 a full decade early — we wanted to do it in 2020. We did. We occupied the house November 1, 2019. A year later we were 113 percent positive, which means we made 13 percent more energy than we used.”

The second year, Yoakum bought a Tesla electric vehicle, which he charges using the home’s solar panels. In 2021, Civitas was 107 percent positive. These numbers are even more remarkable considering that they were achieved during a pandemic when the family was home, using energy almost all the time. The International Living Future Institute declared Civitas the first zero-energy, zero-carbon, single-family home in the world.

Archimania immediately used the lessons learned from Civitas to renovate their South Cooper offices, which the ILFI also certifies as a net-zero-energy, net-zero-carbon building. The home has been winning awards and attracting attention — and new clients — from all over the country. “Go call every architect in the U.S. and see who’s done this,” says Yoakum. The answer is, we got there first and second. And I think the reason is the four-minute mile. Nobody believes you can do this, and if you do, they believe it’s outrageously expensive. But we did it, and proved it does not have to be outrageously expensive.”

Editor’s Note: While is it true that many homes have been designed to produce more energy than they use (“net-zero energy”), or whose construction techniques were tailored to produce no greenhouse gas emissions (“net-zero carbon’) what is historic about Civitas is that it is the first single-family home to be certified as both net-zero energy and net-zero carbon by the International Future Living Institute (IFLI) based on an audit of data collected from its first 12 months of occupation.