Experts Give Their Wisdom On Today’s Best Sustainable Building Practices

With climate change knocking at the door, architects look for ways to reduce the carbon emitted when houses are built or renovated
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Rooftop Solar panels power a Miami beach residence by architect Max Strang.Kris Tamburello

Earlier this year, a modernist mansion overlooking Biscayne Bay, marketed as the only solar-powered house in Miami Beach, sold for $15.25 million. The 112 photovoltaic panels on its roof feed batteries that, by some estimates, can keep the 5,500-square-foot residence running for weeks or even months.

Does that mean the house is green? As with so many things, definitions matter. Building a house—a process that can include pouring concrete, importing marble, and forging steel—requires vast amounts of energy. Producing that energy releases tons of CO2 into the atmosphere, exacerbating the “greenhouse-gas effect” that causes climate change. In fact, buildings are responsible for about 40 percent of the world’s greenhouse-gas emissions. And much of that isn’t from operational energy—the electricity to power lights and air-conditioning—but from energy used to construct the buildings in the first place. That’s known as embodied energy.

Architect Michael Green worked to minimize embodied energy when updating a 1912 North Vancouver house.

“There’s no denying that homes of this size and complexity contain lots of embodied energy,” says architect Max Strang, who designed the Miami Beach residence. He hopes that the solar panels will produce enough excess energy to pay off some of that debt over time. “To not try to offset embodied energy would just be sitting idly by,” Strang says.

But that repayment could take 100 years or more. Today, Strang and his peers are grappling with the reality that the world doesn’t have that kind of time. “If we’re going to hold warming to 1.5 degrees Celsius, which is the goal of the Paris agreement—or anything close to that—we’re going to have to deal with embodied energy right now,” says Vancouver architect Michael Green.

So when Green renovated a 1912 craftsman-style house in North Vancouver for a couple with grown children, the did whatever he could to minimize the energy expended. “The first green thing we did was to not tear down the house. Reusing what you’ve got is a big part of sustainability,” he says. And when he enlarged the back of the house, he chose wood as the main structural material. Unlike steel and concrete, wood is created “using the power of the sun,” he says. “I’d rather use photosynthesis than photovoltaics,” he adds, meaning that reducing embodied energy now, by choosing wood, is better than trying to produce more energy in the future. (Particularly because it takes a lot of energy just to manufacture PV panels.)

SoLo House, a prototype by Perkins&Will, follows 
passive house principles.


Andrew Latreille

On Whidbey island in Washington, architecture firm Miller Hull used reclaimed materials and a 
modest footprint to minimize environmental impact.


LEED, the leading “green” building-certification system, puts little weight on embodied energy, which is why architects are turning to apps like Tally (from the Philadelphia architecture firm KieranTimberlake) to add up the energy that goes into their buildings. Even with an app, computing a building’s embodied energy isn’t easy. But common sense goes a long way. The less you build, and the less concrete and steel you use, the better. And the less shipping you have to do, the better. Thomas Bercy and Calvin Chen of the Austin architecture firm BERCY CHEN STUDIO tend to use stone rather than concrete whenever possible—it requires no energy to produce and, because they work with local quarries, little energy to transport to the building site. When designing a private house on Whidbey Island, outside Seattle, local architecture firm Miller Hull used reclaimed materials (some from another home in the clients’ family) wherever it could.

Of course, operational energy still matters. Bercy Chen’s houses often have rooftop solar hot-water heaters (essentially glass-top tanks exposed to the sun), which are affordable and practically foolproof, along with other energy-saving systems. HouseZero, Snøhetta’s experimental transformation of a Harvard University building into a laboratory for energy-use research, employs a glass “solar chimney” to ventilate its basement. Back on Whidbey Island, Miller Hull placed a photo-voltaic array in a meadow not far from the house. “The takeaway,” says Chris Hellstern, a sustainability director at the firm, “is that energy-efficient homes are possible.”

A Texas house by BERCY CHEN STUDIO employs local limestone in lieu of concrete.

Some architects go further, adhering to a set of guidelines for reducing houses’ operational-energy needs to a bare minimum. So-called Passive Houses rely on natural phenomena—sunlight, shading, cross ventilation—rather than on active heating, cooling, and lighting. Lots of insulation and triple-glazed windows keep heat inside in winter and outside in summer. Perkins&Will’s SoLo House, an alpine prototype in the Soo Valley north of Whistler, in British Columbia, follows some of those principles, meeting the Passive House Institute’s PHI Low Energy Building criteria despite its large windows, which are strategically placed and sized to maximize solar gain when closed and promote cross ventilation when open.

Almost any kind of dwelling can become a Passive House. In Brooklyn, GRT Architects is renovating a pair of 1840s Greek Revival houses that, when completed to Passive House standards, will require only 10 percent as much energy to operate as conventional houses. One challenge is that the required insulation takes up lots of space, but, GRT cofounder Tal Schori says, “we’ve made the thickened walls a distinct feature of the design—a quilted surface that has rounded edges reaching out toward doors and windows.” For homeowners who don’t want to reinvent the wheel, a California company called Plant Prefab is offering a variety of factory-built Passive Houses.

As for the embodied-energy problem, there are some positive signs. Membership in the Carbon Leadership Forum, an organization for architects and engineers exploring ways to reduce the embodied energy in buildings, has risen from fewer than 400 to more than 6,500 in just over two years. And local chapters are springing up all over the country. Kate Simonen, the founder of the forum, says, “Architects are finally seeing the urgency and starting to act.” —Fred A. Bernstein