When most people think of a “green building,” they think about using less energy for electricity and heating—not less energy to build it in the first place. But by then, it’s too late, says John Ochsendorf, Class of 1942 Professor of Architecture and Professor of Civil and Environmental Engineering. While tremendous strides have been made in the last decade to reduce the energy buildings use on a daily basis, he says, comparatively little effort has been placed on the amount of consumed resources—or “embodied carbon”—the building itself represents. “It’s like taking a Hummer and putting a solar panel on top to power the windshield wiper and saying, look, that’s a green car,” he says.

And yet, the future of our planet’s resources may depend on radically changing the way we construct buildings. “The bottom line is we built cities one way in the 20th century,” says Ochsendorf, who speaks with a relaxed twang that harkens to his rural West Virginian upbringing, “and we simply cannot afford to build that way in the 21st century.”

Specifically, architecture in the past century relied almost exclusively on concrete and steel, two materials that are very energy-intensive to produce. “In the 20th century we thought of energy as cheap, so it became easy to make bad designs, building glass boxes all over the world and then burning fossil fuels to make them comfortable,” says Ochsendorf. “But those glass boxes aren’t efficient from an embodied energy or an operational energy standpoint.”

Ochsendorf has made it his mission to make that change. Along with several graduate students and practicing architects and engineers, Ochsendorf helped build two buildings—one in South Africa, and one in England—that each used just 40 kilograms per square meter of embodied carbon dioxide, 10% of the energy consumed in constructing a typical building. They did it in part by choosing more optimal structural forms—for example, curving vaults instead of flat slabs. But a large part of the energy savings came from utilizing low-carbon materials (in this case, locally made bricks) to bear the load.

For someone so forward thinking, Ochsendorf finds much of his inspiration in studying the past, investigating construction techniques such as Renaissance masonry, Gothic cathedrals, and Incan bridges to learn their secrets. “There are better solutions out there, in particular local solutions all over the world that were developed over the centuries by people for their climates,” he says, absently stacking model clay bricks on his desk while he talks.

In order to truly change how buildings are made, Ochsendorf believes, we must integrate architects and engineers more closely in the design process; together, they can make early-stage, crucial energy-saving decisions. Ochsendorf has long been interested in green building—he proposed a thesis on sustainable practices in civil engineering while at Cambridge University 20 years ago—but it wasn’t until coming to MIT in 2002 that he made it the focus of his work, inspired in part by the multidisciplinary nature of the Institute. “No one discipline is going to allow us to create low-energy cities in the future,” he says. “MIT is one of the few universities in the world that has a really strong architecture program and a really strong program in civil engineering—and not only that but the two departments are physically linked [with the former in Building 1, and the latter next door in Building 5].”

Now, he and colleagues in both departments are linking the fields even more closely: revamping the curriculum for increased collaboration among architecture and engineering students, and developing a software platform to exchange rapid feedback between disciplines on strategies to reduce energy cost. “These projects are really only possible with an integrated team where you are thinking about structure, and materials, and geometry, and operating energy all at once.”