Sustainability in Practice
John Ochsendorf in Conversation with Guy Nordenson
John Ochsendorf. Photo © Holcim Foundation, click to enlarge.
John Ochsendorf (pictured) is a professor at the Massachusetts Institute of Technology (MIT) and a speaker at RECORD’s Sustainability in Practice event at the school this month. His research focuses on the mechanics and behavior of historical structures. He is the recent recipient, along with Juliana Berglund-Brown, of an approximately $1 million, three-year grant from the Environmental Protection Agency to measure and mitigate carbon emissions in construction. The grant will fund research to advance understanding of structural steel products at the end of a building’s life and assess the impacts of reusing steel in new buildings. Here he talks with fellow structural engineer Guy Nordenson.
Nordenson: I want to get your reaction about the recent restoration of Notre Dame. From these older structures and their alteration, we can discuss the impact of material choices and decisions to demolish or reuse.
Ochsendorf: I personally am very happy with the decision to restore, not only in-kind with materials but also in technique. Many of the timbers were hewn by hand, so that you can see the axe marks, and it was an opportunity to nourish those crafts, to make sure we still know how to shape oak timbers. I do think that people who visit expect to see something that represents authenticity. If you were to repair that roof in steel or carbon fiber or some other material today, we could have built it faster and cheaper, and the photos for most of the tourists would have looked the same. You could have put slate on the outside. But does it matter that those are oak-timber frames built in a traditional way from locally harvested oak trees? I think the answer is yes. Ultimately, any structure represents our values and it’s a cultural act, and rebuilding it in stone and wood using traditional techniques showed that we still have an ability to do hard things. I think there’s something quite poetic about the act of rebuilding it by traditional means.
Something we’ve been discussing together for a while are two Japanese structures: the Ise Shrine, which is rebuilt every two decades, and the Horyu-ji Buddhist temple, that is patched and repaired and includes some hinoki wood that has been there for over 1,000 years. Can you reflect on that as an example or a lesson for us in the context of sustainability and material use?
Both of those examples hold really deep meaning for me. The renewal of Ise roughly every 20 years for more than 1,000 years really captures the imagination, because it says immediately that buildings are impermanent and we must plan that. If it were left alone for 100 or 200 years, it would probably be okay. But by ritualizing its renewal every 20 years, you say this is impermanent and we’re going to address that. Acknowledging directly and then completely renewing Ise is very similar to me to the Inca grass bridge that I’ve been studying for about 30 years. That’s the oldest bridge in the Americas. Most people haven’t heard of it. It’s been there for probably 700 years, and it’s renewed every year from locally available grass. I think we have a lot to learn from it, because the reality is, most of our buildings today are being torn down before the end of their life. We thought the Kingdome in Seattle was an anomaly, but, in fact, American stadiums, as a recent MIT thesis has shown, are torn down, on average, about every 30 years. These stadiums are not at the end of their life. We’re landfilling pretty good material, or we melt a steel beam down and make a new steel beam and say, “Look how green this is.” But the lessons from traditional architecture, from these two Japanese examples, are that materials have much more value than that. This question of complete replacement versus maintenance or repair also gets at deep values. We all know we do not maintain our infrastructure or our buildings well enough, and we can see examples of that all around us. Questions about the lifetime of any structure are absolutely critical, and more often than not we don’t acknowledge them. It’s something that’s missing in our education right now, of both engineers and architects. We don’t acknowledge time scales of buildings in a way that we should.
I recently participated in a book commemorating the 60th anniversary of New York’s landmarks law. It was interesting to think about the building techniques that were prevalent in the early days of high-rise construction. The tile arches and, of course, your specialty, the Guastavino vaults. There’s a history of invention, of craftsmanship, that we treasure while we restore. How do we think about that in the context of reducing carbon emissions, embodied carbon, and so on?
In many ways, the building codes have codified the proper ways of building, the two true ways of building. And by that I mean steel or concrete. We have highly detailed building codes that are not too dissimilar from where they were 100 years ago, but now they’re really enshrined as the only true ways to build, that we can certify, and that we can defend in a courtroom if lawyers are involved. Did you follow the code or not? The astonishing thing about this is that we effectively threw away 5,000 years of human development around the culture of building. I could give you many examples, of which a Guastavino-tile staircase is but one. There are earthen walls that are stories high all over the world that have been maintained for centuries. You have farmhouses in France that are 700 years old. You have tall buildings in Yemen made of earthen construction that is local, that requires a certain amount of maintenance and renewal. For me, it really is about our progress ideology: Are we at the pinnacle of all time and is there a one true way to build, or are there methods of building that may be seen as anachronistic today but have great value and great lessons for us in terms of local material, labor implications, craft implications, and maintenance? Faster, cheaper building—as industrialized as possible, with materials from wherever you can get them—comes with dramatic carbon implications that deserve to be questioned.
I’m thinking about the Union Carbide building that was recently replaced here in New York for a new tower. Some of the claims that are made for new buildings—that they provide natural ventilation or energy savings—aren’t always realized. But there isn’t a great deal of research that I’m aware of, about whether these claims are actually sustained in practice.
The 52-story Union Carbide Building, designed by SOM, was completed in 1960 and demolished in 2021. Photo © Archive Photos / Getty Images
I think of every new building as a research project, as an experiment that was done. The Union Carbide example is one that is really motivating a lot of our students right now, because so many of the steel sections that went into that building could be reused in new structures and could be mined as a resource by the architectural and engineering communities. But, because of the great inertia of the systems, of the demolition contractors’ taking it down and then selling it pennies on the ton for scrap, we need a more radical intervention to say this material has value, let’s mine it and use it and give it as feedstock for something else. We’re just going to take 300 of those beams that came down and store them and then renew them with a bit of labor. I think we’re at a fascinating time for the built environment, because the issues have never been more critical. And I find our educational systems to be woefully ill-equipped for what we face in the decades ahead. We really have a postwar, new-build approach. Most of the education focuses on new buildings. In the case of structural engineers, a graduating structural engineer in the U.S. has never encountered a brick arch or a timber covered bridge and doesn’t have any real ability to prove that those work, or even just the cultural sensitivity that they may have value. We have historic systems being torn down. It’s on us as educators. I’m very frustrated with what we— including me—are teaching.
Your point about reusing steel sections from a building that has been taken apart—that ought to be part of the code. There should be some regulation, just as there’s regulation for new buildings, of what to do with the remains of a deconstructed one.
In terms of circularity, we’re at a very exciting moment where more and more designers can now specify reused or upcycled materials. We just got a grant to help develop reused steel and are working with the American Institute of Steel Construction (AISC) to create code guidelines, so that if you wanted to reuse a piece of steel from an older building, a steel section, you would be able to do it inside a framework. We need more radical actions to find better ways to operate our buildings. The students inspire me because they are often ahead of us, and circularity is central to a lot of student research and designs right now in schools of architecture. For me, what it comes down to right now is that our profession of structural engineering is in real need of embracing more design and more history, more culture, more values, so that we can continue to bring unexpected solutions to projects. That’s the challenge that we face in the coming decades: how do we help our field continue to bring new ideas to the table and not to be frozen, with a single set of solutions? The beauty of steel and concrete is that you can do essentially anything. By being in a dialogue with the past, whether it’s an Incan bridge or a Japanese temple, it says there are different ways of achieving longevity in structures. If you go to the Oyster Bar that’s supporting the main concourse of Grand Central Terminal in New York, those are doubly curved thin shells that are unreinforced; they’re about 4 inches thick; they carry millions of travelers every day. The building code today says you cannot do that. So my fascination with historical methods of construction and structure is from pure intellectual interest. It’s not out of nostalgia. There are fascinating ways to build that we are not teaching and the building code is not embracing, and the coming decades are going to require us to question that.
