It’s not enough to design super-efficient new buildings. To reach zero-net carbon, architects have to improve performance in existing buildings, and make the most of the embodied carbon we’ve already spent on them.

By KATIE GERFEN
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Given that we’re on target to double the current square footage of building stock globally by 2060, it would be criminal to ignore existing building inventory as an opportunity for reuse. Quinn Evans principal emeritus and 2018 AIA president Carl Elefante, FAIA, and senior associate Richard JP Renaud, AIA, explain why renovation and adaptive reuse—staples for their firm—are critical to achieving the necessary carbon benchmarks.

You have said that “the greenest building is the one that is already built.” Why are the renovation and adaptive reuse of existing buildings so important to achieving zero net?
Carl Elefante, FAIA: We have a carbon burden that already exists in the built environment. As designers, we’re thinking about the future, we’re thinking about new buildings. The challenge is to not increase the current carbon burden, which means new buildings have to be much, much more energy-efficient, contributing much less carbon, ultimately contributing zero. But that does nothing to reduce the existing carbon burden. We’re not going to get to zero without drawing down from where we are today. To do that, we have to address the performance of existing buildings.

How should architects and developers approach the existing building stock that they should be considering for renovation?
Elefante: “The mountains and the carpet” is Ed Mazria’s description—the “mountain” of modern, tall, dense buildings surrounded by a “carpet” of midcentury and earlier low-density buildings—and it describes an important duality that exists when you start to look at the carbon needs. The types of policies and programs needed to address getting to zero carbon with the large downtown buildings is very different from the challenge of the dispersed buildings in the carpet.

What are some of the challenges?
Elefante: The concentration of dense, large buildings downtown has a relative handful of owners. To get at their carbon footprint, you’re dealing with a few stakeholders. The projects are large enough to potentially fund all of the analytical work of energy modeling and life cycle assessment that needs to be done to reach performance goals. In the carpet, you have many thousands more owners, down to the ones with a single property. The scale is so small that it’s very hard to say to an individual homeowner, “Spend money doing modeling, life cycle assessments, and optimizing alternative design scenarios.” It tends to require a more prescriptive approach: “Here are things that you can do to adapt your residence or small-scale commercial building: Insulate your roof and walls, upgrade your mechanical systems to all electric, etc.”

In large-scale renovation or reuse projects, where are the opportunities with embodied carbon?
Richard Renaud, AIA: With the mountain buildings, the envelope is a good target. Many of the curtain walls in early modern buildings had very little concern for thermal performance—keeping the view and light was their primary objective. Operationally, how can we improve the curtain wall? And when is it too far gone to be able to be improved? This all comes back to improving performance and minimizing the future use of carbon. The curtain wall was made out of aluminum and glass, two materials that use a lot of carbon to make them. What can we do to save that carbon? Not replacing it becomes very important. The Professional Plaza Building [shown above, in Detroit, which Quinn Evans renovated] was a nice midcentury building that actually had a thermally insulated curtain wall. The owner came to us and said: “From a monetary basis, I want to retain this curtain wall. What can we do to improve its performance?” In his eyes, it’s money; in our eyes, it’s carbon. The owner wanted to save money, he wanted to make the building more efficient. He wanted to reuse as many materials as possible in its redevelopment, which inherently is what we intend to do, too.

Are there ways for architects to get owners thinking more about carbon?
Renaud: The mountain is actually a lot easier, because the owners are going to come to architects. The problem, as Carl said, is with the “carpet.” You have thousands of owners, and most are not going to hire an architect.

Do we write off the carpet too quickly as not worth saving?
Renaud: Yes. If you come in [to a carpet building] and you have four walls and a roof, even in poor condition, if you can save anything, it’s a plus. We’ve got to stop looking at it only as saving money, and start saying: “How much carbon do we have here, and how is reuse going to save it?”

Elefante: We can’t do this without systemic change. I constantly find myself reminded of the founding of AIA 160 years ago. What was happening then was the adoption of what we now call Building and Life Safety Codes. What we’re faced with today is really similar. Back then, the systemic change was recognizing that it was more important to have all buildings fireproof so that we didn’t have a disaster every time somebody dropped a candle. We need systemic change here as well, and the basis for the change is there. City after city is beginning to develop plans for carbon reduction. There is no way to get to the reductions that are needed without addressing carbon in the building stock—both operational and embodied carbon. Even if you find no value in an existing building other than to keep its basic structure, that saves so much embodied carbon. How do we really start to think about our buildings as carbon sinks, as ways to sequester carbon?

Is sequestering the carbon that is already in the built environment critical to achieving zero?
Elefante: Yes. We just can’t throw these buildings out. We’ve got to work with the buildings that we have and continue to make them valuable. If we’re looking for quick reductions in carbon, the place that we have to look first is embodied carbon. If you start with scenarios like renovating existing buildings, then you are instantly saving carbon. This market change is happening very quickly. From my own perspective of being an official old guy and having been around for the rise of sustainability and green building, there’s an awful lot of people around that say, “Architects really missed the boat on the green building switch, so others took it on.” This is going to happen even more quickly, and it’s imperative that architects wake up and make this transition from being carbon polluters to being carbon sequester-ers. It will be either the saving or the demise of our profession.