The fourth in a series of interviews with the design, preservation, and construction teams.
To optimize performance and reduce energy consumption, the architects combined strategic interventions at the historic building, such as insulating the existing roof (next image), with high-performance envelope features in the new addition. (Rendering: KieranTimberlake)
As the Weitzman School of Design prepares to open its first new building in more than 50 years—an interdisciplinary hub for research and teaching in the historic heart of Penn’s campus—Weitzman News gathered members of the design and construction teams to talk about the making of Stuart Weitzman Hall. The conversation included Dean and Paley Professor Fritz Steiner (MRP’77, MA’86, PhD’86); Bill Braham (MArch’83, PhD’95), the Andrew Gordon Professor of Architecture and director of the Center for Environmental Building Design; and Surya Prabhakaran (MSD-EBD’20), building performance researcher at KieranTimberlake. All three are Weitzman alums. The former Morgan Building’s history and adaptive reuse will be the subject of an exhibition in early 2026.
Fritz Steiner: Half the energy we use in the United States is from building and building construction, and it’s roughly half of the greenhouse gases produced. So looking at buildings is very important for both our energy future and our climate future. When you preserve a building, you’re preserving all the embodied carbon in that building. That first move is extremely important in not producing or not using more carbon and producing more greenhouse gases. It’s just fundamental to how we think about our future.
Surya Prabhakaran: There’s enormous value in the carbon already embedded in the existing structure. By renovating rather than demolishing, we’re preserving that carbon stock while avoiding all the embodied emissions that would’ve come with new materials.
But preservation as sustainability also means working creatively within the constraints of what exists to achieve modern performance standards—including healthy environments. Given that this serves fine arts students working in studios with toxins and airborne substances from art-making processes, we were challenged to build on existing qualities to improve ventilation and indoor air quality. We prioritized daylight and views—features the existing building provided. These weren’t just nice-to-haves but became fundamental to student wellbeing and the learning experience.
With this diagram, the design team paints a whole-life carbon picture for Weitzman Hall, demonstrating the embedded benefits of building reuse through avoided greenhouse gas emissions, projected accumulation of operational carbon emissions, and the cumulative reductions realized across time. (KieranTimberlake)
Bill Braham: There is a distinction between what we call operational energies—the energies that go into heating, cooling, lighting and so on—and then the embodied energies, the energies used up in getting materials and transporting them and refining them and then actually building them. Depending on the form of construction and depending on how efficient the building is, the proportion between those two can be really different. It used to be that we would say that the embodied energy is worth about 20 years of the operating energy, meaning you’ll use the amount of energy you spent building the building in about 20 years of its life. But as buildings have become more efficient, that means they use less operational energies. So a lot more attention has been going to looking at the energy and the carbon associated with construction.
Fritz Steiner: I would also add, it’s more expensive to preserve a building than build a new one. We probably could have had twice the building for the same cost, in terms of square footage, if it was all new. But we had a commitment to preserving the historic structure from a cultural perspective.
Bill Braham: At the Center for Environmental Building and Design, we did the first sustainability plan for the university in 2005. At the time, Penn had one meter for heating and one meter for cooling for the whole campus, so we had no idea how any individual building was doing. We worked on those programs for many years and then moved into the carbon action plan [link].
When it comes to the history of environmentalism in architecture, we focused initially on energy and then slowly broadened out to include other things. Because when you get into a facilities operation, energy is what you pay for, so it’s always very highly prioritized. So at the beginning this was all about, “How do you make buildings energy efficient?”
“You can’t think about buildings as standalone performing objects—buildings are part of a larger system.”
From a performance perspective, there are three things an institution is trying to optimize: money, energy, and carbon. And you can’t always optimize all three. Weitzman Hall is a pretty good example. You can’t think about buildings as standalone performing objects—buildings are part of a larger system. We call this “scale shifting.” At Weitzman Hall, there were some studies early on that showed if you added in a heat pump-based system and radiant cooling or radiant conditioning, you could actually reduce what we call “site energy consumption” by quite a bit. But that’s not a system that’s common at Penn. And Penn has a huge solar farm, so its electricity is already largely decarbonized. It’s also looking to decarbonize its steam. So, if the steam decarbonized and carbon is your primary interest, then it’s okay if the building uses a little bit more energy—the building is zero carbon.
Fritz Steiner: LEED was developed in the 1990s by the US Green Building Council as an accounting system to measure energy efficiency and environmental responsibility. I’ve worked with the US Green Building Council and its spinoff organization, GBCI [Green Business Certification, Inc], for over 20 years now, and I know Bill has a lot of experience with them. It has its critics, but I’ve found them a very adaptable organization. If you can suggest ways of doing better, they’re very open to that.
Penn students and faculty are rightfully concerned about climate change and energy use. As a result, the university has made a sincere commitment to sustainable design. Penn requires LEED Silver for all of its buildings. Weitzman Hall is expected to earn a high LEED Gold rating, and we still need to see how different things may count or not count.
Bill Braham: Penn, like many other institutions, uses LEED as a way to require a certain level of quality because it’s a well-recognized standard and it requires third-party verification. The program in the 1990s was very different from what it is now. It has constantly been updated to keep up with the innovations in the field so that it’s meaningful. To deliver a GOLD standard building takes work, it’s an investment.
Surya Prabhakaran: Beyond LEED requirements, the historic nature of the building presented many fascinating challenges. One of them was insulating the envelope. It was an obvious strategy for energy performance, but we had extensive discussions about how to preserve the historic masonry while achieving modern performance standards. We initially considered spray foam, which is the go-to solution for durability and performance. Ultimately, we stepped back from insulating the wall, and focused on preserving and even exposing the historic elements. Instead, we improved the roof insulation and replaced all the windows, which provided meaningful energy savings. Extensive HVAC modernization also improved thermal comfort throughout the building. The design team made these interventions deliberately visible, so you can see the old and the new interact with each other. It’s more honest architecturally, and creates adaptability for future needs.
The architects completed studies to maximize useful daylight in the MFA Studios. (KieranTimberlake)
Bill Braham: Did you end up insulating the walls of the original building? A few years ago, we were surprised when an MEBD student used infrared cameras to measure the insulating value of different wall assemblies on campus. The building directly behind the new Weitzman Hall, Towne Building, has 18 to 24-inch-thick brick walls, and no insulation. There was an airspace, but no insulation. The modern thinking is, “That’s terrible!” But it turns out mass actually is pretty effective: It dampens and delays and it has an insulating effect that’s different than the lightweight insulating materials. I assume that showed up in your modeling of the building.
Surya Prabhakaran: Exactly. We realized considerable savings from insulating the existing roof and replacing the windows, whereas insulating the wall would’ve provided maybe an additional 20% reduction in operational energy. But we also have to consider the adverse effects of spray foam on both environmental and human health. The trade-offs painted a clear picture: there are many other strategies that preserve historic characterwhile maintaining energy performance without degrading the building’s cultural value.Bill Braham: It’s also worth noting that the building is well over 100 years old, and look how well it has weathered compared to a lot of modern buildings. I remember when KieranTimberlake first started, they had a partner whose expertise was in preservation, so they were learning from older buildings. They were trying to design buildings that use no caulk because caulk is one of the first things that fails.
Multiple parameters for the thermal envelope of the historic building were evaluated by the design team to understand and isolate strategies with maximum impact on energy use and whole-life carbon. (KieranTimberlake)
Surya Prabhakaran: The one-and-a-half-year program at Penn was foundational for me: The program addressed this essential question: How can we design buildings that truly respond to the climate, environment, and people? We learned to assess and integrate environmental factors like daylighting, carbon footprint, energy performance, and thermal comfort—which is the core of what I do at KieranTimberlake. Beyond technical skills, the program cultivated a research mindset focused on planetary health and building performance. KT operates with the same holistic ethos, so I could immediately start applying the principles I learned in the program to real practice.
Bill Braham: Surya is very much the model graduate. She’s found herself in the kind of place that we imagine EBD graduates thriving—a firm in which they have a separate performance or research group, but it is very much part of the culture of the firm. There’s a lot for our students to learn after they graduate, but the orientation of the EBD program is very much, “How do you learn all these tools?” We can’t teach you all the tools, but we can help you learn how to ask the right questions, how to frame the question in an architectural way.
It’s not hard to be innovative in the environmental sphere in architecture these days. But the minute you innovate, you’re doing something for which there isn’t a tool that can tell you if it’s working or not. So the research mindset that Surya describes is everything.
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