With factory-based construction, architects can construct buildings by combining prefabricated parts like Lego pieces. (Image: Audrey Shtecinjo / Stocksy)

Episode 14: Factory-based Construction

Thanks to innovations in design, materials, and machinery — and a green wave taking over the industry — factory-based construction could be an idea whose time has finally come.


“City of the Future” is a podcast that explores ideas and innovations that could transform cities. In this episode, hosts Eric Jaffe and Vanessa Quirk discuss how factory-based construction are changing the way cities are built with Northeastern University architecture professor Ivan Rupnik, architect and author Susan Jones, and Sidewalk Labs Director of Building Innovations Karim Khalifa and Associate Director of Building Innovations Lily Huang.

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Eric Jaffe: In 1967, Montreal hosted the greatest show on earth.

Radio Voice: A billion dollar spectacle to celebrate the country’s centenary of confederation: Expo 67, the greatest show on earth! On a man-made site in the middle of the St. Lawrence River, an estimated 50 million will have visited the largest world fair ever.

Vanessa Quirk: People from across the world, even the Queen of England, traveled to the French-Canadian city to catch a glimpse of the different pavilions — each with their own vision of what the future might hold.

Radio Voice: In the vastness of it all, the giants face each other: the Russia pavilion across the river from the dome of America.

Eric Jaffe: There was the American pavilion, a huge geodesic dome designed by Buckminster Fuller.

Vanessa Quirk: There was the Bell Telephone pavilion, where visitors could try out the Picturephone, a newfangled device that let you see the person you were calling.

Eric Jaffe: And then there was a building called Habitat 67, the future of urban housing.

Radio Voice: Will we all be living in places like Habitat? Where precast concrete blocks appear to balance crazily, just to make sure everyone has a room with a view?

Vanessa Quirk: Habitat 67 was a precarious, intricate system of building blocks stacked in such a way that each unit would get its own garden — its own suburban-style pocket of fresh air and nature.

Eric Jaffe: Habitat 67 was designed by a young Israeli-Canadian architect named Moshe Safdie. In fact, it had been his thesis project when he was at McGill University. And it was Safdie’s thesis advisor who picked the Expo lineup, including Habitat.

Vanessa Quirk: But while Habitat 67’s crazy concrete blocks intrigued the public, the project also kicked up its fair share of controversy.

Image of a building made of stacked concrete blocks
Habitat 67 was built for Expo 67 in Montreal using precast concrete blocks. (Image: Sylvain Pastor / Wikimedia Commons)

Eric Jaffe: So what happened?

Vanessa Quirk: Safdie’s thesis project had put forth a plan where all the apartments would be made in a factory and assembled on-site. It wasn’t a new idea, exactly — Henry Ford had revolutionized the auto industry with assembly lines. In theory, making building parts in a factory, just like making cars in a factory, should mean big cost and time savings too.

Eric Jaffe: But Safdie’s plans soon came up against some cold, hard realities.

Vanessa Quirk: The original construction contract was for $10 million, but the whole thing ended up costing more than twice that amount.

Eric Jaffe: While there were many reasons things didn’t go as planned, for Safdie, the main reason came down to the material.

Vanessa Quirk: Concrete was chosen for Habitat 67 because it was strong and fireproof.

Eric Jaffe: But it was also heavy. Each unit weighed about 80 tons, which required the building team to purchase expensive, heavy-duty cranes. Writing in 1967, Safdie himself admitted: “The ideal material is yet to be developed.”

Vanessa Quirk: In other words, the project was just too ahead of its time.

Eric Jaffe: But today, building materials and other manufacturing advances are finally ready to change the way we build our cities.

Vanessa Quirk: Welcome to City of the Future, a podcast from Sidewalk Labs. Each episode, we explore the ideas and innovations that could transform cities.

Eric Jaffe: We’re your hosts. I’m Eric Jaffe.

Vanessa Quirk: And I’m Vanessa Quirk.

Eric Jaffe: In this episode, we’re exploring an idea that will finally allow our buildings to catch up to the grand visions of the past.

Vanessa Quirk: Factory-based construction.

Ivan Rupnik: Habitat 67 was a very impactful project, but it also followed a very problematic approach that architects consistently use: instead of looking at the material culture and the supply chains and logistics, we tend to reimagine things as if a new industry will automatically appear and support our ideas.

Eric Jaffe: That’s Ivan Rupnik. He’s an architect and professor at Northeastern University who’s spent a lot of time researching and writing about the history of factory-based construction, sometimes called offsite construction.

Vanessa Quirk: When it comes to that history, most architecture buffs think of the ’20s and ’30s and the Bauhaus movement in Europe.

Eric Jaffe: But Ivan told us that those European architects were inspired by even earlier projects in the U.S.

Ivan Rupnik: Walter Gropius literally brought those German magazine articles on American precedents back to the U.S. — so even the “Bauhaus, avant-garde” architects were really interested in a much more incremental change to the building culture, and we just didn’t have the sensibility to understand it.

Vanessa Quirk: Despite America having some of the earliest examples of prefabricated construction, we just didn’t have the sensibility or the willingness to make a whole building culture around it.

Eric Jaffe: But Europe did. And once we got to the Cold War era, that didn’t sit well with the U.S. anymore.

Ivan Rupnik: The CIA was actually spying on the Soviet Union because there were so many units built in Moscow that there was a belief those numbers couldn’t be true. There was a real embarrassment on the side of the U.S. that, despite fairly large growth in America’s suburbs in the ’40s and ’50s, the Soviet Union and others were just beating the pants off of the country in terms of housing production — good or bad, high quality or not, just on a purely numbers game.

Vanessa Quirk: It’s almost like housing was another sort of arms race!

Eric Jaffe: Exactly. So the U.S. Department of Housing and Urban Development, HUD, came up with a plan to beat the Soviets at their own prefabrication game.

Vanessa Quirk: They called it: Operation Breakthrough.

Ivan Rupnik: The idea was to build units as demonstrations. They would not necessarily prove that the system was entirely optimal yet, but they would at least introduce these into the ecology. New technologies and new construction systems would sort of be forced onto what were seen as unwilling builders or contractors.

Vanessa Quirk: So did these unwilling builders and contractors take up these new fabrication technologies?

Eric Jaffe: Yeah, how did that go?

Ivan Rupnik: It’s literally officially been called a failure by Congress.

Vanessa Quirk: Oh, geez.

Ivan Rupnik: Yeah, there’s a very interesting congressional report, where it just sort of lambastes the program. What happened: the energy crisis. Shipping big chunks of concrete around when you have an energy crisis was a problem, and it certainly impacted Operation Breakthrough, as did many other factors.

Vanessa Quirk: One of those factors? Politics.

Ivan Rupnik: Certain members of Congress were looking for an excuse to say that government should not be involved in housing.

Eric Jaffe: Right.

Ivan Rupnik: Congress went very far and said, “We’re not going to do research anymore on housing, we’re not going to do demonstration projects, public or not, this just proves we shouldn’t be involved in this at all.”

Eric Jaffe: But they did have to admit that Operation Breakthrough wasn’t all bad. It forced them to pass building regulations that streamlined the construction industry.

Ivan Rupnik: HUD developed a code, a specific code, for what we colloquially call the trailer home, but is actually also officially called the HUD code home. Within two years, you have a new program which takes advantage of those regulations, and it was able to provide truly affordable housing. Whatever we think about the quality of that housing, it’s probably one of the most successful federal housing programs, and certainly offsite housing programs, in the world.

Eric Jaffe: And it’s not just housing that’s seen success with factory-based construction. Since Operation Breakthrough, a lot of hotels and hospitals have also been built this way.

Ivan Rupnik: All the successes of the modular industry currently in the U.S. can strangely be linked to a number of regulations that were developed in order to support Operation Breakthrough. So a seeming failure creates a framework that is quite successful. Does that mean Operation Breakthrough was successful? I don’t know, but there would not have been that framework otherwise.

Vanessa Quirk: But according to Ivan, regulation isn’t the only path towards creating a framework for success for factory-based construction. It’s more about changing the building culture itself.

Ivan Rupnik: At this point, after maybe 10 or 15 years of looking at this stuff, I’m pretty confident that if we want to be serious about it, we need to work on lifting up the building culture as a whole. Otherwise, we’re not going to see a change in mass housing. We’re going to see some great examples. Some of them might be viable, some of them won’t. We’re going to see a lot of Habitat 67s, but we won’t see the kind of shift that we really need.

Eric Jaffe: So how do we lift up the building culture? How do we convince the players — the architects, the developers, everyone in the building ecosystem — that it’s time to take a risk on factory-based construction?

Vanessa Quirk: Yeah. How do we jumpstart this industry?

Karim Khalifa: Change is hard, right? Everybody in the ecosystem has to take a step in the same direction to make it work.

Eric Jaffe: That’s Karim Khalifa, the Director of Product Design for Buildings at Sidewalk Labs.

Vanessa Quirk: You may remember Karim from Season 1 of City of the Future, when he helped us realize the potential of mass timber, which has a much lower carbon footprint than concrete or steel.

Karim Khalifa: Mass timber is the material of the future. The reason you go to mass timber is really for sustainability, but when you combine it with the factory you get speed and quality.

Eric Jaffe: According to Karim, these three benefits — quality, speed, and sustainability — could really convince the building industry as a whole to buy into factory-based construction.

Vanessa Quirk: And getting to these benefits starts with changing the design process itself.

Karim Khalifa: If you think of how architects work today, they will buy a window from a catalog, or a door from a catalog. So why does everybody have to design a floor plate from scratch? Why can’t they pick a floor plate from a catalog?

Eric Jaffe: To help standardize the design process, Karim and his team are developing what they call an architectural kit of parts. It’s just four building parts — but like different Lego pieces, they can be combined in countless ways.

Lily Huang: The idea is that these four kit of parts could create an infinite number of different mass timber buildings.

Vanessa Quirk: That’s Lily Huang, an architect who works on the Buildings team. We asked her to break down the kit of parts for us.

Lily Huang: There are four basic elements that form our kit, and they are facade panels, so that’s everything that wraps around the exterior of the building, including windows, doors and everything that’s part of that envelope. And then the next part is the floor cassettes, which encompasses the floor of one unit, but the ceiling above so it’s really that sandwich that is in between a unit. It includes fire safety such as sprinklers. It’ll include mechanical, so the HVAC and ducts, and then it’ll include acoustic layers to protect the sound from traveling.

Eric Jaffe: So we have facade panels and floor cassettes. What’s the third element?

Lily Huang: The third element is the structural component so that’s columns and beams, and these are the elements that hold up the building. And the last element is our interior partition modular walls.

Image of rendered architectural parts
Sidewalk Labs is developing an architectural kit of parts for factory-based construction that can be combined in different ways. (Image: Sidewalk Labs)

Vanessa Quirk: Okay, so keeping in mind that the benefits here are quality, speed, and sustainability, let’s start with quality. Lily, how does the kit of parts allow you as an architect to make a really high quality building, you know, one that doesn’t feel cookie-cutter?

Lily Huang: Yeah, you’d think that only having four parts would result in boring buildings, but it’s actually the opposite. Having the kit takes away the boring aspect of the design and lets the architect focus on the more creative parts.

Karim Khalifa: We want to leave some creativity for a sense of place, and how an architect might want a space to feel to a community, or to a neighborhood.

Karim Khalifa: And look, just to be clear, our kit of parts is not going to make a Frank Gehry building, right? He will have stretched and broken our parts. But there aren’t that many Frank Gehry buildings out there either. And so most of us are trying to build really nice buildings that really perform well, and that have some character. And we think we can fit that mold. We can actually offer really good building materials and building components that are assembled to people who normally wouldn’t be able to afford them.

Lily Huang: We actually studied which real-world buildings we’d be able to make with our kit of parts, and we found we could make 90 percent of the buildings in New York City. So, with four parts, you can really create a huge variety of building types.

Eric Jaffe: And what about speed? How does the kit of parts help with that?

Karim Khalifa: Yeah, so by using the kit of parts we can develop factory process lines that, with their precision machinery, are able to shape pieces of mass timber at a very high production rate.

Parts such as floor cassettes can be produced in advance then transported to construction sites. (Image: Sidewalk Labs)

Lily Huang: Yeah, mass timber is significantly lighter than concrete and steel and therefore simpler and more cost-effective to transport, as well as assemble with one or two people per part.

Karim Khalifa: Our kit of parts is similar to Legos. Each of the Lego blocks has little dots on top and it actually has a recess in the bottom, so when they come to your construction site you can actually fit them together because they’ve been designed that way.

Eric Jaffe: So the pieces are designed for machines and factory workers to produce super fast, and they’re shipped to construction workers who are trained to put them together almost as quickly as Legos.

Lily Huang: And it’s also important to note that because the pieces have been cut so precisely with these machines, they come together like perfect puzzle pieces. Which isn’t just important for speed of assembly, but actually for sustainability, because airtight buildings require less energy to heat and cool.

Vanessa Quirk: That’s a really good point, Lily. So let’s get deeper into that sustainability piece. What are other ways that factory-based construction offers sustainability gains? Off the bat, I could imagine that this process must be less wasteful, since we know exactly how much material we need from the start and can make exactly that amount, nothing more.

Lily Huang: Yeah, and we would also have a bill of materials. So, each part would have X amount of wood, glass, fasteners, insulation, and with that, we would know the carbon footprint of each of these components, and of the whole building, before we’ve assembled it.

Karim Khalifa: So when you assemble the whole building, you get the list of kit of parts, you get the price of all of your parts, and you get the sustainability factor readout as well. So in today’s world, that’s really not — you’re not able to do that. You keep selecting materials and asking for data about its sustainability, and some materials have it and some don’t. But because we’re going to do this over and over again, we can now ask for the people that are supplying those materials to provide us the sustainability of that material.

Vanessa Quirk: And, with mass timber as the building material, Karim and Lily think we could take this idea even further. You could track not only the carbon emissions of a piece of timber, but even how sustainably it was harvested. And you could press the industry to keep improving.

Lily Huang: Recognizing that buildings are about 40 percent of carbon emissions, I think the way that we build now has to radically change if we’re going to address that. If we really want to address the climate change problem in the way that we need to in the next 5 or 10 years, we really need to change up the design process. And the answer to that, I think, is mass timber.

Eric Jaffe: And it’s this piece of the puzzle — the fact that mass timber is not just light and strong, but better for our planet — that might just be the most important piece of all.

Karim Khalifa: Manufactured buildings are a great opportunity to get efficient buildings built, but when you combine it with mass timber — which is a super-sustainable material — you’re ending up with a better building and doing something that’s better for the environment all at once.

Vanessa Quirk: And Karim isn’t the only one who’s bought into this idea. In fact, in the Pacific Northwest — a movement of factory-constructed mass timber buildings is already gaining momentum.

Susan Jones: So if I had to look forward to a city of the future, it would be a city that you could grow out of seeds in the palm of your hand.

Eric Jaffe: That’s Susan Jones, the founding architect of atelierjones and the author of a book all about mass timber. In 2015, Susan had the opportunity to build her dream house in her hometown of Seattle.

Susan Jones: So I really wanted to do something experimental that would be able to just bust out the doors and just say: “This can inspire, potentially, new, sustainable, lower-carbon technologies that will, who knows, maybe even change construction in the U.S.” And that was our sort of modest goal, but really we wanted to build an experiment for ourselves. And I’m happy to report that actually my family really likes the house. We’re still here.

Image of a wooden house with large windows
CLTHouse was constructed by atelierjones using prefabricated building parts. (Image: atelierjones)

Vanessa Quirk: Very important detail. So what was that process like designing for a prefab home?

Susan Jones: I’ll be honest, Vanessa. I felt really powerful as an architect. It was exciting to me because how many times have we been in design meetings as architects again and again, and had the contractor say, “You want to design that? Oh, that’s just way too expensive. And we can’t do that. No, we can’t do that. Nope, we can’t do this.” And I respect that. It’s a collaborative process and everybody’s risking a lot, and the owner’s risking a lot, and the contractor’s risking a lot, and they’re guaranteeing pricing, et cetera. But this is something that was really exciting because as the owner, I could say, “These are the panels I need.” I could have them designed the way I wanted to. And then actually, nobody could change it in the field, because it was already built. And so that kind of changed the balance of the designer being in charge of the project rather than the other way around.

Vanessa Quirk: I wasn’t expecting you to use the word “powerful.”

Susan Jones: I totally stand by that. These panels are kind of boring, and I’ll even say the word ugly. They’re awkward. Let’s just say that. And it’s your job to sculpt space and to make intersections, and repetitions, and buildings out of these that really reinvent the way we work with materiality. I feel like there’s a tremendous amount of freedom.

Eric Jaffe: So for somebody who’s not a designer, what are some of the benefits of building a home this way?

Susan Jones: First, the obvious one, that’s been talked a lot about with mass timber is the schedule. Hey, all these panels arrive on the site, you can put them up really quickly. If they’re repetitive panels, they might go up in four days for a small three-story building. Our house took about two weeks, frankly, because I had the great sense to start this process of putting the panels up in the middle of winter, which was really not a good idea in the blustery Pacific Northwest. But you learn from your mistakes in those areas. And so that can accelerate it, that process of design much faster. We can get onto the site faster. We don’t have to wait. And that’s a really exciting thing. And that’s going to lower costs.

Eric Jaffe: That is exciting. That’s really compelling.

Susan Jones: Exactly. And it’s even more powerful when you say, “Okay, great. So I can shave two months off this schedule. Wow. Okay. Well, that’s cool.” And it’s going to save the time of the labor crews on-site, and all those savings that go along with that extra two months. But now take it back even one step further and bring it into the developer’s pro forma. What happens when she can get tenants in there? What happens when she can start getting rent payments faster and add that to her equity payoffs, bank loans, et cetera. That’s where you get the real value over time and that really starts to add up. And I’ve now taken three contractors through this process, and it’s always worked out. So I do think we are at this really interesting tipping point.

Vanessa Quirk: Part of the reason that we’re at this historic tipping point? In 2019, a revolutionary change to international building code opened the door for more tall timber buildings everywhere. And Susan was on the committee that helped make it happen.

Susan Jones: I had the privilege or the bane or the responsibility or whatever it was, but I was asked to sit on that committee for almost three years pro bono work. And when those codes came out and you saw the green lights being pushed on every corner of this country of projects of developers that have been waiting for this, and all of a sudden projects are springing up. And these are tall timber buildings. This is either in design or in construction. And I don’t know these architects. It used to be, I knew every single architect who was in this space and called them up and commiserated. And there was this really strong community. And there still is, but it’s definitely broadened.

Image of a tall skyscraper made of wood
Changes to international building code have led plans for more mass timber buildings. Currently, Mjøstårnet in Norway is officially the world’s tallest timber building. (Image: Wikimedia Commons)

Susan Jones: And that’s exciting. I mean, both of our kids are really interested in policy now, which after that code experience, I don’t think they would ever would have had that. But they got to see first-hand the impact of a small gesture done by really one family, turn into this large, broad movement that ended up changing codes to build high-rises in cities that we’ll never maybe even see. That’s what’s motivating me is to look at my children’s eyes, my grandchildren’s eyes, some 60 years later and say, or maybe not in my case, but a few years later and say, “Dude, I tried my heart to change our construction industry, and I spent a hell of a lot of time doing that.” I love the design and I do love the prefabricated qualities and I love the idea of being a pioneer on the cutting edge, but I wouldn’t do it if it wasn’t replacing a material that is so dirty and so carbon intensive and so tied to our early 20th-century mindsets of how we build in this country.

Vanessa Quirk: Susan’s not alone. Her entire profession is finally starting to not just design sustainably, but to connect to the broader building culture. And, even more exciting, all the players in the building ecosystem are starting to think about how they could build better, too.

Eric Jaffe: And thanks to a new wave of innovations…

Vanessa Quirk: Including a building material that’s strong and sustainable…

Eric Jaffe: A new approach to designing buildings with manufacturing in mind…

Vanessa Quirk: And machinery that can speed up the jobs that construction workers do.

Eric Jaffe: Thanks to all these advances, factory-based construction is an idea that is finally ready to catch up to its promise.

Vanessa Quirk: And take off in cities around the world.

Karim Khalifa: You’re gonna see that people are watching these sustainable buildings be created and it’ll start shifting the entire industry. And I think that is what’s going to allow people to lean in and make this type of change.

Eric Jaffe: Thank you for listening to City of the Future, a podcast from Sidewalk Labs. Your hosts are Vanessa Quirk and me, Eric Jaffe. We are produced by Benjamin Walker and Andrew Callaway.

Vanessa Quirk: Mix by Zach McNees. Special thanks to Ivan Rupnik, Karim Khalifa, Lily Huang, and Susan Jones.

Eric Jaffe: Our art is by the great Tim Kau. Our music is composed by Adaam James Levin-Areddy. If you want to hear more of Adaam’s work, you can check out his band, Lost Amsterdam.

Vanessa Quirk: To learn more about Sidewalk Labs, visit our website, where you can subscribe to our newsletter at the bottom of the page. You can also follow us on Instagram.

Eric Jaffe: See you in the future.

Vanessa Quirk: Bye!