From tall towers to multi-building districts, mixed-use design has become one of the defining opportunities of contemporary urbanism. In this episode of our Roundtable video series, KPF Principals Elie Gamburg, Marianne Kwok, and Rob Whitlock sit down for a wide-ranging conversation exploring the firm’s approach to mixed-use design.

Over the course of the conversation, the three discuss how zoning has historically driven—and constrained—the evolution of mixed-use towers, from the bonus-zoning incentives of the 1980s to more recent performance-based approaches; how the stacking of programs often determines the exterior form of skyline-defining towers; how transit infrastructure acts as a catalyst for some of the world’s most successful mixed-use developments; and how rethinking “use” beyond conventional real estate programs has the potential to create richer, more resilient cities.

Launched as part of KPF50—the firm’s year-long celebration of five decades of design excellence—the Roundtable series brings together firm leaders and professional associates for conversations that explore the evolving challenges and opportunities pertinent to a designated sector of KPF’s practice.

From left to right:

Elie Gamburg: Elie designs innovative solutions that address some of the most pressing urban and architectural challenges that face cities today and in the future. His projects range from the transformation of 8 Canada Square in Canary Wharf from a single-use office block into a vibrant, mixed-use development to a vertical campus for NYU Shanghai that synthesizes diverse programmatic requirements into a highly connected and unified whole. A global leader in the design of innovation districts and campuses, Elie chairs the NLA Expert Panel on Innovation Districts and has taught design at Cornell, Harvard, Columbia, NYIT, and Tongji Universities.

Marianne Kwok: Marianne is a driving force behind the firm’s portfolio of mixed-use projects as well as a leader in applying the thinking behind mixed-use design—that diversity is key to vibrancy and resilience—to corporate headquarters and residential projects. Her projects include major mixed-use districts, such as Hudson Yards in New York, as well as commercial buildings where a richness of program establishes the office as a complete neighborhood, such as TP-LINK LXD in Shenzhen. Marianne has taught studios at Cornell University and served as a guest critic at Yale, Pratt, NJIT, and Harvard’s GSD.

Rob Whitlock: Rob is a global leader in the design of tall buildings and mixed-use urban complexes that generate urban vibrancy by integrating mixed-use program and cutting-edge sustainability. Several, including 18 Robinson Road in Singapore and Hysan Place in Hong Kong, work to elevate the public realm by carving out space for greenery within a major tower, enhancing the urban experience and shaping the building’s architectural gesture. A Fellow of the AIA for more than 35 years, Rob frequently serves as a guest lecturer and presenter at conferences including CTBUH and the Green Building Conference.

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Rob: Hi, I’m Rob Whitlock and I’m here with my fellow partners, Marianne Kwok and Elie Gamburg to talk about mixed-use design; something that I think is pretty fundamental to the the zeitgeist of KPF these days. In the first decade of KPF, the only mixed-use project really was 900 North Michigan Avenue, and that stacked residential over hotel, over office, over retail.

And the interesting thing about that, I think, is that each of those uses had an address on a different street. So it was almost like it was a single use building as far as the user was concerned. Whereas I think about the way we use mixed use now, it’s really about activating cities and finding unique ways to bring programs together.

Elie: That marks a shift of mixed-use buildings in geography over time, and I think one of the benefits of being a global practice is that we get to follow these ideas around the world. So the mixed-use building, in a way, really starts vertically in New York and Chicago—of which 900 Michigan was one of the later examples—and then all of a sudden it stops here completely as a result of zoning and changing approaches to commercial development. But it’s reborn in a hyper-intense way in Asia, and then migrates 20 or 30 years later, back to America and Europe.

Marianne: Our ethos is to make the city better and I think mixed use really does help with that, because it animates the city and gives it life. I think in a lot of North American cities, for so long because of zoning, everyone lived in the suburbs in a house, and then they went downtown to an office building to work, and then at five the downtown of the city would clear out and there was no life. And now I think it’s completely the opposite.

RW: It’s interesting to think about the way cities have used zoning to introduce mixed use, like when we worked on Brickell Arch—on Brickell Avenue south of downtown Miami—it was just banks and insurance companies, and it was dead at night, as you say. But they wanted to find a way to regenerate that part of the city, so they gave you a 30% zoning bonus if you made it mixed-use. So that was the genesis of that project. It went from just being an office building to being office and hotel, and then condo was mixed in. So it was very intentional on the part of the city to say, look, we have to do something different because this is not a fun place to be.

MK: The interesting thing about zoning is the idea of performance-based zoning, which is what One Vanderbilt implemented, and it preceded the whole East Midtown rezoning effort. You know, we helped facilitate that! And I think this idea of performance-based zoning could result in more mixed-use towers, because it’s not so frozen with setbacks and “you have to do this, you have to do that.”

EG: Are there particular neighborhoods that you guys have both seen evolve over time?

RW: Well, I was thinking earlier about Singapore, which, when we started working there, was still using planning derived from 1965 CM thinking about “you have the office here and the residential there and retail there.”

And the first couple of buildings we did there followed that model. Then in the early 2000s, they realized that if they wanted to become a desirable international city, they needed to become more like London or New York, where uses were mixed. So that’s when they adopted the idea of live, work, play, and very actively went about remaking the city to bring mixed use in.

EG: And in a way, some of our early projects in Singapore, like Marina Bay Financial Center, were sort of the first steps in that direction, right?

RW: Exactly.

MK: In Singapore, the sites are very small. 18 Robinson Road, which is mostly office, also has a mix of public park.

MK: And an observation deck at the very top of the building is actually a really great thing! It’s usually occupied by a penthouse or by a boardroom, but that the public gets to enjoy these great views of the city is really fantastic. And at 18 Robinson Road there’s not just one park, there’s two!

RW: Yes, multiple.

EG: And then there are other cities where that’s happened as well, right, Marianne?

MK: Well, there’s Hudson Yards in New York City, which is really a mixed-use district.

EG: Did you find when you were working on Hudson Yards that there was a lot of discussion about the relationship of the podium pieces, the towers, and the High Line in terms of how you mix the uses?

MK: Oh, yeah! I think we wanted as much connection to the fabric of the city as possible, and of course that was difficult given that we had to build a platform and there was a train yard below us. But the sloping of the site really helped because 30th Street is quite a bit lower than 33rd Street, and 33rd Street is almost at the same height as a High Line. So the platform was able to be at the same level as the High Line and makes 30th Street one of the most interesting streets with these multiple levels. There’s a High Line level that’s super activated—that’s where the shed is, which has entrances both at 30th Street and on the platform level. There’s a food hall. So it’s really this multi-level experience, and I think that we’re really quite good at that.

RW: It’s interesting to think about the transformation of mixed use in Asia because initially, in places where there was no infrastructure, they built one of everything on a block. So you had office and residential and hotel next to each other so that it sort of functioned as a mini-city. And then I think about the hyper examples in China, the supertall mixed-use towers, which is, to me, one of the most fun things, where it’s just irreconcilable programs with irreconcilable structure.

MK: It really is like a vertical street, like Lotte World Tower.

RW: That really probably is the most supercharged mix of uses. I still think one of the most brilliant diagrammatic comparisons was from Paul’s Thinking Big presentation, where he compared the programmatic section of Lotte with the Plan of Regents Crescent and all of the parks and public spaces that were along that dominant street were in lot transform to public spaces over the height of the building, like we almost do that diagram a disservice, because we think of it so literally as just the the plan thing turned vertically.

EG: There’s something really fun also about the formal opportunities that this creates, right? Because there are times where you actually stack these things up very neatly, and as the size of the floor plate gets smaller and elevators drop out, you can kind of taper the tower. Then there are towers that actually split as they go up.

RW: Right.

EG: So you have ICC and Shanghai World Financial Center, which both use either internal atria or, you know, the void at the top, as a way of absorbing area. So it’s fun to think about the formal ingenuity that it takes to make these buildings work.

RW: I also found that reconciling the different planning dimensions for office, residential, and hotel, all in the same building, with the 100 hundred elevators that are required to make it work, like a problem solving effort. The form became a result of optimizing each of those things and finding out how to stack them.

MK: I don’t think you can ever work on a mixed-use tower without having worked on each of those program types separately, and really know what a hotel is, or really know what a residential apartment needs.

RW: Yeah, I mean, I think the CITIC Tower in Beijing, to me, was the extreme example of that. And of course, being in the worst possible seismic zone that you could build in we allowed the floor plates at the bottom to be as large as possible, because of the size of the core and the planning dimensions, and then tapering as the elevators drop off and the use changes. In the early design phases it had hotel, it had residential—and that’s where the form really was derived from.

MK: We spend a lot of time on the tower itself and, you know, the core, but I think we spend an equal amount of time on how the tower meets the ground plane.

RW: Yeah.

MK: And I think that is so important for us, that the relationship to the city animates the space and that we’re trying to make sure that these towers do bring in the context.

EG: I think it’s one of the ways that we differentiate ourselves from other architects.

EG: And part of making the context successful was always trying to find ways that the uses adjacent to the tower could become integrated. So you see—from our earliest mixed-use projects like Roppongi Hills or Jing An Kerry Centre in Shanghai—a kind of thinking at multiple scales. So you have the ground plane, with activations there, then what’s happening right below the ground, but also the podium, to the low towers, to the taller towers; and that diversity of scales marries to a diversity of uses.

RW: Well, maybe you could talk about 8 Canada Square because I think that’s a really interesting transformation.

MK: It’s so exciting!

EG: So at the top of the building, as the core starts to drop off, there’s not enough elevators to serve a 21st century office. But there are enough to do hotel and a dining and leisure destination. So a part of the formal changes to the building was reconfiguring the top to allow the hotel to respond to what the core could actually handle. So that’s a way of taking, actually, an envelope that was too large and readjusting it to create an active set of uses.

What’s also interesting is the role that this building has in taking Canary Wharf—which is a neighborhood you’ve done a lot of work in, Marianne—and transforming it into a mixed-use neighborhood. Because that’s a neighborhood that was an archetypal single-use office district and it’s been working to get residential and retail successfully integrated into it. So now we can also take that opportunity to mix uses in the building.

MK: 8 Canada Square is also really interesting because, even though it wasn’t built that long ago, the idea of workplace has changed so much and a building’s porosity and its relationship to the outdoors is so fundamental now. So what you’ve been able to do is pretty incredible to this sealed box.

EG: I feel sort of similar about the work that you've been doing, even on what we might consider a traditional single-use building like the Lianzhou Building, because, as you mentioned, workplaces are evolving. So even for a single-use workplace, we have to add all sorts of other uses to it to make it very lively.

So I think the mix of leisure uses, athletics, and dining that you were able to add into the middle of this very efficiently laid out tech office building is actually pretty amazing, and I think speaks to the transformation of workplace over time.

MK: Yeah, office isn't so boring.

EG: No, it's actually super fun these days!

MK: Yeah, because we think of it as a mixed-use building.

EG: Yes, and I think with residential as well, we're kind of thinking about all these program types as potentially becoming mixed-use themselves.

MK: Yeah.

RW: Yeah, I find it interesting, because of zoning in New York, how few mixed-use buildings there actually are. I think maybe five, and one of them being our 520 Fifth Avenue across the street, which is residential over office with club use.

RW: But in some cities, mixed use is the default thing. Developers like it because it hedges economic cycles, your eggs aren't all in one basket, the code is more accommodating... In some cases they're almost insistent upon it!

MK: And then I think the need for sustainability too is so paramount.

EG: I mean, there are a lot of efficiencies, right? There's load sharing in terms of parking, water, heat, electricity, and also being able to just use existing infrastructure and neighborhoods throughout the day.

RW: A couple of years ago we completed Thamrin 9 in Jakarta—which is a site that the family spent two generations compiling, right in the middle of downtown Jakarta, and then built two mixed-use towers. Each is office, hotel, and retail. There's a podium that—and we should talk about Nagoya in a minute— has nine stories of retail with performance theaters and bowling alleys. The problem in Jakarta is that everyone lives in the suburbs and the traffic is so bad that no one wants to leave at the end of the business day, so they've created this environment where people can spend time with their families, and when traffic dies down, they can make their way out of the city. But it's a remarkable little enclave in the middle of a city that hasn't really thought about a mix of uses in that way.

MK: That's amazing.

EG: But as you mentioned with Nagoya, I think there's also a certain concept of the "sticky neighborhood," or the "sticky campus" or "sticky city," where there's actually a benefit of getting people to stay around for longer, even at transport nodes. Right?

RW: Well, I think at the JR Central Towers & Station in Nagoya, Japan, being a transport node is really important to why we do mixed-use buildings in the first place, because we can build supertalls over a major train station. I think this multi-layered strategy, like going all the way down to subterranean tunnels with trains—I mean, my big take away as a young architect here at KPF was the idea of the "sky street," the replicated ground plane, where you have all the parking stuck in between the public lobby adjacent to the high-speed rail tracks. So, there are essentially two ground planes, one for the station, one for the project, and then the sky street above with the wedding chapel. And all of those uses form a little village within a high-rise development.

EG: The other thing I think is really important is this idea that all programs succeed most when you think about them experientially.

MK: Yes.

EG: I think if there's one through-line that you can see in a lot of the work that we've done as a firm, it is moving from thinking about these things as pure typologies to actually experiences. So a transport node isn't just a place where you can catch trains, but you can get a cup of coffee, get married, go to a park, enjoy life.

MK: All in one day!

EG: And then you fast forward 35 years to Changi Airport Terminal 5. And again it's the airport as experience and not just a shopping mall, and think about all you can do: you can run, you can sleep, you can go to the spa, there's going to be offices there. And you see that also in our educational campuses.

RW: I thought maybe you could talk about NYU Shanghai and how that brings all these different programs together. No wedding chapel though, right?

EG: No. Although it does have the biggest rooftop farm in Shanghai.

MK: Wow.

EG: Singular points of pride! But you get the students involved, right? And all of a sudden, anything can happen. The building has so many different terraces—the building itself is a stack of different uses and every use had its own terrace. But in some cases there were almost more terraces than we could invent uses for. So we started to engage the students and a bunch of them came together with professors and said, we'd like to start a bee colony. So there's a yoga terrace and a bee colony.

MK: There you just don't mix.

EG: Yeah, you don't want to mix that!

But there is something wonderful about the idea that putting the uses together is more than the sum of their parts.

MK: Yes.

EG: So academically, the example at NYU Shanghai is the way that all the different components of the campus are integrated together. You can have a program where the technological classrooms for engineering and sciences and the business classrooms are in close proximity, so a new set of classrooms for what they called Interactive Media Arts emerged—which are classrooms that can be sometimes for digital programming, sometimes for business, sometimes for making or fashion. That's a kind of program that could only exist at the intersection of these different entities.

MK: I think, as you were alluding to, the same thing can be said to happen in hotel or residential or office where the bringing together of different uses allows new kinds of uses that couldn't otherwise exist, because the idea of different uses is also about the connected city, connective urbanism. And I think what is really amazing is that high-speed rail from Hong Kong to Shenzhen to to Guangzhou, and above each of those stations is a KPF building. So there's ICC, there's Ping An Finance Centre and then there's CTF Finance Centre.

RW: Yeah.

MK: And they're all supertall mixed-use buildings.

EG: And one of them is about integrating directly into the station, and then it has a kind of singular form that splits at the top and there's an atrium in it. Another is actually the diminishing form typology, so getting smaller as it goes up and it has this really elegant slender proportion because of the way it diminishes. And then CTF has this incredible spiral where it diminishes as well...

MK: And the stepping, so there's outdoor space for each of those volumes at the top.

RW: Yeah. I was also just thinking about Hysan Place. It was replacing a building built in 1985, which was built on a combination of New York 1915 zoning where you had a three story podium and then a 65% tower. But this was in the middle of Causeway Bay, which is the most retail intense part of the world!

But Hong Kong was starting to look at setback zoning, so in exchange for 10% open space at grade, it was a graduated percentage of site coverage as you went up. The scheme that we ultimately developed was unique in that it had ten floors of retail, but those were supported by a sky street for the office which sat above that.

So the retail could be fed from above and below, because the composition also has a series of public open spaces over the height of the building. So again, vertical village but helping them rethink the way zoning could support and expand a city that was trying to redefine itself and make itself more accessible to its residents.

EG: I was in Hong Kong literally three weeks ago, and this is a project that's maybe 10 or 15 years old now, and it's just been so absorbed into the mental map of the city for people. So over the course of a one week period, on four separate occasions, somebody would say "we should meet at Hysan Place." And what was really great wasn't just that they said Hysan Place, they would have to say where in Hysan Place. So it would be on the sky terrace with the restaurants, or there's a game terrace now that's been programmed for outdoor games. So just the idea that you think of the building as an extension of the city, and it becomes this place where you just meet there and go somewhere else! But that's where you meet coming out of the MTR.

MK: I like to think about the idea of a mixed-use building and that kind of expanding into a mixed-use district, or a mixed-use neighborhood, because they all kind of do the same thing. They activate a portion of the city to give it life throughout the day.

RW: Westlake 66, Jeff's project, it's basically village making. Sort of high-rise, but a number of parcels stitched together, all with second level pedestrian connectivity. So it takes parts of the city that might otherwise feel like disparate lots and finds a way to weave them together.

EG: It's kind of this horizontal mixed-use typology. And I guess that's a little bit like NYU, too, where it's more horizontal than vertical.

MK: And overlapping.

EG: We tend to as architects, or maybe developers, talk about use in a very defined way. We're often referring to office and hotel and residential and retail. But actually a city has many uses. The High Line, you know, park, outdoor space, a promenade is a use, food halls are uses, cultural facilities like the shed are uses. So use is not necessarily just like a real estate program. There's so many ways that we use a city, and I think there's a natural flow from that to something like Westlake 66, where the roof of all the retail is actually a kind of High Line-Like connection that brings all these different buildings together.

RW: Yeah.

EG: And I think it's an inevitable result of in the intensification of cities. So even cities that were formerly fairly low density, like Austin, Texas, as they start to grow denser, the first crop of buildings are just residential or just office. And then as the downtown becomes more and more lively, there starts to become opportunities like Waterline, where you all of a sudden have a park coming off the river. And then a form that is just the pure expression of each of those uses, and theyre you're going back to integrating strategies, because actually they're all separate. There's like a little sky garden between each of the elements that you can read.

MK: Yes.

RW: But I think it's really encouraging how many mixed-use masterplans and projects were doing in the United States. In Florida, in California, in Texas, and Utah.

MK: Exactly.

EG: So skiing is a use. It counts as a use!

RW: I suppose I'm just thinking about the fact that even we don't talk about any of these single uses the same way any longer. The office lobby looks more like a hospitality space than a rigid office lobby, and that sort of transformation of thinking is actually applying to all of those uses. Everyone is rethinking exactly what it means to be residential or hotel or office.

EG: The other thing I really enjoy is this idea of creating opportunities in the city that are really inclusive, because not every space needs to be somewhere somebody has to buy something in order to be able to access. And I think that's true of Hysan Place. Many people have used it as an extension of the city to be able to just meet with people. You don't necessarily need to buy a coffee; it's great if you do! But it's a way of bringing people together because it's creating an environment that's conducive to socializing. I think that's part of making a vital city. And you see it in the sort of evolution of central business districts into central social districts. And a key ingredient of that are buildings that have those elements of the public realm that are able to bring people together.

 It was two mixed-use projects at KPF that made me want to work here. The ones that I fell in love with early on were Baruch College here in New York, which is literally a vertical campus that has eight different schools in it a library, a performing arts center, a gymnasium, just everything short of the dorms—and so obviously it was thrilling to get to work on something like NYU Shanghai 30 years later—and the other one was Roppongi Hills.

MK: Well, it was one of the earliest mixed-use neighborhoods.

RW: It's just so amazing, both because of the mixed use, but also the idea that you build this monster tower, but then it allows for an enormous amount of public open space and grade and the weaving of those programs together.

MK: That was like where you see things that you never really thought could work. There's this subterranean hotel drop off, right? But it works.

RW: Yeah.

EG: It also speaks to the resiliency because it's still considered one of the number one destinations in town. And it hasn't wavered at all as just being in the consciousness of people, when they talk about the city, sort of like the destination.

It's interesting to think about mixed use, not just in terms of the projects we do, but the cities that we love to spend time in. And I think many of the cities that that I personally most enjoy are the ones where the mix of uses is most intense. Tokyo is such a great example of that, where almost every neighborhood is such a diverse mix of uses and and every building within that neighborhood has something different on the third, sixth, 19th floor. So just as a visitor, but then also as an architect, it's such a great environment to think of all the ways you can combine and recombine programs.

RW: Yeah. I like Hong Kong Central and Hong Kong for that.

MK: Also wherever we have our offices, we are so lucky because we have Covent Garden—

RW: I love Singapore as well.

MK: Yeah, In Singapore there's a hawker centre right by Robinson Road. But in Hong Kong with central, it's all about the section and the layering. You know, our office is there, we stay in a hotel that we've designed, it's very thrilling.

EG: And then even here in New York we're right across from Bryant Park, which has a library.

MK: Yes.

EG: It also has an exhibition space, retail, residential, restaurants.

RW: Yeah, very vital.

MK: This was so much fun.

RW: We should do this more often.

EG: We should, and we should go grab a drink now.

ALL: Thank you, thank you, thank you. *clink*

This interview has been lightly edited and condensed for clarity. The full conversation can be found in the above linked YouTube video.