“To have an affordable tall building, it has to be like a Swiss watch”
Bill Baker is an American structural engineer and consulting partner at Skidmore, Owings & Merrill (SOM) in Chicago, USA. He has been working on tall buildings since the early 1980s and is best known for the engineering of the Burj Khalifa, the world’s tallest highrise structure.
Bill Baker is an American structural engineer and consulting partner at Skidmore, Owings & Merrill (SOM) in Chicago, USA. He has been working on tall buildings since the early 1980s and is best known for the engineering of the Burj Khalifa, the world’s tallest highrise structure. We spoke with him about the interdependencies between vertical transportation technology and highrise construction, how they are integrated within practice at SOM, what design opportunities this offers and which developments to expect in the future.
topos: Bill, thank you for the opportunity to speak with you! I have a set of questions on highrise buildings, vertical transportation and urbanization. Which actually drives which? Some people say building skyscrapers is the driver, there are others who say elevators and vertical transportation technology are the driver. There are possibly more, such as economics or challenges of urbanization. What is your take?
Baker: Well, if you go back to the very first skyscrapers from the late 19th century, the drivers were structure and vertical transportation. That really hasn’t changed. They are the dominants in the generation of a tall building. The structure to hold it up against the forces of nature and the vertical transportation to make it useable. Those are the technologies that are constantly evolving to the next level, and they are certainly dominant. The whole issue of tall buildings, depending on scale, has to do with urban density. We know that high density urban environments are much more efficient, use less space, are more energy efficient than the kind of sprawl that you can see all around the world. A key part of that is the issue of transportation, and I think its the drive for density that both the structure and vertical transportation are reacting to.
topos: The logical conclusion would be that if urban densities are increasing, then the need for vertical transportation systems increases as well?
BAKER: Oh yes, definitely. It’s also about trying to be more accessible. Plenty of vertical transportation solutions are made for people who are handicapped or are elderly. Even in shorter buildings, it can become impossible to walk up a set of stairs. Vertical transportation offers a solution for that, and therefore, has something to do with equity as well.
topos: So especially in the US, that relates to the Americans with Disabilities Act (ADA)?
BAKER: Oh yeah, it’s a big driver. Even in single family homes, people have to sell their homes after a certain age, because they can’t deal with walking up or down the stairs.
At SOM we’re an integrated practice of architects and engineers. Architects who like working with engineers, engineers who like working with architects.
topos: In terms of practice and in the case of very tall buildings, how do you achieve an integration of vertical transportation, construction engineering, architectural and urban design at SOM?
BAKER: At SOM we’re an integrated practice of architects and engineers. Architects who like working with engineers, engineers who like working with architects. And they work very closely together. Everybody has a different area of expertise. That doesn’t mean we don’t calm up on each other’s work, either. There is a lot of give and take. It really does come together in the core of the building, in the center of the building. In vertical transportation, a lot of times that is where the stairs are, power risers, telecommunication risers, all together. To have an affordable tall building, it has to be like a Swiss watch. And it takes a lot of work, a lot of design and conversations. When we worked on the Burj Khalifa, there was a tremendous amount of give and take on the core. The architects would propose a core, and then we would counter-propose to that, and they would counter-propose to our counterproposal. And eventually, we got something that was very much appreciated and satisfied all needs.
topos: That’s interesting … it makes it almost sound like sport!
BAKER: Well, we do challenge each other, to be direct.
topos: Looking at recent developments, at how these vertical transportation and highrise building concepts develop, what is the most significant consequence of advances in this area?
BAKER: Let me speak about the single tower. Some of these systems are going to have a radical effect on the typology of a tall building. It’s possible that you have less shafts, and less of your real estate would be used up by these vertical shafts that you need for vertical transportation. If so, then the core gets smaller. As consequence, many systems would change. The layout of a building would change and tend to get smaller. As the core shrinks, the entire building would change. In many buildings in the 30 to 40 storey range, the core, meaning the concrete walls built around the elevator, the stairs and the lobbies and the bathrooms, they serve to take up the lateral loads. They are the backbone of the structure. As that gets smaller, all of a sudden you need a new system, because buildings will become too slender to reach the desired height. There will be corresponding innovations in structure and the architecture goes along with this. So that will be the difference.
topos: Back in the day when I studied architecture, the ratio was 1/10 in terms of slenderness, but it seems that buildings can be a lot more slender these days?
BAKER: There are a lot more slender buildings. But often, they are very, very expensive. In the case of some of the pencil buildings, if you look at the use of concrete per square meter, that’s a bit pricey, in an environmental sense. I think there are practical limits as to how slender one should go compared to how high one might go.
topos: It seems there is a point where it is no longer economically feasible.
BAKER: Well, it depends on how rich you are!
topos: Of course, that makes a lot of sense … I totally forgot that! [laughter]
BAKER: These very super-slim buildings are super-expensive.
topos: Now we have a field of tension between vertical transport’s potential to make buildings accessible to people with disabilities and spaces up in the sky that are only accessible if you have a wallet that is thick enough. Is that simply part of the urban condition?
BAKER: No, it doesn’t have to be, that’s just the super-slender buildings. Normally proportioned tall buildings can be pretty affordable, and are likely to become more affordable if you will be able to have quicker vertical transport. I think the future will show that. We’re expecting a few more billion people to show up in the next generation. Let’s hope these people don’t cause too much sprawl.
topos: That’s a really interesting point and leads into my final question. If urbanization is going to continue as projected and we don’t want to create sprawl by moving into the countryside and cover greenfields with new development, we have to go up. Would you agree with that observation?
BAKER: Yes, but it doesn’t mean a highrise building has to be super-tall. There is a tremendous amount of density possible with midrise buildings. A lot of times the really tall buildings are an urban marker that tell you where the center is. That kind of urban development is centered around public transportation. It’s really effective if you can have people move around the city that way without having to use their own car. Another big development is car sharing and self driving cars. There will be radical changes in the very near future. We are currently designing buildings that have several levels of parking that are designed to be converted into office space. Our developers are seeing that if you design a building that is going to be around for a long, long time, some of your prime real estate might become obsolete. I think it is smarter to develop something today that can be used in the future.
topos: So adaptability is key?
BAKER: One of the most sustainable things you can do is to not knock down a building, and instead, keep using it.
topos: Very true!
BAKER: In addition, our energy systems are getting better and better. Some of these older buildings are not so well insulated. Power, energy is based more and more on renewable resources, so it’s not as much of an issue as it has been a few years ago.
topos: Final question! Assuming that designers and engineers really want to do something that hasn’t been done before, what are you looking forward towards most in this area of vertical transportation and highrise buildings?
BAKER: Just more effortlessness of it. We’re getting to where, a little scary somehow, “it knows you’re coming”! [laughter], and the building system knows where you want to go. A few years ago destination control elevators became available. There are no buttons inside the cabs anymore, and instead, you push a button in the lobby and the system tells you to go to car B and you get to your floor. Nowadays if you’re in some of these buildings, they know you’re there, they know where you want to go and something will tell you, “Mark, you should go to elevator E.” So off you go!
topos: So buildings will more and more become our “friends”, in a quite literal sense?
BAKER: Yes, but having been raised in the era of reading 1984 and that kind of stuff it’s a little scary to me!
topos: That’s true! [laughter] I guess, any technical innovation has pros and cons. It’s like a bread knife, you can cut a loaf of bread and you can hurt somebody.
BAKER: Yeah, and it’s definitely the future.
topos: Very well, thank you very much!