Q&A With Aleksandar Sasha Zeljic

Chicago's skyline, like those in cities around the world, is about to be populated by more high rise buildings.

Design Director Aleksandar Sasha Zeljic recently spoke with GenslerOn about the ways vertical towers and mixed-use design are affecting urban development and why cities are the engines of lifestyle innovation for the 21st century. Zeljic was also featured in an article about hi-rise development that appeared in Architectural Products magazine.

Talk about the rise of the vertical mixed-use buildings in Chicago and other international cities. Why are these buildings sprouting up?

Cities are facing growing pressure to plan, invest, manage, and govern more effectively, and they need impactful buildings that are both pragmatic and affordable. Vertical mixed use towers make efficient use of space and pull a host of amenities into a single building.

What we have seen in Chicago and other urban areas around the U.S. in the last several years is strong economic cycles marked by consistent growth in the residential and hospitality markets. There is still some sporadic new office development, and much of this takes the shape of traditional speculative tower form. But it is usually mixed with hospitality and/or residential programming in order to bring diversified offerings and to support more flexibility for developers.

For several years now there has been a strong push by Chicago city officials to make the city a more appealing destination for tourists and investors alike. This would, in turn, create a city that could compete, in terms of its real estate, with New York, L.A. and San Francisco. In addition to investing in public spaces, retail, and venue spaces, we also need more hotel rooms and residences for people to lease, buy, or invest in for the long term. There is clearly a direct correlation between what the market demands and why developers are looking at markets like Chicago at the moment.

As these requirements grow, land gets scarcer and more expensive, so taller buildings become more prevalent as a logical and cost-effective response. New York is a great example: cost per sq/ft in newly developed condos in New York is a staggering $8,000-$10,000/sf. We have yet to see that in Chicago.

What will be the biggest challenge in designing successful buildings for cities like Chicago and other international destinations?

The world is embracing mixed use, and it often takes one of two forms: high-density urban districts that are transit-served and alive with activities, and urban centers outside the core with similar characteristics and a lower density. Both share an interest in urbanity that reflects a hedge-your-bets desire for flexibility. Mixed use stays fresh by curating offerings and 24/7 events. The goal is to attract the best tenants by creating amenity rich, transit-served destinations.

Across the U.S., as well as in Asia, some parts of Europe and Latin America, cities are increasingly becoming choice destinations. People want to live, work, and play in cities. Cities are the instigators of and locations for “lifestyle revolutions.” In the past, work drove people to the cities and was the primary reason for deciding where to live. Today, people are choosing to live in cities based on what the overall brand of the city is. A city’s brand is defined by what that city offers in terms of additional program elements. It’s about how it can support life beyond work.

When you look at individual buildings, they represent the very tissue of the city in its most basic form. Success or failure of cities is dependent on the correlation between individual buildings that, along with their programs, create neighborhoods and districts where residents interact through public space. Our biggest challenge in the future will finding ways to enrich human experience in all areas, especially where people interact with buildings and public spaces.

With all this new construction, do we risk materials scarcity?

We are certainly using more resources than ever before, and construction materials and fabrication processes have become commoditized. What used to be a normal product in the past may become prohibitively expensive in the future. As a consequence, this is likely going to have a negative impact on the cost developers have to bear, and it will force them to consider alternative materials.

While material cost and scarcity create challenges, it also opens up a door for innovation in research, for exploring new ways of using known or traditional materials, for coming up with new synthetic compositions, etc. Gensler has researched different ways to use traditional materials, like glass, wood, and concrete, in untraditional ways, and the results have been very interesting.

What infrastructure considerations will cities have to take into account as they continue to grow and evolve?

Infrastructure is being profoundly affected by urbanization. The United Nations and World Bank are expecting another 2.5 to 3 billion people to move into cities around the globe in the next 30 years. Some cities have outdated infrastructure that will have to go through major changes. Other cities have very little infrastructure to begin with and will require major investments.

This is an ongoing challenge that we have to be smart about, and each city will face it in its own specific way. Consider a recent debate in Chicago. The South Loop has recently announced six to eight new towers that are planned for construction in the next two to six years. These towers will feature a range of about 2,500 plus new residential units and create a gravity center at the intersection Roosevelt and Michigan. During public reviews, the single most important concern expressed by community leaders was a negative impact on the neighborhood’s existing infrastructure, roads, public transportation, etc. We must address these concerns head-on.

What role will resiliency play in the future of cities?

I think it is hard to talk about resiliency in the context of tall and super-tall buildings, as they require massive investments, they take a long time to construct, and more than any other type of building they are extremely prone to the negative impact of uncertainty. I think that successful developers need to have strong and very informed visions that go beyond the immediate rate of return and consider long-term sustainability and resiliency measures. I also think that buildings have to be designed to allow a degree of flexibility so that they can adapt as cities develop.

One of the things we are seeing with our heritage supertalls in Chicago—the Willis Tower and John Hancock—is that there is a continuous effort to find new ways to reintroduce public space inside of the buildings (Ledge, Tilt, etc.). Doing so improves and elevates the human experience by creating inclusivity and various levels of engagements. We also know developers are looking at ways to broaden the amenities featured inside new buildings. I think creating opportunities where buildings become platforms for active interaction and public engagement will foster resiliency in the long run.

How will green and sustainable technologies impact cities in the near future?

I think green and sustainable technologies are having their impact on the built environment, but perhaps not as much as most of us in the design industry would like to see. Some of the strategies that used to be at the forefront, like high performance glass with argon gas filling, wind turbines, rain water collectors, are now mainstream technologies. Newer technologies are still being scrutinized to see if they can tangibly reduce investment costs and save resources. The dialogue in our industry has shifted from purely looking at the implementation of green technologies as a measure of performance into understanding multiple relationships that affect performance. This allows clients to closely relate the implementation of such measures to the successes of their business.

What existing tall buildings exemplify the push towards encouraging sustainability and wellness?

In the last two to three years, projects like Bosco Verticale in Milan and One Central Park in Sydney had very specific designs that integrated outdoor space, vegetation, and landscaping as part of a wellness strategy for residents. We have seen similar concepts in Singapore and other Southeast Asian cities, where mild climates allow this concept to take hold.

These projects are examples of innovation at work. Shanghai Tower integrates vegetation, sky gardens, coffee shops, and restaurants into 12-15 story atriums that are distributed vertically throughout the tower. These atriums effectively create a passive concept of high performing double skin façades, another unique element of the building. Shanghai Tower is recognized as one of the world’s most sustainable supertall buildings, achieving LEED Gold and China Three star ratings, and it is a great example of where we can go. Gensler also recently completed the tower at PNC Plaza in Pittsburgh, which is, at this time, the most sustainable and eco-friendly tower in North America. These buildings show that developers are now prioritizing the wellness end users and the health of the environment.

Sasha Zeljic is a regional practice area leader for Commercial Office Buildings in Gensler's Chicago office. With a strong emphasis on research and implementation of sustainable design, Sasha is particularly interested in exterior envelopes and conceptually advanced high-performance building façades. Contact him at aleksandar_zeljic@gensler.com.