A Bit More Detail

Assorted Personal Notations, Essays, and Other Jottings

[URBAN NOTE] “The Willis Tower In 150 Years: Adapted, Demolished or Abandoned?”

Writing for WBEZ, Jesse Dukes and Jen Masengarb lead an interesting thought experiment: What will become of Chicago’s Willis Tower in 150 years? The answer, they suggest in their fascinating piece, has much to do with what will happen to Chicago generally.

When Chicago was still celebrating the end of the Civil War, the city had a population of roughly 200,000 people. The most memorable structure from that era, the Water Tower, was still three years from construction. Today, 150 years later, the city’s population has grown by more than 1,200 percent, and the city’s tallest building, the Willis Tower, is more than 1,300 feet taller than the height of Chicago’s tallest building in 1866.

This is all to say a lot can change in 150 years. Which makes our question, from engineer Bill Muscat, pretty challenging:

What do we do in 150 years when our current buildings are too old? What do we do with an old Willis Tower?

Bill asked because he’s noticed that some of Chicago’s earliest skyscrapers — buildings he considers iconic — have been demolished recently. The first generation of skyscrapers is about 120 years old, so he picked a timeframe of 150 years, figuring that the Willis Tower would be pretty worn out by then. The tower was originally constructed in 1973 for the Sears Roebuck & Company headquarters, then renamed in 2009 by Willis Holding Group, who obtained naming rights as part of a lease agreement.

Bill’s question is based on the premise a building can become “too old.” That’s only partially true. The structural steel in a building like the Willis Tower could last for thousands of years, as long as it is climate-controlled and protected from the elements. The building’s cladding and systems (electricity, plumbing, HVAC) can certainly wear out, but they can also be maintained indefinitely, and even updated, as long as the building owners can afford it.

Bill’s question’s appealing because it gives all of us license to become amateur futurists, but in a focused way. As we reported an answer for Bill, we heard that when you think about the future of tall buildings in cities, it’s useful to consider why we build very tall buildings in the first place.

In 1900, architect Cass Gilbert famously described a skyscraper as a “machine that makes the land pay.” While tall buildings are certainly impacted by demand for space, client or city image, it’s economics that truly drives the construction of skyscrapers. Developers seek to maximize the rent that a single parcel generates. Urban districts with expensive land tend to have tall buildings, because those buildings have more floors, more square feet, and therefore, more revenue potential.

But calculations about whether a particular skyscraper “makes the land pay” are deeply entwined with the fate of the building’s immediate neighborhood, and the city in general. The building, its neighborhood and its city — each can change, and so can the relationships between them.

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Written by Randy McDonald

December 21, 2016 at 9:30 pm

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