The Year in Tall Buildings

The yearly study published by the Chicago-based association, available on their Skyscraper Center website, focuses on buildings reaching more than 200 meters. Doing so puts China, with 88 completions, well ahead of second-place United States, which had only 13 completions. Accordingly, three-quarters of all 200-meter-plus towers completed last year were built in Asia. The only non-Asian city to be included in the top 18 of completions is New York City, with 8 towers; by comparison, Shenzhen, China, had the most with 14 towers. Other statistics in the report look at the functions of towers (evenly split between office, residential, and mixed-use/hotel), trends in height and other criteria over time, and the materials that towers over 200 meters are built from.

The material statistics are particularly revealing, especially when seen across time. As the chart below shows, composite structures are increasing, while all-steel towers are continuing to decrease. More than half of all completed towers in 2018 (not just 200-meters-plus) are composite structures. Though the reasons behind this increase aren't spelled out in the report, composite structures enable taller heights through such tactics as "megacolumns" of steel encased in concrete, for instance, while also allowing improved structural performance, speedier construction, and related cost reductions. Regardless of these benefits, the continued reliance upon concrete (87 percent of completed towers last year used concrete by itself or with steel) in tall building construction does not bode well for climate change, given that the material is responsible for nearly 10 percent of all CO2 emissions.