Notas del episodio
People built tall long before the skyscraper. The Great Pyramid of Giza stood 146 meters and held the height record for thousands of years, while Roman insulae reached 10 stories or more despite Emperor Augustus trying to cap them at around 20 to 25 meters, with the poorest tenants on the exhausting top floors. Families in 12th century Bologna raised 80 to 100 towers, some over 90 meters, Shibam in Yemen built over 500 mud brick tower houses of five to 11 stories against Bedouin attacks, and walled Edinburgh stacked buildings up to 14 stories. Load-bearing masonry hit its limit with Chicago's 16 story Monadnock Building in 1891, whose base walls were six feet thick.
Two inventions broke that limit. Elisha Otis introduced the safety elevator in 1857, flipping the top floor from cheapest to most desirable, and the steel skeleton, from the 1797 Ditherington Flax Mill to Oriel Chambers' curtain wall in 1864, culminated in William Le Baron Jenney's 10 story Home Insurance Building in 1885. When wind and elevator shafts capped steel frames around 40 stories, Bangladeshi American engineer Fazlur Rahman Khan moved the structure to the perimeter as a hollow tube. Today the debate centers on energy, density, and timber.
- Vanity height, where up to 30 percent of a supertall tower can be an uninhabitable spire built for records
- The trussed tube X bracing of Chicago's John Hancock Center and the nine bundled tubes of the Willis Tower that disrupt vortex shedding
- Sky lobbies and the double deck elevators of the Petronas Towers that save core space
- Elevators using 5 to 25 percent of a building's electricity, and the Empire State Building's LEED Gold retrofit
- Cross laminated timber plyscrapers weighing a quarter of concrete and cutting carbon by 60 to 75 percent