vanity height

(名詞) 無用的高度 - 高樓或超高建築由尖頂或類似增建部分所產生的沒有用的空間。尖頂或類似增建部分只是在增加建築物額外的高度而已。

Some of the world's tallest skyscrapers have been criticised for being built with added "vanity height", which serves no practical purpose other than to push them into the architectural category of "supertall".
—Oscar Quine, "The height of vanity: Why taller isn't better and the 10 vainest buildings in the world," The Independent, September 9, 2013

Dubai's Burj Khalifa — currently the world's tallest building at 2,717 feet — is topped by 800 feet of unusable ornamentation. That means almost 30 percent of the world's tallest building is "vanity height."
—"Editorial: 'America's tallest building' goes to New York," Chicago Tribune, November 13, 2013