In many ways, skyscrapers came to define the 20th century. Rising out of skeletons of steel, iron, and glass, they showed a new landscape and ecosystem to the world. Cities become incomplete without their own, and some like Hong Kong or New York City have gone full in on buildings 150 feet or taller, with 355 and 280, respectively.

But as climate change defines the 21st century, skyscrapers are among the first targets that urban developer would want to adjust. It's easy to see why: they take up a tremendous amount of resources.

“With today’s technology, a tower will always be more energy-hungry,” said Philippe Honnorat, head of building services at the consultancy WSP in the UK said in 2013. “If you’re going to wash or take a shower on the 80th floor, you have to bring the water up there. When you take your shopping up to your apartment in an elevator, that will consume more energy than if you lived on the ground floor.”

The challenge, Honnrat said at the time, is that while a one-to-one comparison with a skyscraper is dirtier than a smaller building, a city filled with them might have an advantage.

“In Manhattan, most people don’t even own cars, whereas LA has lots of low-rise, low-energy buildings that can only be reached by car, and require extensive energy and water infrastructure. On a building-by-building basis, it’s a no-brainer that towers use more energy.”

Here some buildings, some iconic and some brand new, pointing the way to a more sustainable future. They've earned their green status through the Leadership in Energy and Environmental Design (LEED) accreditation program, which is overseen by the non-profit U.S. Green Building Council (USGBC).