The Atlantic article, “Cities Really Can Be Both Denser and Greener,” quotes Director of Urban Expansion, Solly Angel:
By stacking urban residents one atop the other, land is spared for parks, trees, and gardens. That, he says, is Singapore’s real secret, not its green roofs. ‘In order to have more open space, you have to make it possible to build higher,’ Angel said. "That’s the main way of removing that conflict."