Low-income favelas would benefit from green roofs but there are two problems: Cost. And a typical design that's too heavy for ...

yellow and purple plants sprouting from their dirt. Luis Cassiano outside his green-roofed home in Rio de Janeiro. He's the founder of a nonprofit group that promotes green roofs. Ian Cheibub for ...

yellow and purple plants sprouting from their dirt. Luis Cassiano outside his green-roofed home in Rio de Janeiro. He's the founder of a nonprofit group that promotes green roofs. In Gomes da ...