Cooling green roofs seemed like an impossible dream for Brazil's favelas. Not true!

Cooling green roofs seemed like an impossible dream for Brazil's favelas. Not true!

It was a sunny September morning in Rio de Janeiro’s Parque Arará favela and volunteers were preparing plants to be placed on Reginaldo Gomes da Silva’s roof.Students from both the neighborhood elementary school and nearby federal university helped roll up Spanish moss, kalanchoe and other tropical succulents in bidim, a lightweight polyester geotextile made of recycled drink bottles. They tied the small bundles with string and passed them to th…