Costa Rica

Finca Bellavista is a development on the southern coast of Costa Rica with 5 houses and 24 other buildings, all sustainable treehouse structures.

Popular Science gives a brief intro to nine cities that are setting the bar for the reduction of carbon emissions. The best U.S. site? The fortuitously-named Greensburg, Kansas.

The New Economics Foundation's "Happy Planet Index" shows that Costa Ricans use fewer resources and lead happier lives than the rest of the world.