France is requiring that new buildings “green” their roofs

French parliament approved a law last week that will force all rooftops of new buildings in commercial areas to be partially covered in either solar panels or plants.
Rooftop vegetation—otherwise known as green roofs—aren’t there to just look pretty. They reduce runoff by absorbing water, provide habitats for birds and other wildlife, and minimize the amount of energy buildings need to regulate temperatures. They also help to combat the “heat island” effect, in which cities become hotter than nearby rural areas, sometimes by as much as 22 degrees Fahrenheit (12 Celsius).
Despite the pleas of environmental lobbyists, the law won’t apply to rooftops outside commercial zones. It also won’t force existing buildings to be retrofitted with green technology.