Green Roofs - Science Nation

These days it seems everything is going green. Now you can add green roofs to that list. A green roof is covered with a waterproof membrane, a growing medium (such as dirt) and vegetation. Environmentalists have long touted the benefits of green roofs, which they say include minimizing storm water runoff, cooling the environment, and helping to absorb CO2. Local governments have been paying attention to the claims. In New York, if you have a green roof you are eligible for a tax credit. But no one has ever done a scientific environmental analysis of green roofs... until now. With funding from the National Science Foundation, Patricia Culligan of Columbia University is studying green roofs, from their effects on storm water runoff and CO2 absorption to claims they impact local climate and save energy.