CITY HALL GREEN ROOF

Chicago, Illinois

The roof was installed in 2000 as part of the City's Urban Heat Island Initiative which tests the benefits of green roofs and how they impact temperature and air quality. This building is one block wide and twelve stories tall with a lot of roof area: a perfect candidate for this experiment. This intensive roof has approximately 20,000 plants, including shrubs, vines, and two trees. The program was successful, as the roof not only reduced the City's Urban Heat Island effect, but it also created a bunch of other benefits. One of these benefits was that the vegetation retained 75% of a 1-inch rainfall before there was stormwater runoff into the sewers.