Chicago currently has 400 green roof projects in various stages of development that will total nearly 4 million square feet when built, more than the rest of the country combined.
Being one of the largest cities in the U.S, Chicago has been working on making its city sustainable over the years. One of the policies they are trying to spread through the city is in decreasing the urban heat island affect by building more green roof gardens. The urban heat island effect is caused by the tendency of hard, dark surfaces, such as roofs and pavement, to be measurably hotter than natural areas. It can raise a city’s temperatures 4 to 10 degrees Fahrenheit on hot summer days. One key example of the city is in 2001 chicago established a 21,000 square feet green roof on top of City Hall, which helped decease the urban heat island effect. Adjacent to City Hall is the Cook County building with asphalt rood that is 70 degrees hotter on a 95-degree day.
A program that has been implemented to encourage businesses and large buildings to incorporate these green roofs is through the Green Roof Improvement Fund. This is a 50 percent grant match for the cost of placing a green roof on an existing building located in the Central Loop TIF District up to a maximum grant amount of $100,000 per project. The Green Roof Grant program awards $5,000 grants for green roof projects on residential and small commercial projects (City of Chicago). These programs are created to be a small transition into making it feasible for buildings to be able to afford these green roofs. This policy hope to encourage better cooling in the case of high temperatures, but is also cost-effective since less energy will be used.
Apart from the fact that it will reduce heat, it can also be used to retain rainwater. The increase of this policy may have a shift in the eco-system in urban areas. In the article Meausring Urban Sustainability, Marina Alberti states, “A final criteria that characterizes a sustainable city is its ability to leans and modify its behavior- both at the community and individual level in response to environmental change (Alberti 389)”. Unfortunately, there seems to be a lack of understanding of green roof technologies in North America. According to the Green Roof for Healthy Cities website, “North America, the benefits of green roof technologies are poorly understood and the market remains immature, despite the efforts of several industry leaders. In Europe however, these technologies have become very well established. This has been the direct result of government legislative and financial support, at both the state and municipal level. Such support recognizes the many tangible and intangible public benefits of green roofs”(Green Roofs).
Alberti, Marina. Measuring Urban Sustainability. Center for Conservation biology, Stanford University