What motivates people to plant the surface area of an urban roof?
Steve Luoni, Director of the University of Arkansas Community Development Center, provides one compelling answer: to reduce water pollution. Says Luoni, “The storm runoff in the first hour of rainfall has the same pollution index as raw sewage.” (University of Arkansas Research Frontiers, Spring 2008. p. 21.)
Another big reason to move to green roofs is to manage heat transfer more efficiently. Because of the insulating properties of green roofing materials and plants, green roofs reduce the amount of heat transferred between the building and outside environment. This reduction in heat transfer conserves energy and reduces building maintenance costs
Now go to and study Green Roofs to learn more about green roofs. As you study this resource, think about answers to these questions and be prepared to discuss them in class:
- What motivated Europeans to be leaders in green roof technology? Why are Americans slower to adapt?
- If we think of the green roof as a “sandwich,” what are the three layers?
- Now that we know the three layers, explain the role of each.
- What data did the Pennsylvania researchers have to suggest to them the green roof might help manage heat transfer? What would be a next good step to complete the experiment that measures green roof success?
Follow up this exploration of green roofs by looking at the concept of urban heat islands. Urban heat islands increase energy costs of maintaining buildings. Study the following websites—text, images, and graphics—and be prepared to discuss them:
Think about these questions as you study the images:
- What conclusions can you draw from a comparison of the two enlarged Landsat images of New York City?
- The color distribution of this image correlates with temperature variance in New York City. Where does it look the hottest?
- What areas look the coolest?
- To what do you attribute the difference?
- What general principles about urban heat islands does it suggest? Construct a hypothesis about energy interactions and transfers.
- What information is NOT on this graphic that would be helpful in making a scientific summary of the problem?
This esheet is a part of the Green Roof Design lesson.