Sustainable Urban Design: Educator’s Toolkit for Project-Based Learning, page 20 of 20

Succulent plants on a green roof
Green roof on the American Society of Landscape Architects building in Washington, D.C. © Karine Aigner

Green Stormwater Infrastructure: Green Roofs

The Environmental Protection Agency defines a green roof as “a vegetative layer grown on a rooftop...They can be as simple as a 2-inch covering of hardy groundcover or as complex as a fully accessible park complete with trees.” A green roof can help cool a building, reducing energy costs. It also helps to manage stormwater by replacing an impermeable surface—a roof—with permeable soil and vegetation. In addition, a green roof can provide an accessible green space for school and community members.

While installing a green roof may not be realistic for your class or school, the process of studying and designing green roofs, and possibly building a model, can be valuable and can help students understand many green infrastructure topics. And you never know when their research and designs might help inform a green roof construction project in the future!

Get Started

You will likely need to consult an engineer to plan and install a green roof; however, there are several classroom activities that can lead you through the research and design phase with students. Consider building model green roofs on small tables or on the top of sheds or other minor buildings on your school's campus. By building models, students can experiment with a variety of roof slopes and other factors to determine which design works best.

Common Challenges

  • Getting permission from community government or school boards and maintenance staff.
  • The building must be built or reinforced to bear the weight of the soil and vegetation.
  • Like any garden, the vegetation will need to be maintained and watered during the summer when school is not in
  • session.

Maintenance Schedule and Other Notes

  • Watering typically needs to take place during the summer (when the students are not in school).
  • Weeding at least 3 or 4 times a year. Invasive species and woody plants that could puncture the waterproof membrane must be removed.
  • Plants may need to be cut back or replaced. A biannual assessment is recommended.
  • Adding mulch to the roof garden yearly.

Related Lessons and Classroom Integration

Additional Project Resources