P&PDL Picture of the Week for
November 11, 2013

Hidden in plain sight? Green roofs in big cities

Kyle Daniel, Commercial Nursery and Landscape Outreach Specialist, Department of Horticulture and Landscape Architecture, Purdue University

When travelling, the first place I go once in the hotel room is the window. In many hotels, especially in large cities, one can get a ‘bird’s eye view’ of the city. When walking around the sidewalk it is impossible to know what sits atop of the buildings. Until several years ago there was not much that was worth seeing, unless you were an engineer or architect, as air conditioning units, pipes, and furnaces were all too common. That is quickly beginning to change.

On a recent trip to Chicago, as I looked out of the window, instead of an air conditioner, I saw a ‘living’ roof. While I realize that many nurseries, including some Indiana nurseries via contract, are growing selected plants for green roofs, i.e. cold-hardy succulents, I still don’t anticipate ‘seeing green’ on rooftops. It is a great trend for my fellow horticulturalists, as well as those with concerns for the environment.

Many European countries have embraced green roofs, so after many years of exponential growth, this industry has matured. In the United States, green roofs are, commercially, relatively young. This is a trend that holds promise for the many benefits of green roofs, not to mention the economical impacts to the nursery and landscape industries.

According to the organization Green Roofs for Healthy Cities, there are many benefits, both environmental and monetary. These include:

  • Reduction in storm water
  • Moderation of ‘heat island’ effect of most large cities
  • Improvement of air quality
  • Aesthetics and green space for tenants
  • More efficient energy usage
  • Noise reduction
  • Biodiversity improvements

Two trends in the United States include movement back to city centers from suburbs and rural areas and an intense focus on sustainability and environmental concerns. These two trends are the main drivers to installations of green roofs. Green roofs, for the reasons listed above, will most likely begin to also involve food production via rooftops. Food production on rooftops will be more sustainable, as local foods can be produced for restaurants and home refrigerators. Green roofs hold much promise in large cities, and I hope to continue seeing more out of my windows in the coming years.

To learn more about green roofs, please visit www.greenroofs.org

Click image to enlarge

Green roof on Chicago building

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service