green_roof.jpg
Figure 1: A city building with a green roof


Table of Contents
Overview
Environmental Benefits
Financial Benefits
Miscellaneous Facts
Glossary
Quiz
References




Overview
A green roof is a roof that is partially or completely covered with vegetation.1
Green roofs have many beneficial purposes. These include the growing of plants and vegetation, which can be then either used for decoration or can be used as a food source if edible vegetation is grown. These roofs also provide insulation and even new habitats for animals. The are two main types of green roofs, extensive and intensive. Extensive roofs are shallow and used for just the purpose of being ecologically friendly (they are thinner and less aesthetically pleasing), whereas intensive roofs have flowers and vegetables that can be grown and they also look better.1 They can be implemented in any setting, urban or rural as seen in figure 1. Green roofs are a great way to reduce the ecological footprint of any buildings that are created. These roofs are a great alternative energy reduction source and will continue to be used more commonly in the future. Many eco-conscious cities have already got green roofs in place.2

Environmental Benefits
Green roofs benefit internal heating systems like furnaces because of their insulation value and therefore reduce the energy needed to heat the building. These roofs create an increased agricultural area for growing of plants. They also reduce the pollutants in rainwater as it falls and is absorbed on the roof. Green roofs also drastically improve air quality.1


green roof layers.jpg
Figure 2

As you can see in figure 2, the individual layers of a green roof each have their own specific purpose. Each helps the environment in its own way.

Financial Benefits
Green roofs are also very rewarding financially, especially in the long term. They can increase the actual roof's lifespan, it raises the real estate value of the property, it reduces the amount of energy needed in any building that has a green roof, and even has federal and local tax incentives.1

Miscellaneous Facts
On a hot and sunny day, an asphalt roof is 158 degrees fahrenheit, a white PVC roof is 101 degrees fahrenheit, but a green roof can be 30-60 degrees cooler than that. This can in turn help with energy costs in hot weather.1
Green roofs improve air quality and help reduce the Urban Heat Island Effect.3



For a general information summary of green roofs, please watch this video for further understanding.
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Glossary

  • Urban Heat Island Effect, the absorption and retention of heat in urban areas compared to the surrounding rural areas.

Quiz
  1. Name one ecological and one financial benefit of green roofs.
  2. Define the Urban Heat Island Effect, a condition that green roofs help prevent.
  3. Name the 2 different types of green roofs.
  4. Name two things a green roof does better than any other type of roof.

References
  1. Green Roof Benefits. [Homepage on the Internet]. 2012 [Cited 2012 June 17]. Available from: http://www.greenroofs.org/index.php/about-green-roofs/2577-aboutgrnroofs
  2. City of Toronto: Green Roofs. [Homepage on the Internet]. 2012 [Cited 2012 June 17]. Available from: http://www.toronto.ca/greenroofs/
  3. Heat Island Effect. [Homepage on the Internet]. 2011 [Cited 2012 June 17]. Available from: http://www.epa.gov/hiri/mitigation/greenroofs.htm
  4. Green Roofs 101. [Homepage on the Internet]. 2009 [Cited 2012 June 17]. Available from: http://www.youtube.com/watch?v=pp79mGpomf4