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The Future of Green Roofs in the United States

In Europe the green roof industry has continued to grow each year for the past several decades. In Germany, it is estimated 12% of all flat-roofed buildings are covered with vegetation, a number that is increasing as the German green roof industry continues to grow 10 to 15% per year. While the green roof industry in the United States maintains a steady growth rate, the industry is still young with many areas needing advancement. Several of the barriers to green roof expansion in the U.S. include: limited performance standards, lack of awareness and education regarding green roofs, higher installation costs, lack of favorable government policies, and limited data quantifying green roof benefits. These barriers can be easily overcome through research and innovation in design by the green roof industry.

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Scientific research is needed to expand our knowledge base to help guide future urban design, development, and management. Much of the early green roof research pertained to architecture and engineering problems.  The current trend seems to be in the direction of landscape ecology and biodiversity, possibly due to increasing interest in environmental issues.  In addition, since the majority of research has been conducted in temperate regions of Europe and North America, there is a lack of information from locales with tropical, sub-tropical, and arid climates. There is a need for interdisciplinary research among areas of plant and soil science, landscape architecture, fisheries and wildlife, ecology, architecture, engineering, economics, and public policy.

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Since roofs represent 21-26% of urban areas, they provide a unique opportunity to utilize these typically unused spaces to reclaim habitat that was lost due to construction while also aiding in the protecting of our environment through more sustainable practices.

Banner Photo:

Talinum calycinum in flower on Rowe doghouse (July 2005)

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Leading North American metropolitan regions for green roofs installed during 2011
(Green Roofs for Healthy Cities)

A grassy green roof with purple flowering plants.

The trend is more emphasis on biodiversity and landscape ecology such as the Aquascapes, Inc green roof in St. Charles, IL

A city bus outfitted with a green roof.

The Future??