This article by Katrin Scholz-Barth provides a solid introduction to green roofs, covering a wide range of topics. The article explains the differences between intensive and extensive green roofs; discusses construction materials, maintenance requirements, and the requirements for roof load reserves and slope; describes their applications including stormwater management and enhancing energy efficiency; and provides information on cost and funding sources. The bibliography contains additional green roof references.

More information is available on North Carolina State University's Biological & Agricultural Engineering Greenroof Research page.

Partial abstract: Two extensive greenroofs have been constructed within the Neuse River Basin of North Carolina. Each greenroof retained approximately 60% of the total recorded rainfall during a nine-month observation period. The average peak flow reduction for both greenroofs was approximately 85%. Water quality data indicated higher concentrations of TN and TP were present in the greenroof runoff than in the control roof runoff and in the rainfall at each greenroof site. This may be a result of N and P leaching from the soil media; the soil media is composed of 15% compost. Preliminary results from a soil column test of three different greenroof soil medias indicate that leaching can be reduced with less organic matter present in the soil media. Vegetation growth observed after the first year showed growth was significantly higher (a <0.05) in 100 mm (4 in.) deep soil media than in 50 mm (2 in.) deep soil media.

This website presents findings for green roof plant growth and spread (a series of photos is shown) and for stormwater quantity reductions. Data from one storm shows that on the green roofs, 67% of rainfall was converted to runoff and 33% was retained. On the conventional roofs, 89% of rainfall was converted to runoff and 11% was retained. The site also describes the test roofs at the Penn State Center for Green Roof Research and mentions other ongoing research topics.

On August 9, 2001, at 1:45 pm, instruments recorded an approximately 50°F difference in the surface temperature between the green roof and an adjacent conventional roof. This website provides a small amount of temperature data as well as information on design, construction, and plant selection.

This report provides a comprehensive review of the quantitative and qualitative benefits of green roof and vertical garden technologies and argues that most of these benefits are not represented in the current market. The major barriers to the more rapid diffusion of these "sustainable development" technologies are described and a number of initiatives are proposed to encourage the development of Canadian markets, including government policy and program support. A summary in HTML is also available.

This website gives a brief discussion of green roofs and their growing popularity and provides a link to the audio archive of the story on NPR's Morning Edition. The bottom of the page contains links to other NPR green roof stories and online resources.

This article discusses the summer 2004 installation of Washington, D.C.'s first green roof on a downtown commercial property.