60 Second Seminar Session 5: Green Roofs
Each brief educational session is designed to provide concise, interesting, informative insights on a variety of topics in just 60 seconds. You will be surprised at how much you can learn with only 60 seconds of your time!
Did you know that the first vegetated green roofs date back to 500 BC? The Hanging Gardens of Babylon were considered one of the Seven Wonders of the World. Modern green roof design has its “roots” in Germany in the 1960’s. In fact, green roofs are much more common in Europe than they are in the US but every year they are gaining in popularity. The trend is here to stay and growing fast!
Ferdinand Knab (1834-1902), Hanging Gardens of Babylon by Ferdinand Knab (1886), marked as public domain, more details on Wikimedia Commons
Aside from the aesthetic beauty of a vegetated roof, there are many other important benefits. When people see a green roof they often exclaim “That is so cool!”. And, quite literally, a green roof cools down a roof by 30 – 40% and can reduce air conditioning costs in a building by up to 75%, according to the National Research Council of Canada.
Benefits of a Green Roof:
- Reduce stormwater runoff by up to 65%. In urban areas, this makes a huge difference!
- Reduce “heat flux” from the roof of a building up to 72%. Heat flux, also called thermal flux, is the rate of heat energy flowing per unit area.
- Green roofs attract birds, bees, and insects which is especially helpful in a city where it enhances “biodiversity”.
- The extra layer of insulation absorbs up to 30% of environmental pollution noise.
- Protects the roof membrane which at least doubles the life of the roof.
- Reduces urban heat island effect.
- When planted, the roof has a beautiful and natural look.
Unlike the original green roofs of ancient times, green roofs today are made to last up to 50 years. All designs include a waterproof membrane and sometimes a root barrier, drainage layer, and irrigation system. Some green roofs even allow for collection of excess water in a cistern that can be used later!
Cell-Tek’s LSG Series® Load Support Grid, and SlopeGrid® are often used to contain soils and keep them in place, especially on a sloped roof. The cells are filled with dirt and planted with vegetation. To secure the grid to the roof, cables or tendons are strung through the grid, much like the cords in a venetian blind, and then they are tethered to the perimeter of the roof. LSG Series® and SlopeGrid® are available in 4” or 6” cell depths, the 4” cell is commonly used for this application.
The below photos were provided by Columbia Green Technologies.
Columbia Green Technologies is a leader in Green Roof design with their innovative green roof technology.
This project for Five Rivers Environmental Education Center in New York used LSG Series® grid on the sloped areas of the roof.
Click here to see drone footage of the completed Five Rivers Environmental Educational Center green roof.
These products are available through Cell-Tek Geosynthetics or your local dealer.
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