Friday, October 26, 2007

Can A Green Roof Save You Money?

A green roof system is an extension of an existing roof which involves a high quality water proofing and root repelling system, a drainage system, filter cloth, and a lightweight growing medium and plants. Green roofs also involve “contained” green space on top of human-made structures. Although green roofs have been in used in Germany and other parts of Europe since the 1960s, the market remains immature in North America (besides in a few cities on the East Coast), as the benefits of green roofs have not been well-established.

Many green roofs are often installed to comply with local regulations and government fees, often regarding stormwater runoff management. In areas with combined sewer-stormwater systems, heavy storms can overload the waste water system and cause it to flood. Green roofs decrease the total amount of runoff and slow the rate of runoff from the roof. However, one of the greatest benefits of a green roof involves energy savings. In 2005, a study was conducted by the University of Toronto, which showed that green roofs also helped reduce heat loss and energy consumption in winter conditions. Green roofs can reduce heating by adding mass and thermal resistance value and cooling by evaporative cooling. This is especially true if the roof is glassed in so as to act as a terrarium and passive solar heat reservoir. Here are some other benefits of green roofs:

- Provide amenity space for building users and can replace a yard or patio
- Reduce the urban heat island effect
- Increase the roof life span
- Filter pollutants and CO2 out of the air
- Filter pollutants and heavy metals out of rainwater
- Increase wildlife habitat in build-up areas
- Retain rainwater, moderate the temperature of the water, and act as a natural filter for any of the water that happens to run off

To initiate a green roof installation, you will need to know the slope and structural building capacity, and nature of any drainage systems, electrical, and water supply. In terms of cost, for an installed, extensive green roof with root repellant/waterproof members, it will cost you anywhere from $10 to $24. However, this also depends on the type of roof you want and factors such as the depth of growing medium, selective plans, size of installation, use of irrigation, and whether they are accessible.


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