The primary ecological benefits of Green Roofs are as follows:
- The Reduction of Urban Heat Island Effect. An urban heat island (UHI) is a metropolitan area which is significantly warmer than its surroundings. As population centers grow in size from village to town to city, they tend to have a corresponding increase in average temperature, which is more often welcome in winter months than in the summertime Not to be confused with global warming, scientists call this phenomenon the “urban heat island effect”. Heat islands form as vegetation is replaced by asphalt and concrete for roads, buildings, and other structures necessary to accommodate growing populations. These surfaces absorb – rather than reflect – the sun`s heat, causing surface temperatures and overall ambient temperatures to rise.
- Natural Storm Water Management. Green roofs can reduce the volume of storm water run-off, delay peak discharge, extend the roof lifecycle, and cool and filter the run-off compared with a conventional roof.(Roofing Contractor Magazine, Apr 2007)
- Provide Insect and Bird Habitats
- Filter Airborn Pollutants
- Provide a Positive Image for Ecological Design, replicating some of the natrual systems and processes that would otherwise be lost in creating a building. Green roofs provide a way for buildings to demonstrate ecological responsibility in a tactile, understandable way to building visitors and occupants.(Roofing Contractor Magazine, Apr 2007)
- Durability. Green Roofs typically last longer than conventional ones. A conventional roof might last 20 years, while a green roof will survive 40 to 50 years. That`s because the plants and soil protect the waterproofing from ultraviolet rays and temperature fluctuations that cause cracks.(Waterproof magazine, winter 2008)
- Energy Efficiency and Acoustical Comfort. The soil and plants on a green roof add insulation, increase energy efficiency, and absorb sound. Field studies in Ottawa, Canada, found that a 6-inch-thick green roof reduced heat gains by 95% and heat losses by 26%
- Occupant Well Being. Studies in Europe show that workers in green offices are happier, more productive, absent less often, and stay with the compnay longer. The building owners, in turn, are able to charge more for space.(Waterproof magazine, winter 2008)
Source:: All American Exterior Solutions
As a Brooklyn green roof installer we are always asked about the benefits of a green roof. I found this list of benefits to be very helpful. It is clear, honest and concise.
Here is the green roof on our Brooklyn Green Show House. It is in it’s first year so isn’t fully grown out but as you can see it is still beautiful and fulfilling all the benefits listed above. It has a mix of fragrant flowers, edibles, herbs and butterfly/bee/hummingbird friendly plants. The bee hives are in the background. The deck is all salvaged.