flexible roof structure; but results in lower vegetation density as it requires plants that are suitable for thin soil such as sedums. Extensive green roofing system can typically tolerate extreme moisture. Intensive green roofing structures consist of over six inches of soil. As a result, they can support greater plant diversity, but require elaborate drainage and irrigation systems and significant support structures for all the added weight.
The Benefits of Green Roofs
In large cities, green roofs can alleviate some of the environmental impacts of urbanization including reduction of the “Heat Island” effect. Concrete and asphalt have properties that cause them to retain radiant heat. Natural green vegetation does not have these same properties and is more effective at dissipating heat. The greater the building density, the greater the head absorption. The shape and style of the roof also influences heat retention. Lower-sloped roofs, or flat roofs, have higher retention of solar energy versus highly-sloped roofs, which are more effective at reflecting heat. According to the LEED standard, one of the strategies to optimize energy for roofs, specifically those that are flat, involves the addition of greenery. In addition, plants, trees, and shrubs exchange greenhouse gases such as carbon dioxide into oxygen and help to clean the air of pollutants.
Native and adaptive vegetation on building rooftops also provides habitats for animals and insects. Green rooftops can sustain life that would have otherwise been displaced due to urbanization. It is truly magical to watch butterflies and critters enjoying a beautifully designed green roof.
Storm Water Management
With the density of developed land in highly-urbanized areas, many communities have the challenge of reducing the amount of storm water runoff. Stormwater runoff can have a significant impact on erosion, as well as filtering pollutants and suspended solids into the water supply. Green roofs help to alleviate storm water runoff by naturally holding back rushing waters and creating a natural filtration system.
Extended Roof Lifespan
Finally, a green roof can provide extra protection for the building’s roofing structure, from mechanical damage to ultraviolet radiation. Green roofs are much more preferable than conventional roofing structures as they are less likely to be replaced frequently.
Have you ever thought about a green roof for your home? How about a garden on your roof?