Environmental Benefits of Green Roofs

Reduce Storm-Water Runoff

• Conventional roofs, in conjunction with roads, parking lots and other impervious surfaces, have created a huge negative impact on our environment. These surfaces prevent rainwater and melted snow from being naturally absorbed by the earth. Instead, this water sits on the surfaces of roofs and pavement and drains into storm sewer systems, which carry it to rivers, lakes and other bodies of water. This water is contaminated with oil, solvents, litter and other pollutants that it collects on its way there. A major benefit of green roofs is their ability to absorb some of that water before it contributes to storm water runoff. The vegetation and roof system mimic the natural process of absorption and evaporation.

Pollution Filtration and Absorption

• Green roofs, just like natural vegetation, filter water and air of pollutants. Airborne toxins, such as carbon dioxide, are absorbed by the vegetation. The heavy metals that are found in rainwater are filtered out naturally by vegetation, which prevents it from being distributed to the water sources.

Create Habitat

• A green roof can help restore some of the habitat that birds, bees and butterflies have lost because of construction. According to the London Ecology Unit, butterflies will visit gardens up to 20 stories high. If proper native vegetation is used, green roofs can provide micro-habitats for species forced out of their homes.

Reduce Heat Island Effect

• The "heat island effect" occurs in cities as a result of the built-up environment. The buildings and pavement lead to an unnatural increased temperature in the area. This leads to problems such as increased energy consumption, impaired water quality and heath issues among people. Conventional roofs act as reflectors and divert the heat of the sun out into the surrounding area, but green roofs absorb the heat just as natural vegetation would.

Stabilize Temperature

• A green roof reduces the need to heat and cool a building. This roof system has a dramatically improved thermal resistance compared with a conventional roof system, which helps to prevent heat from moving through the roof. This translates into money and energy savings because the internal temperature is stabilized by the green roof.