Benefits of a Greenroof

Prominent Public Benefits

Stormwater Management

Stormwater runoff is the term used to identify the movement of water over land surfaces during a rain event. Runoff is a serious concern in urban areas where the increase of impervious areas, like roads parking lots and buildings cause an increase in the speed and amount of runoff. This environmental impact weighs heavily on the waterways creating erosion and pollution. Stormwater runoff is also detrimental to city trees. The speed of the water during a rain event does not allow the water to properly soak into the ground, resulting in depletion of city trees.

Rooftops are the first point of contact for rain. They are traditionally made of impervious materials. In contrast, greenroofs retain water and provide a viable solution for runoff management. This is especially so in urban areas where rooftops comprise a large surface area. Geenroofs retain and delay water that enter the sewer system. In addition, rainwater filtered by greenroofs is less acidic and has lower nitrate levels.

Urban Heat Island Reduction

Urban Heat Island (UHI) describes the increase in overall city temperature due to the materials that dominate the typical urban landscape. Dark surfaces such as asphalt and tar retain heat and increase ambient air temperatures. Increasing loss of tree cover also contributes to UHI. The impact of UHI has the potential to be a serious health concern for urban dwellers as cities continue to get hotter. Heat also significantly increases energy consumption. Utilities and other machines work harder creating more air pollution.

Vegetation is how the earth balances the power of the sun. As cities grow, green space disappears. Greenroofs do two things to decrease UHI: (1) cover the heat absorbing materials that many city rooftops are made of and (2) add green space to the city even as the footprint of a city grows. The functionality of greenroofs is important to UHI reduction. Studies have shown that greenroof coverage can significantly lower city temperatures.

Secondary Public Benefits: