Green Roof Benefits

Environmental Benefits

Urban Heat Island Mitigation
The urban heat island effect is the temperature difference between urban areas and their rural surroundings. The temperature differential causes air currents and dust, and even contributes to violent weather events within urban settings. Green roof vegetation helps by cooling the air, slowing air movement and acting as a substrate for pollution to settle out and detoxify.

Noise Reduction
Plants, soil, and air trapped in the soil are great acoustic insulators. Tests indicate that green roofs can reduce indoor sound as much as 40 decibels, which is of great benefit to occupants of buildings affected by airports, industry, trains, and traffic.

Fire Prevention

Succulent green roof plants help reduce the risk of fire. See LiveRoof fire test… http://youtu.be/fee_jsP1w6I

Wind Uplift Considerations

LiveRoof modules populated with a base mixture of flexible-stemmed hardy sedums, were wind tested on 1/25/08 with wind speeds exceeding 110 mph.  Check out the LiveRoof video… https://www.youtube.com/watch?v=2XQWv0HRNDY

Water Conservation/Reduction of Storm water Runoff
The soil in green roof systems acts like a sponge and absorbs excess rain water. Research has shown that extensive green roof systems can reduce runoff by up to 90% annually (varies with climate, soil, and pitch of roof). Green roofs reduce the impact of each new building on the municipal storm drainage system and surrounding watershed. They reduce flooding, erosion and artificial heating of water which helps preserve fisheries and other aquatic life. Green roofs reduce the need for on-site storm water management systems and according to Seattle based Magnusson Klemencic Associates, under certain conditions, can offset the cost of a green roof by 30 to 60%. When combined with an effective rain garden (bioswale), green roofs can make it possible to have zero discharge of rainwater from the site, therefore saving money by not having to connect to the storm sewer system. Green roofs filter water prior to returning it to the aquifer. They buffer acid rain and remove nitrates and other contaminants as water slowly percolates through the soil. What runoff remains will usually occur hours after peak flows, providing additional time for sewer systems to handle the runoff burden from impervious surfaces.

Habitat Recreation
Plants and soil help recreate habitat for butterflies, insects, and songbirds.

Political Correctness
With an emphasis on recycled components, energy conservation, sustainability and reduced environmental impact (from development), green roofs score points with city planners, communities, and tenants. This is oftentimes rewarded with zoning that allows for more intensive development and higher selling and rental prices.

Conservation of Municipal Septic Systems
Sponging up excess rainwater means municipal septic systems do not have to be expanded as much. It also means reduced overflows as well as accompanying pollution and associated costs.

Extension of Roof Life
Plants and soil act as a protective shield from the elements.

This means:

• No U.V. radiation/photo degradation of underlying roofing components.
• Minimal thermal contraction and expansion (green roofs can reduce temperature fluctuations by as much as 90%). Studies show that on a sunny 95 degree day, conventional roof surfaces can reach 175 degrees. Green roofs bring these temperatures in line with ambient air temperature.
• Protection from drying winds.
• Protection from mechanical damage.
• Reduction or elimination of cracks and leaks.
• Potential 200% – 300% extension of membrane life expectancy.

Energy Conservation
The evapotranspiration effect of the plants and four inches of growing medium typically reduces indoor temperatures 6 to 8 degrees during warm/hot weather and can reduce air-conditioning costs 25 to 50 percent in a single story building. This not only allows for ongoing cost savings but an initial reduction in the size of the required air conditioning equipment.