|Green roof on Battle Creek's public safety building|
|Expansive green roof on the Ford Rouge Plant in Dearborn, Michigan|
Green roofs are a strategy used to capture the stormwater runoff from commercial, industrial and residential buildings. In contrast to traditional asphalt or metal roofing, green roofs absorb, store, and later evapotranspire initial precipitation, thereby acting as a stormwater management system and reducing overall peak flow discharge to a storm sewer system. Furthermore, conventional roofing can act as a source for numerous toxic pollutants including lead, zinc, pyrene, and chrysene. Green Roofs not only allows for a more aesthetically pleasing feature but acts as a friend to the environment but slowly releasing clean water into storm drains.
- Green roofs offer benefits including reduction of urban heat island effects
- Increased thermal insulation and energy efficiency
- Increased acoustic insulation
- Increased durability
- Extending the life of a roof (2 to 3 times more than a conventional roof)
- Providing aesthetic improvments in urban areas
- Improved air quality
- Conserving valuable land that would otherwise be required for stormwater runoff controls
URBAN HEAT ISLAND EFFECT
An additional benefit to urban cities is the reduction of urban heat. The buildings, concrete, asphalt, and the human and industrial activity of urban areas have caused cities to maintain higher temperatures than their surrounding countryside. This increased heat is known as an urban heat island. The air in an urban heat island can be as much as 20°F (11°C) higher than rural areas surrounding the city.
The increased heat of our cities increases discomfort for everyone, requires an increase in the amount of energy used for cooling purposes, and increases pollution. Each city's urban heat island varies based on the city structure and thus the range of temperatures within the island vary as well. Parks and greenbelts reduce temperatures while the Central Business District (CBD), commercial areas, and even suburban housing tracts are areas of warmer temperatures. Every house, building, and road changes the microclimate around it, contributing to the urban heat islands of our cities.
Europeans, led by the Germans, have been using green roofs for decades and have found them to be a cost effective method to mitigate some environmental impacts of development.
DID YOU KNOW...
One inch of rain on a 1,000 square-foot roof yields approximately 623 gallons of water!