Every year, billions of gallons of rainfall are deflected from buildings, parking lots, and other made-made surfaces into sewage systems, overwhelming municipal infrastructure and flooding oceans, rivers, and other bodies of water with contaminants and toxic chemicals. Over 25 million acres of impervious surfaces cover the United States alone, and more are popping up everyday.
To protect our dwindling water tables and endangered aquatic wildlife, cities across the globe are going to need a combination of higher-capacity sewage systems and a new way of thinking about runoff management.
Green roofing is one solution to drainage control that not only lessens the impact of water runoff on the environment, but also contributes to heating and cooling efficiencies. By covering rooftops with vegetation, rainwater can be filtered through root and soil systems before being used in rainwater harvesting reservoirs or being fed into sewage channels. Green roofs simultaneously mitigate heat island effects and help regulate building temperatures, bringing energy savings as well as a home for wildlife.
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To those who bemoan urban sprawl, green roofing also provides a unique opportunity to restore natural elements to the cityscape, and once-barren rooftops could easily be converted into thousands of aerial parks and meditative escapes above residences and businesses - add a few benches, some meandering walkways, and suddenly you've transformed unusable space into a unique zen garden with a stellar view.
As smart water management and building efficiency continue to climb in public importance, green roofing is an increasingly attractive design feature for today's LEED-seeking projects, and may soon be a regular retrofit feature. American Rivers, an environmental non-profit dedicated to restoring rivers and streams within the United States, has developed an online tool for calculating potential savings from green roof installation - which are substantial in most cases. With this and other public relation pitches, hopefully green roofing can attract the eye of prominent builders within the U.S. and abroad and help bring some literal greening to the global construction industry.