Many of our homes, buildings, roads and sidewalks are virtually waterproof - scientists believe that together, these "impervious surfaces" would cover all of France with ease! Pollutants build up on impervious surfaces until rainwater washes them into waterways, where they can harm sensitive habitats. Once in these ecosystems, pollutants like nitrogen and phosphorus can generate harmful algal blooms that block life-giving sunlight, suck up oxygen and sometimes release toxins that sicken or even kill aquatic wildlife. Luckily, there are some solutions to this problem, and one example is called a "green roof." By blanketing a rooftop with vegetation, the plants and soils will trap, absorb and clean rainwater before it runs off into the environment.
Viewer Tip: In addition to managing stormwater, green roofs can benefit your home in many other ways, including improving the overall appearance of your home. Green roofs can:
- Reduce your energy costs - green roofs insulate buildings by absorbing heat and that reduces the amount of energy your home needs to maintain a comfortable temperature.
- Reduce the heat island effect - in the dog days of summer, rooftop temperatures can be up to 90 degrees Fahrenheit hotter than the actual air temperature. That means that on a 95 degree day, your rooftop could be as hot as 185°F! If you've installed a green roof, not only will its temperature be lower, but it may be even cooler than the air around it!
(Sources: Elvidge, Christopher D., 2007. “Global Distribution and Density of Constructed Impervious Surfaces.” Sensors: 7, 1962-1979; U.S. Environmental Protection Agency. “Green Roofs.” Accessed Online May 22, 2012. Image courtesy of the USDA.)