Green Roofs – My Ah-Ha Moment


Standing with Barbara Deutsch on the green roof at Casey Trees here in Washington, DC, I had my ah-ha moment. Now, Gary has done a great job of explaining what a green roof is and how it works, but I needed to experience one for myself. So we went on a green roof mini-tour visiting Casey Trees as well as the green roof at the American Society for Landscape Architects (ASLA). At Casey Trees, the roof was green, or at least brown-green, covered with sedum plants that cool the building, extend the life of the roof and reduce polluted stormwater runoff.

“Just look at all these other roofs,” said Barbara pointing out toward the buildings surrounding McPherson Square. “All of that prime rooftop real estate is just wasted space.”

Wow. A whole new perspective, the bird’s-eye view of real estate. We’re wasting a whole dimension of our cities by leaving rooftops flat and devoid of life. If every building had a green roof, cities would be greener, more attractive, and cooler. In fact, Casey Trees and Limno Tech (pdf) found that if 80% of eligible rooftops in DC had green roofs combined sewer overflows to the Anacostia and Potomac Rivers would be reduced by 15% and air pollutants reduced by almost 17 tons.

So with all these benefits the real question is – why aren’t we doing this all the time to increase the effective green infrastructure of our communities? The usual barriers exist, like lack of familiarity, although that’s waning and there is now quite a green roof industry in the U.S.

But what are the best ways to institutionalize green roof techniques so they are the norm for all new construction and roof replacement. Ideas, anyone?