Cities are facing climate change. Urban areas are warming up. Storm water overflow is contaminating beaches, bays, rivers and lakes. Development continues to encroach on the natural environment.
Green roofs (or “eco-roofs”) provide a simple, practical solution to all these problems. Green roofs are an engineered, lightweight roofing system that supports plants. Green roof technology has been popular in Europe for 30 years, and is used in some North American cities including New York, Chicago, Toronto, and Portland, Oregon. But green roof technology is not well known in most of the United States and hardly at all in San Diego.
I planted San Diego’s first occupied commercial green roof at my own business in Kearny Mesa this past March. Green roofs offer a number of benefits both to the environment, and to the businesses and residences that install them. Green roofs can prevent water pollution, lower energy use, lower ambient air temperatures, combating the urban heat island effect, clean the air and add oxygen, mitigate the loss of environment, and extend the lifespan of the roof by two or three times.
Perhaps the biggest benefit to avid gardeners is that green roofs provide found space, a place to garden where none previously existed, especially in urban environments.
Why can’t we bring this technology to San Diego and the Western United States and make green roofs successful here? While you might think San Diego provides a perfect environment, our lack of rainfall means we have the challenge of successfully establishing a green roof in an arid region while mitigating the need for excessive irrigation.
So I’m doing in the hard way, with Southern California native plants for lower water use and maximum environmental benefits. They are planted in 20 yards of custom blended growth media which is spread across the roof to a depth of four inches.
The cost of an installed green roof is approximately $10 to $25 per square foot. Ours cost roughly $24,000, including a new roof (which was about half the cost). While green roofs typically require a greater initial investment, it is important to keep in mind that they can extend the life of the roof by decades and reduce the heating and cooling costs of your building.
But the real bottom line is this: we have to start getting serious about ways to improve our environment and reverse some of the damage we’ve done. When you have children like I do, you start thinking about what we’re going to leave behind for the next generation. A lot of people talk about it. I’m committed to creating public policy changes that will drive the market for green roof technology in the western United States.
— JIM MUMFORD