For 30 years, Stephen Keane, 78, saw the same thing outside his apartment windows: a dark, plain roof adorned with some tired-looking air-conditioning units. Today, he looks out those same windows and sees a quilt of creeping plants with burgundy flowers. That old eyesore of a roof was transformed in September into a thriving “green roof.”
“It’s kind of relaxing to look out this window,” he says while viewing the lower roof that covers the retail space in his apartment building, 1841 Columbia Road (1841 Columbia Road NW; 202-234-4619). “It looks like it’s spruced up a bit.”
Like a growing (no pun intended) number of roofs in the D.C. area, this one has gone green. In fact, for the past two years, the Washington metro area has installed the most green roofs of any metro area in North America — 1,326,872 square feet in 2012 alone — according to the nonprofit Green Roofs for Healthy Cities. Apartment building owners are putting down roots on their roofs for a variety of reasons, including local government rebate programs and providing residents with landscaped, environmentally friendly rooftop terraces.
Part of a green roof’s appeal is that it has more layers of protection than a traditional roof. On a green roof, the usual layer of waterproof sheeting is topped with 3 to 12 inches of a lightweight soil mixture that makes a bed for plants, typically low-growing varieties of “sedum” — hardy plants that require little watering.
In addition to providing protection from the elements, green roofs also absorb rainwater, a concept critically needed in urban areas, including the Washington region, says Nancy Somerville, executive vice president and CEO of the American Society of Landscape Architects, which has a demonstration green roof on its headquarters (636 I St. NW; 202-898-2444).
This region has what’s called a “combined sewer system.” During heavy rains, the system can overflow, Somerville says, which “leads to a release of completely untreated sewage” into the Potomac and Anacostia rivers.
“Yeah,” she says. “A big ick.”
The preventive perks of green roofs don’t stop there. Tests have shown that the surface of green roofs can become cooler than the air, while the surface of traditional roofs can increase up to 90 degrees above it, according to a report by the Environmental Protection Agency.
Because of this, Keane and his neighbors who live on the inside of the U-shaped building and overlook the lower roof could theoretically feel cooler next summer. Then they won’t have to crank up the air conditioning so high.
After paying electricity bills greater than $200 a month in their Victorian English basement in the District, Joe Mosimann, 29, and Kelsey Nepote, 26, went on a hunt for a more energy-efficient abode.
They moved into a similar-sized one-bedroom in The Asher apartments (620 N. Fayette St., Alexandria; 888-273-7048) in March. In addition to having green roofs on the fourth-, fifth- and sixth-floor terraces, the building also has solar panels on the very top.
They now pay $70 a month for electricity.
Not only do they have more money in their pockets, but they also have three parklike roof terraces where they can grill.
And when birds drop seeds among the sedum, and uninvited plants start to grow, it’s the apartment building’s problem to weed out the invaders.
“Luckily, our green roof is maintenance free for us,” Mosimann says.
Green for Green
In efforts to reduce the amount of rainwater going into the sewer system, local municipalities including the District, Arlington County and Montgomery County, Md., are encouraging developers to lay down green roofs by offering rebate programs up to $10 a square foot. UIP Property Management took advantage of such a program and received a rebate of $7 per square foot for the new roof on 1841 Columbia Road. It’s a win/win for everyone, says UIP CEO Steve Schat: “It looks pretty, it’s good for the environment, and it makes the apartments around it more livable.”