Not long ago, spotting vegetation on the roof of a building in Cincinnati was a sure sign of urban decay. If a building was so neglected that plants were taking root in the dirt on its flat surfaces, one could reason, it wouldn't be long before wind, snow or a wrecking ball brought the roof down on the place.
But now, roofs are sprouting green throughout the city. And people aren't shaking their heads in dismay or calling in the demolition teams - in fact, they're praising the spread of a very visible, and often beautiful, environmentally conscious technology.
The new developments are green roofs: sections - or entire roofs - covered with what could be considered a very large container garden: a layer of soil anywhere from a few inches to nearly a foot thick, planted with grasses and other plants.
Green roofs and walls aren't exactly new technology. Humans have known about the insulating qualities of sod roofs and walls for millennia; soil is an excellent insulator, and the plants growing on a green structure help keep that soil in place with their network of roots. Semi-buried homes and buildings are somewhat rare in the U.S., but are direct, more refined descendants of the first "soddies" settlers carved out of the plains on their journey westward.
The green roof state-of-the-art is slightly more refined. According to the advocacy group Green Roofs for Healthy Cities, modern green roofs consist of plants, soil, a layer of drainage material to help remove excess water, and a waterproof membrane to keep the roof sealed. Beneath that, a layer of insulation sits atop the roof's structural supports, adding to the green roof's ability to keep things warm in the winter and cool in the summer.
Cincinnati Public Schools is incorporating green roof technology into its Facilities Master Plan, with the help of the Metropolitan Sewer District (since green roofs help control rain runoff, it's not uncommon for sewer and water management agencies to get involved with their installation). According to CPS project manager Robin Brandon, contractor Weston/Green Grid installed green roofs at Taft High School and North Avondale Montessori in less than a week each.
The quick-to-install green roofs are part of a bigger plan to "green" the district's schools, Brandon says.
"All projects in Segment 3 of the CPS Facilities Master Plan will be LEED silver certified," he explains. "The green roofs are a feature we have designed into some projects." Green Roofs for Healthy Cities reports that a green roof can add a "significant improvement" to a building's LEED score, a measure of its environmental friendliness.
Brandon also notes that the North Avondale roof will have an educational benefit. Since it's accessible from the school's science classrooms, he says it will be incorporated into students' learning activities as its plants grow and become more established.
CPS has plans to install a green roof at Clark Montessori, and Rothenberg Preparatory Academy, Oyler, and Quebec Heights are all considering green roof projects, he explains.
CPS' available acreage of roof space, including Taft's 32,000 square feet, makes it the biggest player in Cincinnati's budding green roof scene. However, the designation for largest green roof in Hamilton County will later go to the Museum Center when it's current 7,600-square-foot roof is expanded, according to Steve Terheiden, senior director of facilities and operations for the Center.
Again, the Metropolitan Sewer District played a role in this environmentally friendly project.
"There was a special partnership with the Metropolitan Sewer District (MSD) to fund all of the green of this project," Terheiden says. "MSD understands that in putting a green vegetative roof on top of the roof system, we thereby limit certain about of water runoff during rainy periods and help control storm water run-off."
Despite the help, Terheiden says the project ran into challenges. First off, green roofs aren't the lightest, and the flat roof on Union Terminal's southwest corner was not the sturdiest structure to build on.
"We were limited to 17 pounds per square foot of saturated weight, which is about as light as you can get for a green roof," he says. "Further, the flat roof systems have far exceeded their useful lives and have failed, which resulted in significant deterioration of the building envelope. So we removed the roofing that had been added over the years and the original roofing, taking away weight to make it possible to install a green roof."
The green roof added up to about five months' work and $180,000 of the $500,000 it cost to restore that part of the terminal's roof. But Terheiden says the lessons learned in the project will pay dividends in the future, when the rest of Union Terminal's 100,000 square feet of roof get the green treatment. It's all part of the master plan for restoring the terminal, he says.
And with a green roof on a place like the Museum Center, one has to expect that there's educational value being tapped. The center installed a web cam on the roof, and Terheiden says it - and online information about the roof - have been extremely popular.
"We have had a good response on the green roof," he says. "I think guests are interested and excited in the fact that such a modern technology is being used on a historic landmark. People might not fully understand what the green roof is, so the web cam allows them to see it and watch the continual growth."
Between the educational programming being planned around CPS' green roofs and the very public nature of Union Terminal's first step into this growing technology, one could suspect that Cincinnati's take on grassy rooflines may soon change. What was once considered an eyesore may soon become a sign of environmental awareness, and of a clever application of old technology to improve modern-day living.
Photography by Scott Beseler
Green roof atop Taft High School facing East
Sprinkler on Taft
North Avondale roof
North Avondale facade
Robin Brandon and Taft project manager atop Taft High School