Bye-bye Tar Beach, Hello Green Roof

Growing up in Brooklyn, if you couldn’t make it to the real beach on a hot summer day, all you had to do was go up to Tar Beach. Did you go to Tar Beach?

“It was really hot up there,” my mom told me on a recent visit, as she told me about how she and her friends would spend hours up on the roof using sun-reflectors even to maximize their tans. Ahh, the good old days!

Tar roofs, though hot and contributors to global warming, made great song material, though, you must admit.

The Drifters sang about the sun burning the tar up on the roof in “Under the Boardwalk” and how to forget all your cares “Up on the Roof.” Elton John sat up on his roof and kicked off some moss in “Your Song.”

Perhaps Elton should have cooled his boots for a moment and left the moss alone. Growing plants on roofs — from vegetable gardening to sophisticated sod membranes that soak up urban water runoff and cool the air — are becoming a required building material in cities like Toronto and Chicago. 

I know that tar roofs are not exclusive to Brooklyn, no matter how Brooklyn-centric my point of reference may be. In fact, cities  like Chicago, where new laws are in place requiring new buildings to have green roofing materials, the temperature on a tar roof can be 78 degrees hotter than that on a green roof.

Walk across any asphalt parking lot on a summer day and then walk across a green lawn. You don’t have to be a scientist writing a big fat feasibility study to understand how black top paved surfaces and roofs heat the earth and green areas have the potential to cool it.

In Rochester, NY, The Harley School is employing this technology as one long-term science project and can boast that they are the area’s first school to have a green roof. This sustainable technology will not only act as a natural insulator, keeping the school warmer in winter and cooler in summer, but it will teach its high school students about how buildings affect the environment.

The tar roofs of the past, according to environmentalists, are the bane of city living because they create urban heat islands and contribute vastly to water runoff.  Rather than being just a green trend, cities such as Chicago and Toronto require roofs of new buildings to include cooling, greenhouse-gas absorbing plants.

The Harley School on Oct. 18 installed two 10 x 10 ft. plots of hearty winter grass on the roof of their building on 1981 Clover St. The school spent $2,000 for materials and also received an in-kind installation and materials donation from Zaretsky & Associates landscapers in Western New York.  In order to grow a section of green roofing, school engineers had to assess if the school’s roof could withstand the additional weight of a weatherproof membrane barrier, two inches of topsoil, the weight of the growing plants, and the water they will retain.  The grassy roof serves as a natural insulator and will keep the building cooler in the summer and warmer in the winter.  School officials expect to reap the benefits of these initial costs within 3-10 years.  

Peter Hentschke, a science teacher who will be working with Harley’s upper classmen on researching the impact of the green roof, said the project provides students with hands-on learning. The students will develop mathematical methods and equations to determine how much energy their school saves by comparing temperatures of the school’s different roofing materials. They will also calculate how water runoff is affected by the green roof.

 “Rooftop plants catch rainwater and runoff that would have ultimately run into the sewer and overburden water treatment centers. The students are tracking current rainwater runoff with water gauges and will track this throughout the school year,” he said.  

Chris Hartman, Harley’s social and environmental sustainability coordinator said the students are “all fired up” about learning about the green roof because it has real-world implications.  

“The Harley students are really in the driver’s seat of this project. They know that it is cool to have a green roof, but the challenge will be to come up with the methodology to show how green roofs have an impact in the world around them,” said Hartman. He added that students hope to share the data from the green roof with their classmates, and perhaps local colleges such as the University of Rochester and Rochester Institute of Technology.

If we all started growing green things on our roofs, perhaps by the time these kids graduate college, our cities would from above look less like Tar Beach and more like the ancient hanging gardens of Babylonia. I wonder what songs they will inspire by then.