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Photo Essay

Green roofs promote urban sustainability in New York City

They also provide learning experiences, like growing vegetables and studying plants
  • Elementary students from P.S. 41 in New York City Public Schools record observations on the green roof during class. The roof was the first official NYC Greenroof Environmental Literacy Laboratory installed in the city. (Photo: Vicki Sando)
  • The P.S. 442 green roof requires little maintenance after the first year of planting. (Photo: ©2015 Ari Burling Photography)
  • Students from P.S. 442 in Brooklyn grow grapes on the roof along with flowers and other plants.
  • A bee pollinates a flower on the green roof at P.S. 442, also in New York City Public Schools.

Learning to grow vegetables and flowers. Digging in the dirt. Understanding how seasons affect plants. Such learning experiences for students come with a green school roof.

Promoting green school roofs is part of New York City’s larger mission to combat air pollution, conserve energy and reduce the amount of stormwater flowing into sewers and waterways.

Green roofs also reduce the need for air conditioning, thus lessening the “urban heat island” effect—a phenomenon in which concentrated human activity and energy use make metropolitan areas hotter.

Two types of green roofs exist, both of which capture stormwater and give off less heat, says Eric Dalski, founder and partner of Highview Creations, a firm that designed a green roof for Brooklyn’s P.S. 442.

A basic or “extensive” green roof has shallow soil and is easy to maintain. After the first year, the plants are established and require little maintenance and no irrigation.

An “intensive” roof requires deeper soil and an irrigation system, but can accommodate diverse plants and offers greater educational opportunities.

The green roof at P.S. 41 in Manhattan was the first official NYC Greenroof Environmental Literacy Laboratory installed by the NYC School Construction Authority. The school augments STEM instruction with lessons in this outdoor learning space.

The pre-K through 5 school began planning in 2006 for what would become a $2 million, 15,000-square-foot roof project that requires little tending, and is funded in part by grants. The school created a modular extensive green roof system using sedum plants, which are low-maintenance, tolerate dry soil and attract insects.

The school has seen its total greenhouse gas emissions decrease by 23 percent between June 2008 and March 2015, while its Energy Star score increased by 15 percent to a score of 93 out 100, says GELL Founder Vicki Sando, a P.S. 41 STEM teacher and a driving force behind the school’s green roof project.

P.S. 41 has also partnered with two other New York City schools—the Bronx Design and Construction Academy and Brooklyn’s P.S. 442—to produce a guide book that includes examples of green roofs, rooftop gardens, greenhouses, solar equipment and lesson plans.

P.S. 442 focused on agricultural production, native plant life and ecology and horticulture education for its 2,500-square-foot roof project, which was installed in 2010 with help from donated materials and an award from the Lowe’s hardware chain.

A green roof’s “membrane”—the part of the system that prevents leaks—can last from 20 to 50 years, depending on how well a green roof is installed and maintained, says Dalski.