Rooftop Revolution: The Rise of Greenroofs in the Big Apple

It is spring and here you are, sipping your piping hot coffee among wildflowers, listening to the trills of warblers and hummingbirds, following the flutter of monarch butterfly wings with your eyes that become more alert as the morning ticks on. All of this in the big city, where the sky phases through shades of tangerine, crimson, and magenta over a sprawling expanse of verdant rooftops.

A city integrated with, instead of divided from, the natural world: This is the vision Inger Yancey, the founder and president of Brooklyn Greenroof, is working to bring to life, along with other green-roof proponents like The Nature Conservancy, Brooklyn Grange, Alive Structures, and New York City Soil and Water Conservation District.

“When you plant a green roof and include some native perennials especially, you’re creating this very special place for the people who live there, but also for the birds and the pollinators,” says Yancey, a LEED-accredited architect who has been creating sustainable architecture for more than 30 years. 

A green roof is a roof covered either completely or partially with plants and soil and an engineered lightweight growing medium over a drainage layer and a waterproofing membrane. Green roofs are often planted with tiny-leaved succulents called sedum and can include native perennial plants, which come back each year to support birds and pollinators.

Green roofs not only provide crucial habitat and support biodiversity in the urban environment. They also represent a holistic solution to some of cities’ most pressing climate concerns, from extreme heat to stormwater runoff and water pollution, says Shino Tanikawa, the executive director of NYC Soil and Water Conservation District. 

Tanikawa also believes that beyond practical benefits for the homeowner like greater energy efficiency and reduced emissions, green infrastructure also reflects a hope: that efforts to address environmental issues lead to something beautiful, a rehabilitation of the bond between humans and nature.

People who install green roofs on their homes can regularly spot hummingbirds, butterflies, and grasshoppers. “It adds to the beauty, liveliness, and wonder of having a green roof,” Yancey says. (Bonus perk: “Rats do not like green roofs at all,” she adds.)

Green Roofs for All

Brooklyn Grange, the company known for operating the largest rooftop soil farm in the world, also works with homeowners and building owners throughout New York to design, install, and maintain green roofs, gardens, and green walls. The team completes about 10 to 20 new installations each year and maintains over 100 residential landscaping projects across the state. 

Michelle Cashen, a native New Yorker who grew up in Queens, says she joined Brooklyn Grange back in 2014 because she wanted to make New York more sustainable. “I found Brooklyn Grange like every good millennial does,” she says. “On Instagram.” 

Now, more than a decade later, she is the director of design, build, and maintenance, helping New Yorkers incorporate green spaces into their homes that serve the city’s ecology. “Every time we build a green roof or a garden, even though we’re building in this very man-made environment, we are introducing elements of nature into people’s homes or into a business,” Cashen says. 

She emphasizes the value of working with clients even if the budget’s tight. For example, Brooklyn Grange recently installed a green roof in Kingston, New York. “The client didn’t have a huge budget, so we ended up using plugs and seeds to plant the green roof rather than coming in with more mature plants,” she says.

“That’s really exciting to me because we’re working with a client to bring a project to life,” she adds, noting that budget doesn’t have to be a limiting factor. “We’re able to work with clients and find a solution that still leads to them having a green space.”

The Step-by-Step Process

Marni Majorelle, founder and owner of Alive Structures, a landscape company that specializes in green roofs, says the first step  of working with a homeowner to design and install a green roof is a structural engineer’s assessment. 

Though many rooftops can handle at least a shallow green roof, it’s the structural engineer’s job to figure out definitively how much weight the roof can hold.

For step two, Majorelle asks clients what they want out of their space. “Do they want a natural space to walk through? Do they want a deck? Does the client want as low-maintenance as possible? Do they want something much more intensive like growing vegetables up there? I try to understand how the person or the family wants to work with the space.”

What’s next? Majorelle says, “The fun stuff, like choosing the plants, designing the layout, what materials we’re going to use.” The green roof’s system and layers change for each project, she says, “but generally we have the root barrier, a drainage board, a filter fabric, anywhere from 4 to 8 inches of soil medium, depending on how much the roof can hold.”

Staying Cool in Extreme Heat

Cities tend to experience higher temperatures than nearby rural areas, especially during the summer, because they have less vegetation and more heat-absorbing surfaces like dark asphalt roads, pavement, and roofs. Plants cool the surrounding environment, but the man-made surfaces prevalent in cities do the opposite. This phenomenon is called the urban heat island effect, and cities all over the world are grappling with it. 

“As we see the impact of climate change with warming temperatures, this challenge will just get worse,” says Mike Treglia, lead scientist for The Nature Conservancy’s New York Cities Program. 

Thaddeus Pawlowski, the director of Columbia University’s Center for Resilient Cities and Landscapes, is an urban designer who’s passionate about integrating resilience and climate change adaptation into cities’ long-term development. As a former employee of the NYC Office of Emergency Management, Pawlowski is well aware that too many people die in their apartments from heat exhaustion because they don’t have air-conditioning or don’t want to turn it on because of steep electricity bills. In fact, more than 500 New Yorkers die prematurely each summer because of hot weather, according to a 2025 report by the NYC Health Department. 

“Reducing the urban heat island effect is a matter of life and death for a lot of urban neighborhoods,” Pawlowski says. “Having more green roofs will make the city cooler.”

Trees and taller plants, for instance, provide shade. And with all plants, the surface of the leaves help reflect sunlight and heat energy back into the atmosphere. That’s because plants tend to be lighter colored than the asphalt common in urban areas.

To cool down, our bodies sweat. Evapotranspiration is a similar process — as plants absorb water from the soil, some of that moisture emerges through “special holes in the leaves” called stomata. “As that water comes out, it’s evaporating,” Treglia explains. “This provides a cooling effect because it takes energy to make that evaporation happen.”

Green roofs also provide additional insulation, helping with year-round energy efficiency. Pawlowski says greenery can be like “a coat” for buildings in the winter and “a sunhat” in the summer. Buildings lose a significant amount of heat through roofs, which last about 15 to 20 years. “So if every time there’s a new roof, if we could make it more insulated with greenery, it would improve the energy efficiency of these buildings,” says Pawlowski.

In his research using aerial imagery from 2016, Treglia found that of the one million-plus buildings in NYC, only 736 had green roofs. Meanwhile, about a fifth of the city’s landscape is covered by buildings. 

In other words, there’s plenty of room to expand green infrastructure on rooftops. Treglia is currently working on an updated report about the distribution of green roofs in NYC with more recent data. Although his research isn’t complete yet, anecdotally, he’s seeing a lot more green roofs than he did a decade ago.

A Holistic, Nature-Based Solution

NYC Soil and Water Conservation District is a government entity with a board of directors appointed by the mayor and the city council that focuses on partnering with community organizations to promote eco-friendly practices. 

According to Tanikawa, by the time she joined in 1998, the leadership was already “interested in nature-based solutions.” 

“They understood that a lot of problems in the water quality in New York City stemmed from the fact that we paved over the surfaces,” she says. “And what we needed to do was essentially rip open some of those pavements to create vegetated places.”

When it rains, that water has to go somewhere. Since much of NYC’s surface has been paved over, city engineers developed a system of underground pipes to drain stormwater from the pavement. At the time, over 100 years ago, the city connected these pipes to the household sewer system. 

“The engineers wanted to make sure that when the pipe gets filled up, the sewage doesn’t back up into apartment buildings,” Tanikawa explains. “So instead, they created what can be thought of as a relief valve where when the pipes get filled up, that mixture of rainwater and sewage gets discharged into our waterways.”

Today, this combined sewer system serves the majority of the city’s surface (about 60%). Meaning, in most of NYC, wastewater goes into sewer pipes that connect with a system of underground drainage carrying water from the street and roof surfaces. 

On a day that’s sunny and dry, that sewage goes to the sewage treatment plant. However, on a rainy day, and especially during an intense storm, the pipes often reach their capacity, and the mixture of rainwater and sewage goes directly into the Hudson River, Jamaica Bay, Newtown Creek, or whatever body of water is nearby. 

“In essence, that is raw untreated sewage being discharged into the water, and that actually happens without a torrential downpour in some neighborhoods,” Tanikawa says. “In some neighborhoods, this kind of discharge can happen with as little as a quarter inch of rain, and that’s really been the big problem in trying to make our waterways safe for swimming and fishing.” 

For Tanikawa, the power of green infrastructure is that it’s a holistic solution. Green roofs address water pollution by soaking up rainfall before it can make it to the sewer, while also providing plenty of other benefits.

That includes better psychological well-being. In fact, there’s robust research pointing to the importance of green spaces for mental health. Studies suggest that access to nature can reduce the stress associated with loneliness, a problem on the rise in cities. While living in urban areas with more green space, people also reported less mental distress, less anxiety and depression, greater well-being, and healthier cortisol profiles, according to research published in the Journal of Epidemiology & Community Health. 

“Green roofs are just phenomenal spaces because you have that open sky, which gives you this beautiful sense of hope to start with, but then you’re surrounded by vegetation that gives you a boost to that hopefulness,” Tanikawa says. 

And it doesn’t have to be a full-on green roof. Adding any vegetation makes a difference. For example, Tanikawa’s top floor neighbor has the rights to the roof. “While it’s not a green roof,” Tanikawa explains, “there are planters up there. She’s growing herbs and whatnot.”

“When I get invited to the rooftop, I feel my blood pressure drop,” Tanikawa says. “Just to be surrounded by plants on the rooftop of the building is an incredible luxury that I want everybody to experience, and it shouldn’t be a luxury. We have so many rooftops in New York City, and every single rooftop should have vegetation.”