When The Durst Organization left its longtime headquarters at One Bryant Park in Midtown Manhattan last year, it had to tear the 85K SF office space down to the studs. That meant creating tons and tons of waste.
Sydney Mainster, a vice president with the prominent New York family real estate firm, was in talks with a contractor Durst hired to recycle its drywall when she was asked a question that might have kicked off the next seismic innovation in construction sustainability: What else do you want to recycle?
Mainster stopped in her tracks. What about the 22 tons of interior glass that was headed straight for the landfill?
“I have a crazy idea,” she remembers thinking. “What if we never put a piece of glass in a landfill in New York City ever again?”
Bisnow/Ciara Long
Sydney Mainster, The Durst Organization’s vice president of sustainability and design management, has pioneered the recycling of architectural glass in New York.
Every time a building is demolished or converted, every time an office is renovated or built out for an incoming tenant, landlords have to dispose of windows. Just 6% of architectural glass nationwide is recycled, according to a Deloitte estimate from 2017. The rest ends up in landfills.
But that’s starting to change as some of NYC’s biggest owners and developers adopt nascent glass recycling technology that could usher in a whole new era for building sustainability.
Considering 10 million tons of building windows are created every year — equivalent to the weight of the Titanic 19 times over — allowing for more of that output to come from recycled glass could reduce the carbon footprint of the real estate industry, responsible for 40% of the world’s emissions.
“This hasn’t been something that has been historically front of mind as an easy-to-recycle material,” Turner Construction Waste and Circularity Program Manager Nelson Russom said. “What Sydney is doing, what Durst is leading and the momentum that is building in NYC, means this is hopefully going to become the more typical thing that happens.”
‘I Can Recycle Your Glass’
Shortly after Mainster asked Durst’s contractor at One Bryant Park, Saint-Gobain, about glass recycling, she was contacted by a family firm called Infinite Recycled Technologies.
The Albert Lea, Minnesota-based company started looking at recycling architectural glass six years ago when it was recycling metal for a local glass company.
“Literally, serendipitously, at some point an email landed where there was a guy out of Minnesota who was like, ‘I can recycle your glass,’” Mainster said in a recent interview at Durst’s new HQ.
Courtesy of The Durst Organization/Guillaume Gaudet and The Durst Organization
The exterior of the The Durst Organization’s One Bryant Park and the interior after demo crews had removed the glass from a meeting room.
Building windows are usually laminated, glazed or coated in thin layers of metal to reflect the sun’s heat, all of which are hard to separate from the glass itself. They are also stuck in place with sealants that add varying degrees of difficulty to separating the glass from its metal frames.
Most glass recycling companies that deal with consumer products, like old Mason jars or beer bottles, don’t take architectural glass. Any contamination going into the furnace at a recycling plant could cost hundreds of thousands of dollars.
Realizing that no company existed to recycle architectural glass, Infinite Recycled Technologies spent a year developing a prototype machine that could delaminate glass and debuted its new business line in 2020.
Because of the challenges, the process to recycle architectural glass involves a lot of different parties and stakeholders.
Owners like Durst contract a demolition company via a general contractor. The demolition company separates the glass from other recyclable materials and smashes it into tiny fragments known as cullet. For exterior windows, the separation process also involves removing film, coating or glazing.
Haulers then take the cullet to a manufacturer that has purchased the glass waste. The manufacturer melts it down.
Manufacturers can use that material to make fiberglass insulation, drywall, carpet tile and ceiling tile products that go back into new buildings or fit-outs. Sometimes, it’s downcycled into glass bottles or crushed into road filler. Glass-to-glass recycling is possible but is only at its very earliest stages of development in the U.S.
Infinite recycled 250,000 tons of glass from 2020 through 2024. In 2025 alone, it has recycled nearly 90,000 tons — the equivalent of roughly 360 Boeing 747s. The company estimates it has twice the immediate available capacity it is currently using, said Patrick Elmore, the recycler’s president of business development, indicating that adoption is now behind the technology.
Sandra Goldmark, an associate dean at Columbia Climate School and director of sustainability and climate action at Barnard College, specializes in the study of recycling building materials and creating a circular economy. She hadn’t heard of being able to recycle glass used in buildings until Bisnow called her.
But after hearing that Durst and some other major CRE players are piloting window recycling, she said it has significant potential to cut down on embodied carbon — the greenhouse gas emissions created during a product’s life cycle from production to landfill.
“As buildings have gotten operationally more efficient, the next important lever to pull as we think about cities is how we build them, the actual materials,” she said. “This is exactly what needs to happen. We need to coordinate across sectors, across organizations to make sure that we develop the markets for these materials, the systems to get them where they need to be.”
Why Isn’t It More Common?
Demand for architectural glass recycling hasn’t emerged at scale simply because most people in the industry don’t know it is possible.
Bisnow/Ciara Long
Skyscrapers, like those seen from South Street Seaport in Lower Manhattan, are often covered in glass that hasn’t been recyclable — until recently.
Mainster launched a 75-member working group a year and a half ago that includes other owners and developers, construction and demolition firms, haulers, recyclers and architects. The group meets every six weeks, often with about 40 parties present.
Other companies in the commercial real estate sector are coming on board. Consigli Construction, Turner Construction and specialized reglazing contractor Skyline Windows have all worked on projects that have involved glass recycling.
Gensler, the world’s largest architecture firm, recently completed its first interior glass recycling project with glass from conference rooms at its own offices. The point was to get an understanding of how the process works and create documentation so that architects can present it as an option going forward, said Carey Gallagher, the firm’s sustainability specialist.
GFP Real Estate, which counts the iconic Flatiron Building among its 14M SF portfolio, recycled 48 tons of glass — roughly 2,000 windows — at 222 Broadway, a 31-story office building in Manhattan’s Financial District that the firm is converting to a 798-unit apartment building.
“We are always working hard to recycle as much material as possible on our projects,” GFP co-CEO and principal Brian Steinwurtzel said in an email. “One of the major benefits of converting office buildings to residential buildings (rather than demolish and build new) is the amount of the building that is saved thereby reducing landfill and CO2.”
Infinite is fielding calls from owners, contractors and architects with inquiries about the process on a daily basis. But they are still just a drop in the bucket compared to the thousands of companies that make up the commercial real estate industry.
“It takes a village to do this,” said Stanley Yee, vice president for sustainability and technical initiatives at Infinite. “It takes all the stakeholders to really get on board.”
The extra time it takes a demolition crew to separate glass is one obstacle, Mainster said. They already separate metals like steel and aluminum, because those can be easily sold to recyclers for a profit. Separating glass would add another day or two to a demolition crew’s timeline without the same payoff.
Anything that comes out of a building during demolition gets put into a dumpster that is taken away by haulers, either to landfill or to a recycler. But recycling glass means adding a separate dumpster to the site — which is especially hard in dense urban environments where sidewalk space is tight.
“When we’re doing our upstate New York jobs or our Massachusetts jobs, it’s a lot easier for us to just have three, four bins on sites,” Consigli Construction Sustainability Manager Liz Allen said. “But these are 30-yarders. They’re massive. So to put two 30-yarders on a job in Manhattan is a little tricky.”
There is a way to make an economic argument for the process, Skyline Windows architectural sales representative Stephen Azierski said. Products containing recycled glass are cheaper than those with new glass, because it’s cheaper to recycle glass than to make it from scratch.
Furnaces that make new glass have to be kept at between 2,732 and 2,912 degrees Fahrenheit for 20 years — hotter than molten lava — whereas furnaces that recycle glass can run 30% cooler.
But at present, the cost savings that a developer might be able to make from using recycled materials instead of new materials isn’t being passed on, Azierski said. If that doesn’t happen, it is going to be hard to convince the chain of companies involved in development, demolition and garbage haulage to buy in.
“Pennies mean something to developers when they’re deconstructing a building,” Saint-Gobain North America Vice President for ESG Dennis Wilson said. “The cheapest way to do this is for everything to come out of the building and for it to go into a dumpster.”