Architects are cutting big holes in the middle of skyscrapers and adding more floors to turn empty NYC offices into apartments

• With remote work here to stay, office buildings are struggling to attract tenants. 
• Some in the real-estate and building industries are leaning into office-to-residential conversions.
• A developer and an architect explain how they transformed NYC financial district office buildings. 

New York is facing twin real-estate crises: a massive amount of empty office space and almost no new housing construction. 

The pandemic-induced shift to remote work caught many in the commercial real-estate industry off guard. But some developers and architects have used the opportunity to lean into a business model they'd been pursuing long before COVID-19: turning empty office buildings into housing. 

They include the real-estate development and investment firm Vanbarton Group and the architecture firm Gensler. They're currently finishing up their transformation of 160 Water Street, a 1970s office tower in lower Manhattan that will become 586 apartments. This comes after Vanbarton worked with the architecture firm CetraRuddy to convert a similar building at 180 Water Street into 574 units back in 2017. 

Their work has drawn support from politicians like Mayor Eric Adams, who has announced plans to grease the wheels of office-to-residential conversions. Most of the estimated 96 million square feet of vacant office space in New York City would be prohibitively expensive, or illegal, to turn into housing. But in some cases, it's feasible. 

The conversions each pose unique challenges. A universal issue is the lack of air and light in the center of these large commercial buildings, and making more windows available for apartments can require extreme makeovers to those looming, dark office towers.

Shifting square footage around

With both Water Street projects, Vanbarton and their partners took especially dramatic measures to turn the modernist skyscrapers into livable spaces. This included cutting holes in the center of the buildings, adding new floors, and replacing all of the windows. 

At 180 Water Street, the architects designed a 30-by-40-foot courtyard in the center of the building to bring light and air into several apartments and mechanical spaces. They also built new floors on top of the building to make up for the lost square footage and added a pool, roof-deck, gym, and other amenities. 

At 160 Water, they cut three central "blind shafts," or voids, that run the height of the building to eliminate space that was too far from windows to be usable but not big enough to be turned into a courtyard. 

To add back that lost square footage, they turned a double-height floor that used to store mechanical systems into two floors, and added new half-floors to the top of the building with penthouses and terraces, growing the structure from 24 to 29 stories. The building will have almost 35,000 square feet of amenities, including a wraparound roof-deck. Several underground floors will be used for a gym, a spa, and a bowling alley — spaces that don't necessarily need natural light. 

"There was essentially dead space at the back of these units," Joey Chilelli, Vanbarton's managing director, told Insider. "And so instead of adding that to the unit and creating these extremely long units, we took that out and then put it elsewhere in the building where it made much more sense." 

Robert Fuller, a principal at Gensler who led the design of 160 Water, said the blind shafts were "probably the biggest planning challenge" in the project. 

"We couldn't just wall it off and leave the floor slab. We had to physically remove the floor slabs so that it became a true shaft," Fuller told Insider.

The team also had to add lateral reinforcements to the building to support the additional floors, also known as an "overbuild."

"The alternate to that would have been to reduce the size of the overbuild, but then you're losing square footage," Fuller said. "Most developers are not looking to lose square footage if they can avoid it. So it's a cost-benefit analysis that the client has to do during design."

They turned the first floor of 160 Water into a large open lobby with a lounge, coffee shop, and mail room after realizing that retail wouldn't have been the best use of space, Fuller said. 

In both buildings, all the windows had to be replaced with ones that can open. Another major intervention involved upgrading all the heating, cooling, ventilation, plumbing, and other mechanical systems to meet current energy-efficiency standards. The upgraded systems will make both buildings considerably more efficient, and Chilelli said that 160 Water will meet New York's 2024 and 2030 energy-efficiency standards. 

All of this comes at a price, though. Rent at 160 Water will range from about $3,500 for a studio apartment up to $7,500 for a two-bedroom. Demand for 180 Water — where apartments are at about the same price point — was strong and the building filled up quickly. Chilelli thinks there are plenty more people who'd like to move to the financial district. 

But he said he'd like to see state lawmakers make a series of legislative changes that would make office-to-residential conversions easier for developers, and more affordable for New Yorkers. 

"If there are tax incentives tied to some of these conversions by providing a certain percentage of an affordable component to it, I think that will also help and I'd like to see that," he said. 

In the meantime, Chilelli said he evaluates new opportunities for office conversions on a weekly basis, and he's excited for the next project.

Fuller said his team is looking at potential opportunities in both the financial district and midtown Manhattan. The conversion projects are challenging but fun from a design perspective, he said. 

"Any good designer embraces that challenge, trying to come up with creative solutions," he said. "At first blush it would be easy to look at a building like 160 and say, 'Oh, it doesn't work. The floor plate is too deep.' But we were able to come up with a solution." 

As New York looks to revitalize its business districts, office conversions can make a difference. 

"It really does breathe new life into these buildings," Chilelli said. "You're creating this buzz and this new life, and you might have 1,000 or more residents and the effects of that on this street, this corner, this neighborhood and the amount of foot traffic as well as other retail activity — it really boosts the area and changes the streetscape."