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New York City’s commercial real estate is facing an inflection point. Formalized remote-work policies have sustained a downward spiral for Class B and C office buildings—those with fewer amenities or located in less desirable spots. Average vacancy rates have risen from just under 10 percent in 2020 to approximately 20 percent today. In contrast, demand for newer Class A office space has stabilized and even grown in recent years. That leaves developers with few options. They could unload office buildings at fire-sale rates, invest in capital-intensive office-to-residential conversions, or commit to wholesale renovations of commercial properties into top-tier office space.

The project blends new and old next to Madison Square Park. Photo © Raimund Koch, click to enlarge.

One Madison Avenue, designed by Kohn Pedersen Fox Associates (KPF) for SL Green Realty and Hines, follows the latter course. The existing 14-story structure, completed in 1958 and composed of a nine-story podium with a wedding cake of setbacks above, was an annex for the landmarked Napoleon LeBrun–designed Metropolitan Life Insurance Company Tower (1909) next door (which was converted into a hotel in 2015). SL Green bought the annex in 2005. It was completely occupied by Credit Suisse, which, after the sale, renewed a 15-year lease. But the investment bank restructured following the global financial crisis in 2008 and decided to decamp in 2017, vacating in 2020. That left the developer with an empty 1.1 million-square-foot office building facing Manhattan’s enviable Madison Square Park.

In 2018, a trio of KPF, structural engineer Severud Associates, and contractor AECOM Tishman won the design competition to reenvision the property. The team—who had already worked together at One Vanderbilt (2020) uptown, another SL Green property—proposed several courses of action, ranging from a simple refurbishment to an entirely new tower on-site. But the building’s 90,000-square-foot floor plates, which span a full city block, were an asset worth retaining. “The plan that won the day, from an economic perspective, was to maintain and reimagine the nine podium floors and build a new, modern tower above,” says Robert Schiffer, SL Green executive vice president.

The core was excavated down to bedrock. Photo © Raimund Koch

Construction began in 2020; the addition of an 18-story tower atop the podium required demolishing the existing building core at the center of the block-long floor plate down to bedrock and pouring an entirely new concrete shear core in its place. Each floor within the podium is studded with a tight grid of columns. The design team studied removing every other column across each level, but low floor-to-floor heights of just 10 feet provided insufficient room for transfer-load interventions. Instead, across each floor, nine of the existing columns were strengthened with reinforced concrete, and four more were added to support the vertical load of the tower above. Some, referred to as “jumbo columns,” are 5 square feet.

“One of the initial concepts proposed reinforcing hundreds of columns and beams across the podium,” says Andrew Werner, KPF senior associate principal. “But our discussions with Severud determined that a new building core would solve many of our load issues.” As he explains, it also freed up space for Class A commercial infrastructure: larger elevator banks, and improved lighting, mechanical, and electrical systems.

Existing 4-inch-thick Alabama limestone cladding was cleaned and repaired where possible, and the design team sourced infill stone as needed from the original quarry. The small punched windows of the original facade—inefficient and not up to New York’s energy code—were replaced with a new double-glazed and unitized curtain wall system. At the spandrels, exterior crenellated steel facing was swapped out for painted aluminum placed behind the glazing. To announce the primary entrance, on Madison Avenue, three structural bays were stripped of limestone, to be replaced with a similar curtain wall treatment.

The tower rises at a 124-foot setback from the podium, facing Madison Avenue, with the new building core at its rear, north-facing elevation. The transition from old to new is delineated at the 10th floor by an expansive terrace overlooking Madison Square Park, and, inside, by two levels of double-height spaces wrapped in triple and quadruple-laminated ultra-clear glass sheets of monolithic scale. There, the steel structural system of the addition is made wholly visible in the form of gargantuan, fiberglass-clad steel trusses that transfer the gravity load of the addition to the column grid below. Those structural decisions, positioning the building core to the flank of the tower and transferring the addition’s vertical load through the trusses, allowed for 60-foot, column-free spans from the 12th floor upward. Further contrasting the addition to the stone-clad podium and the Metropolitan Life tower are dark gunmetal fileted frames running vertically every 15 feet and horizontally at every third floor.

The tower setback makes room for a landscaped terrace, and its steel trusses transfer vertical load to the podium. Photo © Raimund Koch

The mechanical systems of the annex and the Metropolitan Life tower are shared, and services had to be maintained through each stage of construction. The design team first had to install a temporary mechanical room on the eighth floor of the podium and cooling towers on the podium roof, ducts and pipes snaking between the two buildings, prior to dismantling the mechanical infrastructure embedded within a portion of the five uppermost annex floors to be demolished.

To complicate the project further, the New York City Landmarks Preservation Commission required that any areas of the listed Metropolitan Life tower exposed by One Madison Avenue’s partial demolition must be covered up later, in kind. Once the new system was in place—cooling towers located at the building’s summit, a mechanical plant on the north side of the 10th floor—the design team conducted a hot cut, rerouting the ducts and pipes within a tight time frame. The bare wall where the systems and the landmarked tower meet was then clad in the same Alabama limestone. “There was an element of open-heart surgery here, managing the mechanical system while deconstructing the building, all while coordinating with a multitude of city agencies,” explains Werner. “It was an unorthodox process, and we had to walk the Department of Buildings through what was essentially continuous deconstruction and reconstruction.”

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Rockwell Group–designed amenity space (1) and restaurant (2). Photos © Adrian Gaut (1), Jason Varney (2)

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Amenities are crucial to Class A commercial development, and One Madison Avenue includes several spaces for them. At the rooftop, Le Jardin sur Madison, a 6,800-square-foot pavilion designed by Rockwell Group, clad in a limestone-like concrete rainscreen, welcomes tenants with a wood-paneled ceiling, lush furnishings, and sinuous steelwork, and a 5,000-square-foot landscaped terrace. La Tête d’Or, a Daniel Boulud steakhouse, also by Rockwell, located at the ground floor’s northeast corner, welcomes the public into the building with a brasserie-inspired design that features marble and walnut flooring, fabric walls, and glass pendants. In the lobby, and below grade, the 7,000-square-foot Commons, designed by Vocon, is a shared tenant space offering both lunchtime catering and meeting spaces.

The renovated lobby includes common spaces. Photo © Kevin Chu + Jessica Paul

One Madison Avenue substantially reached completion in fall 2023, some three months ahead of schedule; with anchor tenants like IBM, Franklin Templeton, and Coinbase, it is over 70 percent leased. New York’s commercial real-estate market still faces substantial headwinds, but the adroit renovation in Madison Square is a success story in a city hungry for one. And it could provide a road map for the effective repositioning of similar properties across the metropolis.

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