Extreme caution! The trials and tribulations of renovating historic buildings in NYC

The challenge of old age

From my perspective as an engineer, artifacts—think antiquated heating systems—are rarely embraced. While my architect colleagues preserve timeless turn of the 20th century facades, plaster ceilings, ornate tiles, and intricate stonework, a building’s life systems (heat, air conditioning, electricity, plumbing, fire, and life-safety) typically come with an expiration date. 

When historic buildings are also registered landmarks, the challenge can rise to a whole new level. That was the case with The Astor, a recent residential condominium retrofit and upgrade.

Built in 1901, The Astor is a classic prewar complex on the Upper West Side; its three distinctive towers occupy an entire city block at 235 W. 75th Street. Working with the developer HFZ Capital Group, BP Architects, and Pembroke & Ives interior designers, this intricate redevelopment included:

• Converting the 200-unit residential complex with studios and 1-bedroom units to 65 luxury 2-, 3-, and 4-bedroom units.
• Incorporating a new 2-story penthouse addition to the north tower.
• Adding a new 1-story penthouse addition to the south and middle towers.
• Renovating the lobby and adding new residential amenities, including fitness centers, child playroom, bike storage, tenant storage, and laundry facilities.

In addition to the usual challenges of renovating an historic structure, The Astor was occupied during much of the design and construction period. The work was completed in phases as rental leases expired and in consideration of the 20-plus rent-stabilized units that were maintained.

Rooms—and sidewalks—with a view

Air conditioning was invented in the early 1900s initially to control humidity in industrial plants. Today, central air conditioning is non-negotiable in the New York City commercial and residential real estate market. Designing a central heating, ventilation, and air conditioning (HVAC) system in a landmarked property—or any older property—presents a host of technical challenges related to aesthetics, site lines, size, noise, weight, and vibration.

The Astor is one of 36,000 landmarked structures in New York City. Any interior or exterior changes to these buildings must be reviewed by the local Landmarks Preservation Committee (LPC), bringing an extra layer of scrutiny and care to the process.

One key concern for LPCs is street-level site lines. The design of a HVAC system must consider the height of the equipment and louver requirements (sizes and locations). This may dictate (and eliminate) certain HVAC system options and equipment locations. These decisions are addressed early on with the client, architect, and structural engineer because the answers will impact design decisions and the construction budget.

For example, the new HVAC system for The Astor is a two-pipe water source heat pump system. Originally, a new cooling tower was proposed for the high-roof of the new penthouse on the North Tower of the building. This placement would shield the equipment from view of condo and penthouse residents. However, the LPC rejected this location because the units would be highly visible from the street. Ultimately, the cooling towers were relocated to the lower roof and toward the back of the building. This balancing of the best interests of building occupants and of the public, particularly concerning views, is fundamental to the LPC’s role.

Preserving historic integrity

When you consider that most engineering systems must extend to every corner of a building, the challenge of renovating while preserving historic integrity is evident. Several years ago, Stantec engineers were involved the design of the Great Northern Food Hall in Grand Central Terminal. Here the LPC and MetroNorth required the design team to retain the historic terrazzo floor tiles and did not permit coring for electric and plumbing utility services.

In response, we designed a raised platform system to elevate the six food stations. This structure houses the electrical conduits and plumbing piping for the kitchen equipment and point-of-sale systems. In addition, we specified an overhead structural truss system to run the electrical conduits for track and spot lighting, and to house the pressurized sanitary waste piping pumped from each food station. The gorgeous, well-trod terrazzo tiles are intact and continue to embody the story of this famous transit nexus.

Make it or break it decisions

The architect, engineers, and contractor team must have a strategy for physically moving a new HVAC system in and through the existing building, while shifting the old system out.

For older buildings, the logistics of moving new equipment from a flatbed truck on a congested street to its final resting place in the building are far from simple. Will it fit in the elevator? Will it fit through the service corridor and the doors leading to the mechanical equipment room? Will the crane be able to maneuver the equipment to the setback in the back of the building? Can we take out windows or a portion of the façade to lift the equipment in place? All these questions must be considered when specifying equipment. These discussions should take place with the manufacturer to see if the equipment can be broken down into several parts. If a construction manager is on board, get them involved with installation logistics. 

We’re currently working on the mechanical, electrical, and plumbing (MEP) design for 222 Broadway on Manhattan’s Lower Eastside. Here, the shuttered Bialystoker Home for Aged is being repositioned into luxury condominiums. The 1931 building is landmarked, but the new design requires a modern failsafe—an emergency generator. Our team, working with the construction manager and structural engineer, determined that removing a portion of the roof to lower the new generator into a 10th floor mechanical room was the best solution. In this case, the generator could not be located directly on the roof because of the landmarked status and its visibility from the street.

Hidden basement treasures

I am always delighted to find objects that reflect the lives of the people who once worked or lived in these memory-laden structures. One of my favorite discoveries occurred at the iconic Puck Building at 295 Lafayette Street in Soho. The team was repositioning the top two floors from commercial office space to ultra-high-end luxury condominiums and adding a two-story 7,500-square-foot penthouse (later put on the market for $60 million). Other renovations included new MEPs infrastructure, including a cooling tower, emergency generator, fire pump, and upgrade of all existing utilities (electric, gas, domestic water, fire water), including a new underground electric transformer vault under the Mulberry Street sidewalk.

In the basement, where the best treasures often reside, we uncovered two industrial flywheels from steam engines that once powered the original printing presses at this 1886 Romanesque Revival building. With the encouragement of the design team, the new retail tenant (REI) incorporated the striking flywheels into their flagship store.

This building also has an existing water tower, common among older NYC buildings, and unique to the NYC market. We no longer needed the gravity powered water tower as the new design featured a pressurized/pumping system for domestic water and sprinkler/standpipe systems. Instead of demolishing the obsolete structure, the LPC elected to keep the abandoned structure in place. We filled this vestige tower with sandbags to keep it structurally sound during high-wind conditions.

Embracing iconic buildings

Other parts of the globe enjoy a rich and fascinating architectural history spanning centuries. By comparison, post-Colonial era cities in the US are quite young. Our oldest cities, like New York, are nevertheless home to iconic structures that are recognizable throughout the world: Grand Central Terminal, the Empire State Building, City Hall, Flatiron Building, New York City Public Library, Plaza Hotel, St. Patrick’s Cathedral, and so many more.

It is rare that a developer can afford to create this type of grandeur in a new building. I feel honored to work on these buildings, and with the LPC, to preserve the past and ensure the building’s legacy lasts for another century and beyond.