Thinking Outside the Box of a Decommissioned Elevator Shaft

In the first quarter of 2023, over 16 percent of offices in New York City were vacant. This led to the mayor reviewing regulations, zoning, and levies to encourage the property market to convert empty offices into apartments. If this empty space was made into housing, he believes, it could provide 20,000 new homes over the next decade.

While not every building is appropriate for conversion technically or financially, the property market is responding and we’re seeing a growing appetite for adaptive reuse. Conversions that have made the headlines include One Wall Street and 180 Water Street with many more planned in and around New York City.

There are significantly more elevators in an office building compared with a residential development. Tetra Tech’s vertical transportation experts look to maximize the potential of every square foot through finding innovative solutions to repurpose elevator shafts.

Converting to residential elevator

The starting point for any conversion is analyzing what’s currently in place, what’s needed in the future, and what can be removed or repurposed. Here are some key considerations when converting to a residential elevator system:

Traffic flow and capacity

Residential and commercial elevator traffic differ. Residential buildings house fewer people and have a lower peak arrival rate. Occupants also tend to accept longer waiting times, meaning fewer elevators are required.

Modernization

Reusing an existing core makes sense, both financially and in terms of sustainability. There are significant construction costs and time savings in reusing an existing core, as a building is able to retain much of the existing elevator steelwork, reducing labor and material costs. This also reduces the amount of embodied carbon produced, leading to more sustainable design.

Smart technology

There will be opportunities to radically improve the user experience through technology for both a new and reused elevator core. This could include touchless smart phone interfaces, access control, and destination dispatch systems.

Emergency preparedness

Codes are a critical consideration in conversions, as they differ depending on a building’s intended use. Old buildings need to be upgraded to meet current requirements. At a minimum, these three code-related elevator requirements need to be considered during a conversion:

• Power Loss: Standby power is required for all elevators
• Medical Emergency: At least one stretcher-compliant elevator is required to serve all floors, assuming the building is more than four floors high
• Firefighter Response: At least two fire service access elevators (FSAE) are required to serve all floors in buildings taller than 120 feet (or one FSAE in New York City)

Many 20^th century buildings used much smaller elevators and lack sufficient space to accommodate a stretcher and FSAE. In these cases, significant shaft modifications may be necessary.

Accessibility

Elevators need to be compliant with accessibility standards as outlined in the Americans with Disabilities Act.

Sustainability

All conversions should have sustainable design in mind and, possibly, sustainability certification requirements. Examples such as high-efficiency lighting, fans with low power consumption ratings, and controls that de-energize the cab when unoccupied and not in use all improve environmental impact and increase appeal to potential tenants.

A building owner, tenant, and facilities manager can also benefit from reduced running costs of regenerative drives and AC gearless machines, as well as remote monitoring systems that facilitate predictive maintenance.

Homes need fewer elevators than offices

Let’s take a 100,000 square-foot, 14-story office that was built in the early 1900s. It has an old-school cellular layout with retail on the ground floor and there are five elevators serving the office floors.

If we convert this to a residential building and add on an additional eight floors, the converted building size increases to 130,000 square feet. For this building, we’d only need three elevators. If all existing elevator shafts are used, this means we can decommission two of the existing shafts and free up 70 square feet on each floor. This adds up to 980 square feet over 14 floors.

The average cost per square foot for a luxury new development in Manhattan is approximately $2,500. The elevator shaft space alone increases the building’s value by over $2 million.