Bringing High-Performance Building to Highbridge

The Highbridge neighborhood of the Bronx takes its name from the iconic High Bridge, which was built between 1837 and 1848 to carry water from the Croton Aqueduct into Manhattan. The steep incline from the banks of the Harlem River made the site ideal for not only the aqueduct, but also the Washington Bridge (completed in 1888) and the Alexander Hamilton Bridge (completed in 1963). Though it no longer delivers water to the city, High Bridge is the oldest bridge in New York City still in operation, and it continues to be a pedestrian crossing that connects Highbridge Park in the Bronx to Highbridge Park in Manhattan.

The property adjacent to the Bronx park’s northeast entrance has long been home to the Highbridge Residential Treatment Program, a facility operated by Samaritan Daytop Village since the 1980s where individuals receive treatment for substance use disorders. The program uses a combination of treatment modalities to develop prosocial attitudes and behaviors while also providing education, training and employment services, and housing assistance to clients. Samaritan Daytop Village’s treatment services, transitional and permanent housing, and a range of other services at more than 60 facilities throughout the New York metropolitan area provide short- and long-term assistance to more than 33,000 people per year.

This facility is currently being reimagined as the Highbridge, a multi-use, all electric development that will replace the existing facility with a ground floor community facility, as well as 106 units of transitional housing for families and 316 units of affordable and supportive permanent housing. Designed by Magnusson Architecture and Planning (MAP), the 400,000-ft2 project is pursuing certification from both the Passive House Institute and Enterprise Green Communities. The development is being designed to integrate with the adjacent Highbridge Park and neighborhood through restorative trails and landscaping techniques that create welcoming spaces throughout the property. These features will include prosocial seating arrangements, planters, and permeable walkways for wayfinding. Additionally, the design incorporates three large terrace spaces that will provide a healing garden with play equipment for families staying at the shelter, as well as amenities for residents like an urban farm, composting system, and chicken coop. The roof will also be home to a 115-kW PV system capable of producing up to 490,000 kBtu/yr.

While these amenities may seem out of place in such a high-density part of the Bronx, their inclusion is part of MAP’s larger goal to promote wellness and health among residents in addition to resiliency and sustainability. “The life expectancy in this neighborhood is 2.6 years shorter than the city average,” says Sara Bayer, associate principal and director of sustainability at MAP. “That helped us frame the project around health more in terms of what positive impacts this project should bring.” This focus on health not only influenced the biophilic aspects of the property’s greenspaces, but also the benefits that come via passive construction, which include a steady supply of fresh and filtered air, thermal comfort, and quieter living spaces. These factors can all contribute to reducing stress, improving sleep quality, and making residents feel better mentally and physically.

One other factor that Bayer noted was the team is trying to incorporate healthier alternatives to conventional building materials, including linoleum and hemp. Though the project is still in the design phase and the team is still exploring its options, Bayer said that she is particularly concerned with vinyl flooring like luxury vinyl tile (LVT), which is toxic and made from fossil fuels. Prior to the 2022 Uyghur Forced Labor Protection Act, it was also largely produced in Chinese facilities that utilize forced labor. “We need better alternatives,” she says.

Additionally, Bayer hopes to cut the embodied carbon of other materials used in construction. “We have numerous ways to lower the embodied carbon of concrete,” she says. “We’ve advocated for ground glass pozzolan instead of fly ash or slag, which is a much healthier cementitious material than those other two replacements. It could also be locally sourced from residential glass recycling.”

Though construction will not be complete until 2026, the Highbridge has already received a Buildings of Excellence award and a Blue Ribbon for Design Excellence award during the third round of the New York State Energy Research and Development Authority’s Buildings of Excellence competition. During the award ceremony, Rosalie Genevro of the Architectural League praised the project for its vision.

“Highbridge deeply impressed the jurors with its high ambition and integrated resolution of every aspect of the project, from its relationship to a topographically challenging site, to material selection, to a construction process designed to minimize waste, to the careful consideration of resident and visitor experience of building entries and circulation,” Genevro said.

Designing Highbridge

The same topography that attracted builders of the High Bridge to the site more than 150 years ago will now make construction of the project somewhat challenging, as they are required to build on a very steep slope running between Undercliff Avenue and University Avenue—the former being approximately 80 feet above sea level, the latter being approximately 150 feet above sea level. Despite this difficulty, Bayer notes that the topography will allow the team to tuck the integrated mechanicals and space for parking into the side of the hill, while the portions of the building extending above University Avenue will be home to the shelter and apartment units.

Meanwhile, one of the benefits of building on this site is that the Highbridge will be set back from the street and away from adjacent property lines, making the delivery of building materials easier and less inconvenient for local residents. At present, the team is exploring the possibility of panelized construction, and the extra room will give them an area to perform mockups, which Bayer says they plan on doing to test the sealant between panels should they decide to use panels.

From a distance, the massing of the Highbridge can give the impression that the development is two buildings, but it is actually a U-shape design, with one arm being longer than the other. The shorter arm will house the shelter spaces, while the taller arm will house the affordable and supportive housing and reach 31 stories in height, with 26 of those stories rising above grade level at University Avenue. The building’s ventilation system will be centralized but split between the two arms of the building, with the ductwork for the ERV systems running up and down each arm. The supply and exhaust ports for the shelter will be located on the roof of the shorter arm of the building (which is level with the 8th floor of the taller arm), while the supply and exhaust ports for the apartments will be located on the roof of the taller arm of the building, along with the solar array. Bayer notes that centralizing the ERV system in this way will allow the team to minimize penetrations in the façade.

Some larger mechanical systems will also be located on the double-height spaces that are set back on floors 5-6 and 17-18, as well as on the roofs of the shorter arm and taller arm of the building, and preliminary designs have proposed placing the condensers for the VRF system outside of the Passive House envelope on these floors. Though the design has not been finalized as of yet, the team believes that the stacked vertical distribution system will reduce the length of refrigerant lines in the building.

Though the building is quite slender on account of its shape, the floor plates are efficient and relatively dense. Consequently, overheating has been a concern through the design phase and the team has taken steps to mitigate it. One issue that has come up concerns the amount of glazing on the south-facing side of the arm that contains the apartments. Bayer notes that MAP tends to aim for 30% glazing as a rule of thumb with this kind of building typology, but that the south-facing view from the site includes the High Bridge in the immediate foreground and the entirety of the New York City skyline in the background. It would be almost criminal to not celebrate and democratize it. Consequently, the team has decided to situate the elevator bank at this end of the building and to use floor-to-ceiling glass along the south-facing wall. To avoid overheating, MAP has designed terracotta shading elements that cut down on solar gains while still providing a nearly unobstructed view. The shading elements will also give texture to the façade of the building, which is certain to become a Bronx icon in its own right.

Construction is set to begin in the summer of next year.