The tallest Passive House-engineered building in the world revealed in the Alloy Block of Downtown Brooklyn

Alloy Development has unveiled new renderings for One Third Avenue, a 63-story tower that will rise as part of the second phase of the Alloy Block in Downtown Brooklyn. Standing at 725 feet, it is set to become the tallest Passive House-engineered building in the world, introducing a mix of market-rate and affordable residences, office space, and retail.

Image: One Third Avenue, Alloy Development

The Alloy Block is a transformative mixed-use development in Downtown Brooklyn, designed to set a new standard for sustainable urban living. Spearheaded by Alloy Development, the project spans an entire city block and integrates residential, office, retail, and educational spaces within a highly energy-efficient framework.

The first phase introduced 505 State Street, a 44-story all-electric residential tower, alongside two Passive House-engineered public schools—the first of their kind in New York City. The second phase, featuring One Third Avenue, will add the 63-story Passive House skyscraper, making it the tallest energy-efficient building of its kind in the world. Blending contemporary architecture with historic preservation, the Alloy Block repurposes 19th-century structures along State and Schermerhorn Streets while enhancing the streetscape with retail and public spaces, including the future Temple Square Plaza.

Image: One Third Avenue, Alloy Development

Once completed, the district will comprise over 1,000 residences, including permanently affordable units, 60,000 square feet of Class A office space, 50,000 square feet of retail, and state-of-the-art educational facilities.

The development integrates new construction with historic preservation. Two 19th-century buildings on State Street and Schermerhorn Street will be repurposed, housing retail and community spaces.

Image: One Third Avenue, Alloy Development

The residential lobby will be located within the preserved State Street building, while a separate commercial entrance will open onto Schermerhorn Street, connecting to the planned Temple Square Plaza.

Image: One Third Avenue, Alloy Development

One Third Avenue’s design responds to the surrounding streetscape. Its podium will align with neighboring buildings along Third Avenue, requiring partial demolition of existing structures. At approximately 100 feet above ground, six floors of office space will be incorporated, each spanning 11,300 square feet.

Image: One Third Avenue, Alloy Development

Above, the residential portion will occupy floors 11 through 60, with 538 apartments, including 152 designated as affordable housing. As part of the broader Alloy Block redevelopment, this phase contributes to a larger vision for sustainable urban living.

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