635/641 Avenue of the Americas

Case Study for 635/641 Avenue of the Americas


SL Green

LEED Certification Level:

LEED EB: O+M v3 Gold



Total Square Feet:


SIG team members that worked on this project:

Asa Posner - LEED PM

Jenn Mahon - LEED QA/QC

Jeff Stewart - LEED Engineering

Nick Kassanis - Engineering QA/QC

Building Address:

635-641 6th Ave

New York, NY 10011

Year Built:


635/641 Avenue of the Americas

SIG's Role on this building:

  1. LEED Consulting

  2. Engineering


635/641 Avenue of the Americas is conveniently located in the heart of Chelsea between 19th and 20th Streets in New York, NY. Once home to the Simpson Crawford Department Store, the buildings have recently been redeveloped into Class A office buildings featuring a new lobby, elevators, state-of-the-art building systems and a one-of-a-kind penthouse rooftop that includes a bocce court and event space. Completed in 2015, the building is now one of the most desirable office properties in its sub-market. If the architectural detailing was discreetly elegant, other features were among the most innovative in the city. The building’s escalators were the first installed in any building on Sixth Avenue while the plate glass for the ground story windows, far larger than standard size panes, were custom-made. The windows were peopled by another innovation – the mannequin, a new concept that gave viewers the impression of what the featured garments would look like when worn.

SIG provided LEED consulting and engineering services for 635/641 Avenue of the Americas’ LEED v3 EB: O+M effort in 2020. SIG helped the building maximize water efficiency by recommending strategic upgrades, resulting in a 41% water use reduction. SIG’s engineering team also helped to optimize the building automation system, resulting in an ENERGY STAR score increase high enough to allow the property to achieve a 2020 ENERGY STAR label. 635/641 Avenue of the Americas achieved LEED Gold certification in July 2020.