LPC approves high‑performance simulated double‑hung windows for top floor at 640 Park Avenue

The Landmarks Preservation Commission on Feb. 25 approved replacement of the twelfth‑floor windows at 640 Park Avenue in the Upper East Side Historic District with simulated double‑hung, aluminum‑clad wood windows that are triple‑glazed for improved energy and sound performance.

Architect Matthew Veeder presented the proposal to replace nonoriginal windows at the twelfth/top floor with triple‑glazed, simulated double‑hung units. The new windows feature a fixed upper sash and a tilt/turn lower sash that pivots inward for cleaning; the project team said the full assembly will be set back within the deep window reveals and will be finished in black paint to minimize visual change from street level. The applicant emphasized acoustic benefits for the owner, represented in the hearing by the Swiss ambassador’s residence, and said the proposed windows are custom and robust — roughly 329 pounds per sash — given the large glazing dimensions.

The nut graf: commissioners and staff found the windows appropriate because they closely match historic profiles and will be difficult to perceive at the 12th‑floor elevation; the commission noted the units are eligible for staff‑level approval when proposed for the entire building but required a commission determination because the submission covered only the top floor. Commissioners also cited expected improvements in energy efficiency and sound insulation as persuasive.

Public testimony included support for a broader windows master plan for the full building from Friends of the Upper East Side and the Historic Districts Council; the Victorian Society urged caution about faux double‑hung units as a broader precedent. Commissioners approved the top‑floor replacement unanimously.

Action: motion to approve passed unanimously; staff will monitor details and installation.