Making Landmark Windows Energy Efficient

Apartments and condos face many hurdles when updating old buildings, especially those with landmark windows. Project managers and building owners want to keep intact what makes these buildings inherently beautiful—mouldings, fixtures, wavy glass & old-growth wood frames. At the same time, codes must be met, and modern efficiencies save money and bring convenience to tenants.

commercial landmark building with commercial storm windows nyc building

Joseph Casillo faced these issues and more updating his landmark building. Several floors of this apartment building included landmark windows that were over 100 years old. These old windows let in drafts and grime on the best days, winter storms and NYC city noise on the worst days. Tenant comfort was a big concern for Casillo, and because he was converting these units into condos, property value wasn’t far behind. But due to NYC regulation, these old windows could not be replaced.

commercial landmark building with commercial storm windows insert installation

Casillo talked with 3 or 4 different vendors who provide large storm windows, but couldn’t find what was needed. When he spoke with Alma’s Interior Solutions, he finally found what he was looking for. Working with Indow® inserts expert Alma Bernan, Casillo was able to introduce a mullion (bar separating panes of glass) exactly along the window sash line so that none of the landmark window was obscured.

A little about landmark windows and New York. New York, through its Landmarks Preservation Commission, helps maintain a consistent appearance of historic buildings through a series of regulations. It’s a noble cause—how do we build a visual history if we keep tearing it down—but one that comes with a lot of red tape.

commercial landmark building with commercial storm windows insert installation


Watch Indow Inserts Being Installed in Landmark Building


If a building has a landmark window, or 20, construction can be delayed and many extra specifications must be met, including filing a new permit with the city’s Landmarks Preservation Commission. Because Landmarks is primarily concerned with the building’s outward appearance, Indow inserts work perfectly. You’ll enjoy modern benefits of increased energy efficiency and noise abatement without affecting the outside appearance. There’s no construction on site, so no delays, no mess, and minimal disruption to any tenants (installation for one window takes minutes).

commercial landmark building with commercial storm windows nyc building

Casillo says the window inserts have made a real difference in his building:

“Some of the tenants have said they feel a drastic improvement on the drafts and the noise has died down significantly.”

– Joseph Casillo, Senior Project Manager, 25 Broad Street, New York, NY


Just as the tenants are enjoying the relief from city noise and grime, the fact that these spaces are now quiet, warm, and green will help them sell more easily. That plus the easy installation (thanks to Alma’s Interior Solutions) and acceptance by the Landmarks committee with their strict rules, he says the whole thing went pretty seamlessly.

Read about a manager of a historic apartment building who added quiet and energy efficiency through storm windows in Richmond, VA.

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bedroom with window with indow inserts installed for soundproofing in san francisco