We were commissioned to design custom new insulating aluminum and glass windows to replace energy inefficient steel windows installed when the building was built in 1929. Our task also included integration of new window air conditioner in standard sized openings. The range of cooling capacity was determined based on the room volume to be cooled, from a small bedroom to a larger open living space. We developed details for the new window configurations to allow for operable casement units meshed with fixed lights, similar to the original window design. Our concept was to design energy efficient windows as if the building was a landmark, which it is not. However, our concept for the new windows not only addressed design issues for the apartment type but also the impact the proposed window air conditioning would have on the principal building façade. As soon as the first windows were installed, residents commented on how quiet their living spaces were in comparison to the original steel windows. This project was well received by the residents of 211 East 35th Street.