Imagine renovating a 102-storey skyscraper while reusing 96 percent of its original windows. That's basically what happened at the Empire State Building. In 2009, the building's management decided to rebuild the building's 6,514 old windows without replacing them with new ones. According to Rocky Mountain Institute (RMI), the nonprofit organization involved in designing the retrofit, this decision was actually a key component of a much larger renovation process. The entire project is projected to reduce energy consumption by 38 percent in the whole building, saving up to $4.4 million a year once fully implemented, and paying for itself within three years. This initiative also generated 252 jobs in the process.
The windows never left the building
Instead of stripping out all of the building's 6,514 double-hung windows and throwing them away, they disassembled each one on the spot, then reassembled it with a suspended coated film and a gas fill between the panes. According to RMI's own reporting on the retrofit [rmi.org, "Empire State Building Retrofit Surpasses Energy Savings Expectations"], this more than tripled the insulating ability of every single window. Heat loss in winter was reduced, UV rays were blocked, and tenants near the windows no longer felt the cold drafts. Basically, the building's original 1930s window frames got an upgrade instead of a one-way trip to a landfill.
Why fixing beat buying new
Not only did the historic windows have sentimental value; it was also good business sense. According to RMI's breakdown of the retrofit, the window rebuild was just one of eight energy-saving measures carried out across the building, alongside efforts such as insulating old radiators and installing advanced digital controls. More efficient windows combined with improved lighting and office equipment decreased the building's peak cooling load by almost a third. As a result, engineers were able to remodel the existing chiller plant instead of removing it and replacing it with a larger one. That same analysis states this step alone saved more than $17 million in capital expenses that would otherwise have gone toward new cooling equipment. These capital savings contributed significantly to the financing of the entire retrofit program, which made it cost-efficient enough to pay for itself in just three years compared to a decade it would normally take. At the time, the project also prevented about 4,000 metric tons of carbon dioxide emissions, which is equivalent to the amount of CO2 absorbed annually by 750 acres of pine forest.
