NEW YORK (CNNMoney) — The Empire State Building is on an energy diet.
The hulking building, a symbol of American power and, to some, excess, has cut its energy use by 20%.
And that's just due to changes to the building's exterior. Once retrofits are made to tenant spaces on the inside, the second tallest building in Manhattan will be nearly 40% more efficient.
The retrofits will cost $20 million once they're complete, and are expected to save the owners $4.4 million in annual energy costs.
"After one year, we have proven that investing in energy efficiency gives building owners a dollars-and-cents advantage," said Dave Myers, a president at Johnson Controls, which conducted the retrofit.
The renovations are part of a $500 million rehab plan for the building. The building's owners, Malkin Holdings LLC, filed for an initial public offering back in February which valued the building at $2.5 billion.
The changes to the Empire State include:
–Filling the existing windows with an energy saving gas and adding an additional plastic pane.
–Upgrading the building's cooling system.
–Using computerized "smart" energy management technology that can adjust temperatures floor by floor.
–Provide tenants with detailed energy use in their space.
–Automatically shut off lights in unused areas.
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