It’s one of the most iconic buildings in New York City if not the world, but I didn’t realize until this week that the Empire State Building in Manhattan is undergoing a complete refit to make it as energy-efficient as a modern construction and the benchmark against which other large and older buildings should be measured. The proud old skyscraper certainly ranks high in both categories being completed in 1931 it celebrates its 80th anniversary next year. Standing at 381 meters (1,250 ft) tall it’s the tallest building outside of Chicago in the US and contains more than 2.5 million square feet of office/hotel/residential space. The retrofit will take over four years to complete and is now 18 months into the process with the goal remaining of completion of the final eighth stage by 2013. Buildings as large as the Empire State can result in an almost incomprehensible reduction in energy use and the plan is for the skyscraper to become a showcase design upon completion which can be transferred to many other older structures.

The estimated energy savings when the task is finished will run at approximately 38%, whereas improvements to post 1945 constructions typically sees savings of between 10 to 20%. The costs associated with the retrofit are estimated to run at over $13 million however building owners estimate that the improvements will have paid for themselves within five years of completion. As you would imagine with a structure this large the project itself is gigantic in scope and will involve numerous changes to the Art Deco era colossus. Window replacement alone will provide more than 10% of the overall energy savings and experts say that improved glass can shave up to 33% off of the peak cooling costs during the summer months. In all more than 6,500 dual pane, double hung windows are being manufactured on site which constitute more than 26,000 individual panes of glass. In one of the most aesthetic and green campaigns in history, the original design of the windows will not be changed and the visual impact is often completely unnoticed even by those who work in the building. The window replacement has been taking place overnight with workers typically returning the next day without being aware of the giant retrofit.

When the project eventually ends the Empire State building will receive an Energy Star score of 90, signifying that it ranks within the top 10% of most efficient buildings in the US. Other renovations beyond the windows include replacing constant volume air handlers with variable units, retrofitting the chiller plant to reduce cooling loads, improvements of daylighting and energy-efficient lighting systems plus upgrades and modifications to air damper and radiator systems throughout the building. In less than three years time the Empire State will be the largest eco-friendly retrofit ever completed and a model that many hope will be followed not just in New York but in other cities with numerous large and older buildings. The New York example provides great impetus to make such changes, as the cities buildings of more than 50,000 ft.² consume more than 45% of the energy needed for buildings in the entire Big Apple. If the Empire State Building can become green then why not all older structures? Better still retrofitting existing buildings toward longer and more efficient lives also reduces the need for new building construction and material use.