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Empire State Building Exhibits Benefits of Energy Efficiency
The Empire State Building Company hopes the completion of a $20 million energy retrofit project will reduce energy use and costs, and make the building a model for similar building retrofits nationwide.

By Jonathan Samples
A $20 million energy retrofit project for the Empire State Building is expected to reduce total energy usage by more than 38%; cut energy costs by $4.4 million annually; and reduce carbon emissions by 105,000 metric tons over 15 years. A $2-million interactive sustainability exhibit is showing visitors how such savings are expected to be achieved.
            In April 2009, a team—comprised of the Clinton Climate Initiative, Rocky Mountain Institute, Johnson Controls Inc. and Jones Lang LaSalle—unveiled a process for analyzing and retrofitting existing structures for environmental sustainability to be tested on the Empire State Building. As part of a $500 million renovation process taking place at the building, the team joined with the Empire State Building Company to complete the specific energy efficient retrofits that, when finished, could be a model for similar projects worldwide.
            Seattle-based design firm Hornall Anderson created a multimedia sustainability exhibit to tell the story of the Empire State Building’s retrofit program and the importance of energy efficiency through a myriad of interactive exhibits. What follows is a description of the three-step approach being taken in the retrofit and how its application is helping to turn the “World’s most famous building” into a model for energy efficiency.
Step 1: The first step in the transformation of the Empire State Building focused on the 6,514 windows located throughout the 102-story building and the insulated barriers around those windows. To begin with, a window refurbishment project was established to address the wasted energy—heat during the winter and cool air during the summer—escaping through the buildings traditional double-paned windows. To avoid replacing the windows completely, the team refurbished each one of the windows in a custom onsite processing center—which saved money, time and eliminated any carbon emissions that would have been created by transporting them offsite.
            The refurbishment process required each window be cleaned to ensure no dust or dirt is sealed inside. Next, a spacer was inserted and a heat-reflective film was placed between the two panes of glass. An insulating mixture of krypton and argon gasses was then pumped into the windows (the exact mixture of the two gasses varied based on window location and amount of sun exposure). The whole process was relatively unobtrusive, as work crews managed to process 50–75 windows per day. More than 96% of the existing window glass was used in the process, which made the windows up to four times more energy efficient and added 25 years to their life.
            In the second part of Step 1, an inexpensive insulating barrier was installed between the 6,514 radiators located beneath each of the windows. The insulation reflects 24% more heat back into the building and prevents cool air from seeping through the masonry, both of which adversely affect the cooling load. To counter this, each radiator was connected to a digital control system to limit steam consumption to only the amount required to reach setpoint temperatures.
Step 2: The first part of Step 2 required retrofits on the buildings four massive chillers. New variable-speed drives and improved controls were installed, allowing them to adjust their output continuously to meet the buildings needs. This resulted in a 5% overall reduction in energy, because the new drives and controls prevented the chillers from running unnecessarily.
            Next, the building’s air-handling units, like the chillers, were upgraded to operate according to the buildings needs. The new units use VAV technology to adjust output levels according to the particular demands in different spaces throughout the building.
            Finally, the installation of a wireless network connecting every air-handler, chiller, radiator, valve and louver, allows the building and its equipment to be constantly monitored and controlled in real-time. 
Step 3: The final step of the Empire State Building energy retrofit project addressed the ways in which the building’s 20,000 daily employees and its 3.5 million annual visitors consume energy. This will be accomplished by addressing the buildings current lighting ability and giving tenants the ability to monitor their own energy consumption.
            First, all tenants are being encouraged to replace less-effective incandescent bulbs with compact fluorescent bulbs, as they use 75% less energy than traditional bulbs and can last nearly 15 times longer. The team also has looked at ways of streamlining the building’s daylight usage. By encouraging the use of task-specific lighting (lighting that does not require an entire office to be lit for certain tasks), opening office layouts to expose interior spaces to natural sunlight, and installing light censors to make certain lights are “turned off” in unoccupied rooms, the building team hopes to reduce the energy used for day-time lighting.
            The installation of a Web-based digital control system also will streamline energy use in the building by giving tenants the ability to monitor the way energy is being used in their spaces. An online dashboard gives them full access to view their energy consumption and helps them analyze the data to find ways to be more efficient.
The entire project is not expected to be completed by December 2013, but much of the retrofit is scheduled to be finished by October of this year. Already, the Empire State Building has been awarded a commercial building Energy Star rating of 90 out of 100. For more information, visit

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