Willis Tower Sets Energy Star Mark

The 4.5 million-square-foot Chicago high-rise now holds the distinction of being the largest office building in the U.S. to earn the EPA’s Energy Star certification.

Willis Tower, Chicago
Willis Tower, Chicago

Chicago’s iconic Willis Tower just got a whole lot greener. The 4.5 million-square-foot, 110-story skyscraper recently achieved U.S. Environmental Protection Agency’s ENERGY STAR certification, making the Windy City’s tallest building the largest office building in the country to receive the designation.

“We are continually focused on improving energy efficiency and lowering operating costs, and this recognition, including being the largest office building ever to receive ENERGY STAR, is a testament to our team’s non-stop efforts and innovations.” David Moore, a senior vice president with Equity Office, the owner and manager of Willis Tower, said in a prepared statement.

News of Willis Tower’s certification emerges less than one month after Equity Office announced that it had tapped technology company Entic to facilitate increased operational efficiency and utility savings at the building originally known as the Sears Tower. Energy efficiency was not at the top of developers’ list in 1973, when the doors of the high-rise swung open for the first time, so securing the ENERGY STAR label makes the accomplishment all the more significant. Simply put, ENERGY STAR-certified properties help protect the environment while providing the added benefit of reducing operation cost—or vice versa. On average, such buildings require 35 percent less energy and produce 35 percent fewer greenhouse gas emissions than comparable buildings across the country.


The list of changes employed at Willis Tower to bring the property up to ENERGY STAR standards include the retrofitting of the building’s HVAC, as well as the comprehensive upgrading of the building’s automation system, allowing for greater efficiency in temperature control. To conserve lighting, Equity Office added motion sensors in certain areas and lighting control panels in others and installed high-efficiency LED fixtures and lamps. Additional energy savings will be achieved as a result of the retrofitting of Willis Tower’s cooling towers and the upgrading of half of the property’s chillers.

Willis Tower isn’t just getting an energy efficiency upgrade; the renowned office and retail high-rise is undergoing its first-ever comprehensive renovation. The $500 million project entails a reconfiguration that will yield the addition of 300,000 square feet of new experiential retail and entertainment space at the base of the building, and 150,000 square feet of tenant-exclusive amenity space. And topping it all off will be a 30,000-square-foot outdoor deck and garden space.

The modernization efforts at Willis Tower will reach completion in 2019.

Image courtesy of Equity Office