Willis Tower receives highest level of green certification

Chicago’s Willis Tower skyscraper has become the largest building in the U.S. to reach the highest level of energy efficiency

CHICAGO -- Chicago’s Willis Tower skyscraper on Thursday became the largest building in the U.S. to reach the highest level of energy efficiency.

Building owner Equity Office, the U.S. office arm of private-equity giant Blackstone Group, announced that the 110-story skyscraper reached the Leadership in Energy and Environmental Design, or LEED, Platinum certification, the Chicago Tribune reported. It is the top designation for energy efficiency and sustainability under the guidelines of LEED, considered the world's most widely used green building rating system.

Willis Tower attained LEED Gold status in 2018. Efficiency was improved via upgrades to heating and cooling systems, hot water generators, lighting, plumbing and an ongoing major overhaul of the elevator systems, Equity Office said. The elevators make more than 46,000 trips daily and serve about 5.8 million people every year. The modernization project aims to make the elevator system more energy efficient and reduce the travel time of passengers.

The building opened as Sears Tower in 1974, and remained the world's tallest skyscraper until 1996 and North America’s tallest until 2014. The Council on Tall Buildings and Urban Habitat ranks the 1,451-foot-tall (442-meter) tower as the second-tallest building in the U.S. and the 15th-tallest building in the world.

Willis Tower is in the late stages of a $500 million expansion. The renovations call for six levels of entertainment, restaurant and retail space that could become an attraction for the building’s thousands of employees and the 1.7 million annual visitors drawn to the observation deck on the 103rd floor.

Once the expansion is completed in 2020's third quarter, the building will have about 4.5 million total square feet (418,064 square-meter) — including 3.5 million square feet (325,161 square-meter) of rentable offices and 300,000 square feet (27,870-square-meter) of retail.